Chemistry Topics

3-Oxapentane
Another name for Diethyl Ether.
6.022e23mol-1
Avogadro′s number
8.314 JK-1mol-1
Molar gas constant.
Abegg′s Rule
This states that the difference between the maximum positive and negative valence of an element is frequently eight.
Abel Flashpoint Apparatus
A petroleum-testing apparatus for determining the flash point.
Abietic Acid

C20H30O2

A resin acid that is the primary irritant in pine wood and pine resin. It is a glassy or partly crystalline yellowish solid. It belongs to the diterpene group of organic compounds. It is used in lacquers, varnishes, and soaps, and for the analysis of resins and the preparation of metal resinates.

Abietin
Abietin is a resin obtained from Strasburg turpentine or Canada balsam. It is without taste or smell, is insoluble in water, but soluble in alcohol, in strong acetic acid, and in ether.

Abietinic Acid
Another name for Abietic Acid.
Abram′s Law
A rule that the ratio of water to cement for chemical action to impart strength to concrete is 0.85:1.
ABS
Common abbreviation for Acrylonitrile Butadiene Styrene.
Absolute Vacuum
A volume which contains no matter.
Absorbed Dose
The amount of a chemical that enters the body of an exposed organism.
Absorbent
A material which, due to an affinity for certain substances, extracts one or more such substances from a liquid or gaseous medium with which it contacts.
Absorption Band
A dark band in the absorption spectrum of a substance, corresponding to a range of wavelengths for which the substance absorbs more strongly than at adjacent wavelengths.
Absorption Spectroscopy
A technique for determining the concentration and structure of a substance by measuring the amount of electromagnetic radiation the sample absorbs at various wavelengths.
Absorption Spectrum
The collection of wavelengths missing from a continuous distribution of wavelengths.
Absorptivity
The absorbance of a solution per unit of path length and per unit concentration.
Abundance Ratio
The ratio of the number of atoms of an isotope to the number of atoms of another isotope of the same element in a sample.
Ac
Actinium is a radioactive element.
Accelerating Rate Calorimetry
An important method for studying the thermal behaviour of materials.
Accelerator
A machine used to accelerate particles to high speeds.
Acceptor
An atom which is likely to take on one or more electrons when placed in a crystal.
Acenaphthene
Found in petroleum residues.
Acenaphthoquinone

C12H6O2

A polycyclic aromatic hydrocarbon derived from naphthalene that is insoluble in water, but soluble in alcohol. It is used as an intermediate for the manufacturing of dyes, pharmaceuticals and pesticides.

Acenaphthylene
A polycyclic aromatic hydrocarbon.
Acepromazine

C19H22N2OS

More commonly known as ACP it is a phenothiazine derivative antipsychotic drug.

Acetaldehyde
Formed by the oxidation of ethanol this is a colourless fruity smelling liquid that with further oxidation forms acetic acid.
Acetamide
Colourless crystalline used industrially as a solvent.
Acetaminophen

C8H9NO2

More commonly known as Paracetamol, a widely used over-the-counter analgesic.

Acetanilide
Also known as Antifebrin this is a white crystalline solid.
Acetate
An ion formed by removing the acidic hydrogen of acetic acid.
Acetic acid
The acid contained in vinegar.
Acetic Anhydride
The anhydride of acetic acid, used in the manufacture of plastics.
Acetoguanamine

C4H7N5

Used as a raw material for guanamine resins. It is used as a modifier and flexibilizer of formaldehyde resins and as a intermediate for pharmaceuticals.

Acetone
Also known as Dimethyl Ketone, often used as a solvent.
Acetonitrile
Also known as Methyl Cyanide, a colourless poisonous liquid, used as a solvent and in organic synthesis.
Acetophenone
Colourless sweet smelling liquid, also known as Acetylbenzene and Phenyl Methyl Ketone.
Acetyl Chloride
Also known as Ethanoyl Chloride it is a colourless pungent liquid.
Acetylbenzene
Alternative name for Acetophenone.
Acetylene
Also known as Ethyne it is made by the action of water on calcium carbide.
Acetyl-Salicyclic Acid

CH3COOC6H4COOH

Commonly known as Aspirin, a white solid. Used in medicine as an antipyretic and analgesic.

Acheson Process
The Acheson process is an industrial process for the manufacture of graphite by heating coke mixed with clay.
Aciclovir

C8H11N5O3

One of the most commonly-used antiviral drugs, it is primarily used for the treatment of herpes simplex virus infections.

Acid
Compound that gives off H+ ions in solution.
Acid Air
Alternative name for Hydrogen Chloride.
Acid Anhydride
Nonmetallic oxides or organic compounds that react with water to form acids.
Acid Dissociation Constant
The equilibrium constant for the dissociation of an acid into a hydrogen ion and an anion.
Acid Error
A systematic error that occurs when glass pH electrodes are used in strongly acidic solutions.
Acid Gas Scrubbing System
A wet scrubbing system capable of achieving high acid gas removal efficiency by introducing water, caustic, or hydrated lime into the gas stream.
Acid Halide
Compounds containing a carbonyl group bound to a halogen atom.
Acid Number
The quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize the acidic constituents in 1 g of sample.
Acid of Vinegar
Another name for Acetic Acid.
Acid Rain
Rain that is weakly acidic due to pollution.
Acid Sludge
The residue left after treating petroleum oil with sulphuric acid for the removal of impurities.
Acid Treating
A refining process in which unfinished petroleum products, such as gasoline, kerosene, and lubricating oil stocks, are contacted with sulphuric acid to improve their colour, odour, and other properties.
Acid-Base Indicator
A weak acid that has acid and base forms with sharply different colours.
Acidic
Describes a solution with a high concentration of H+ ions.
Acidic Solution
A solution in which the hydrogen ion activity is higher than that of the hydroxide ion, when the solvent is water.
Acidulant
A substance added to food or beverages to lower pH and to impart a tart, acid taste.
Acoustic Agglomeration
High intensity sound waves are used in a fluid to group suspended particles into larger aggregates.
Acraldehyde
Alternative name for Acrolein.
Acridine

C13H9N

A colourless solid, was first isolated from coal tar. It is a raw material used for the production of dyes and some valuable drugs.

Acroleic Acid
Alternative name for Acrylic Acid.
Acrolein

C3H4O

the simplest unsaturated aldehyde. It has a piercing, disagreeable, acrid smell similar to that of burning fat.

Acrylamide

C3H5NO

A white odourless crystalline solid, soluble in water, ethanol, ether and chloroform.

Acrylic
Synthetic resin made from acrylic acid or a derivative thereof; acrylics possess the property of transparency and offer flame resistance.
Acrylic Acid

C3H4O2

The simplest unsaturated carboxylic acid with a vinyl group at the a-carbon position and a carboxylic acid terminus.

Acrylic Aldehyde
Alternative name for Acrolein.
Acrylonitrile

C3H3N

Pungent-smelling colourless liquid that often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics.

Acrylonitrile Butadiene Styrene
A common thermoplastic used to make light, rigid, moulded products such as piping.

Acryloyl Chloride

C3H3ClO

A clear, light yellow, flammable liquid with an acrid smell.

Actinic
Pertaining to electromagnetic radiation capable of initiating photochemical reactions.
Actinide
Elements 89-102 are called actinides.
Actinium
A radioactive element.
Activated Carbon
Also known as Activated Charcoal.
Activated Charcoal
A porous form of carbon that acts as a powerful adsorbent.
Activated Complex
State of highest energy during a reaction.
Activation Energy
For the forward reaction is the energy required to go from reactants to the transition state.
Activation Overpotential
The overpotential which results from the restrictions imposed by the kinetics of charge transfer at an electrode.
Active Material
The material in the electrodes that takes part in the electrochemical reactions which store-deliver the electrical energy.
Active Metal
A metal that is easily oxidized in air.
Active Site
A pocket or crevice on an enzyme molecule that fits reactant molecules like a hand in a glove.
Active Transport
Energy-requiring transport of a solute across a membrane in the direction of increasing concentration.
Activity
The rate at which a collection of radioactive nuclei decay.
Activity Coefficient
The ratio of activity to concentration.
Adakane 12
Another name for Dodecane.
Adamantane

C10H16

A colourless, crystalline compound with a camphor-like odour. It is a cycloalkane and also the simplest diamondoid.

Addition Compound
Compound contains two or more simpler compounds that can be packed in a definite ratio into a crystal.
Addition Reaction
A chemical reaction in which two atoms or groups of atoms are added across a double bond.
Additive
A material added to another, usually in small amounts, to impart or enhance desirable properties or to suppress undesirable properties.
Adenosine Diphosphate

C10H16N5O13P3

An important organic compound in metabolism and is essential to the flow of energy in living cells.

Adenosine Triphosphate

C10H15N5O10P2

A nucleoside triphosphate used in cells as a coenzyme.

Adhesive Tape
A tape with a sticky substance on one side.
Adiabat
A line on an indicator diagram that represents an adiabatic process.
Adiabatic Ionization Energy
The lowest energy required to remove an electron from an atom, ion, or molecule in the gas phase.
Adipic Acid
White crystalline solid used in the manufacture of nylon.
Adipoyl Chloride

C6H8Cl2O2

A hazardous chemical that evolves HCl when reacted with water. Can be reacted with hexamethylene diamine to form nylon.

Adipoyl Dichloride
Alternative name for Adipoyl Chloride.
Adsorb
To collect molecules of a substance on a surface.
Adsorbate
A material that is adsorbed.
Adsorbent
A substance that collects molecules of another substance on its surface.
Adsorbtion Chromatography
A technique for separating or analyzing mixtures that contain at least one component that is preferentially adsorbed by the stationary phase as it moves over it.
Adsorbtion Indicator
A substance that indicates an excess of a reactant in a precipitation reaction.
Adulterants
Chemical impurities or substances that by law do not belong in a food, or pesticide.
Aeolotropy
Aeolotropy is the antithesis of isotropy.
Aeration
Preparation of a saturated solution of air gases by either spraying the solution in air or by bubbling air through it.
Aeration Tank
A chamber used to inject air into water.
Aerial Acid
An old name for carbon dioxide.
Aero Metal
A metal used in casting made from aluminium, zinc and copper.
Aerobic
Requiring or occurring in the presence of oxygen.
Aerosol
A colloid in which solid particles or liquid droplets are suspended in a gas.
Affinity
Chemical attraction.
Ag
Silver is a pure white metallic element. The best electrical conductor and used in photographic emulsions.
Ag2S
Chemical formula for Silver Sulphide.
Agar
A gel made from seaweed used to make salt bridges.
Agent Orange
A toxic herbicide and defoliant used in the Vietnam conflict, containing 2,4,5-trichlorophen-oxyacetic acid and 2-4 dichlorophenoxyacetic acid with trace amounts of dioxin.
AgI
Chemical formula for Silver Iodide.
Agitator
A device used to cause motion in confined fluids.
AgNO3
Silver Nitrate.
Air
The main constituents of air are Nitrogen, Oxygen, Argon, Carbon Dioxide, Neon, Helium along with a number of other trace gases.
Air of Vitriol
An old name for Sulphur Dioxide.
Air Set Cement
A cement that sets through loss of water.
Al
Aluminium is the basis for a number of alloys.
Al2Br6
Chemical formula for Aluminium Bromide.
Al2I6
Chemical formula for Aluminium Iodide.
Al2O3
Chemical formula for aluminium oxide.
Al2O32H2O
Chemical formula for Bauxite.
Al2S3
Chemical formula for Aluminium Sulphide.
Al5Lu3O12
Chemical formula for Lutetium Aluminium Garnet.
Alabamine
The name originally proposed for Astatine.
Alanine

C3H7NO2

An a-amino acid. It plays a key role in glucose-alanine cycle between tissues and liver.

Alcian Blue

C56H68Cl4CuN16S4

A phthalocyanine dye that contains copper.

AlCl3
Chemical formula for Aluminium Chloride.
Alcohol
An alcohol is an organic compound with a carbon bound to a hydroxyl group.
Alcohol Brine
A water and alcohol solution, which remains as a liquid below 0°C.
Aldehyde
Prepared by the oxidation of primary alcohols so that the OH group loses its hydrogen to give an oxygen joined by a double bond to a carbon atom.
Aldose
A simple sugar in which the carbonyl carbon atom is an aldehyde.
Aldosterone

C21H28O5

A hormone that causes the tubules of the kidneys to retain sodium and water.

AlF3
Chemical formula for Aluminium Fluoride.
Algaecide
A chemical that when added to a solution prevents the growth of fungus and algae.
AlH3
Chemical formula for Aluminium Hydride.
Aliphatic
An organic compound that does not contain ring structures.
Aliquot
A sample of precisely determined amount taken from a material.
Alkali
A substance that dissolves in water to give a solution of aqueous hydroxide ions that is capable of turning red litmus blue.
Alkali Metal
A metal in group IA of the periodic table that form strongly alkaline hydroxides.
Alkaline
Having a pH greater than 7.
Alkaline Air
An old name for ammonia gas.
Alkaline Earth
An oxide of an alkaline earth metal, which produces an alkaline solution in reaction with water.
Alkaline Earth Metal
A metal in group IIA of the periodic table.
Alkaline Error
A systematic error that occurs when glass electrodes are used to read the pH of an extremely alkaline solution.
Alkalinity
A measure of a material's ability to neutralize acids.
Alkaloid
A class of bitter-tasting, basic organic compounds with nitrogen-containing rings.
Alkane
A series of organic compounds with general formula CnH2n+2.
Alkene
A compound that consists of only carbon and hydrogen, that contains at least one carbon-carbon double bond.
Alkoxide
An ionic compound formed by removal of hydrogen ions from the hydroxyl group in an alcohol using reactive metals.
Alkyl
A molecular fragment derived from an alkane by dropping a hydrogen atom from the formula -CnH2n+1.
Alkyl Halide
An alkyl group attached to a halogen atom.
Alkylphenol
A family of organic compounds obtained by the alkylation of phenols.
Alkyne
A compound that consists of only carbon and hydrogen, that contains at least one carbon-carbon triple bond.
Allo-
A prefix that designates the more stable of a pair of geometric isomers.
Allobar
A form of an element that has isotopic abundances that are different from the naturally occuring form.
Allomer
Substances with different chemical composition but the same crystalline form.
Allosteric Effect
A change in the behaviour of one part of a molecule caused by a change in another part of the molecule.
Allotriomorphic Crystal
A crystal having a normal lattice structure, but with an imperfect outward shape due to the influence of its surroundings.
Allotropy
The reversible phenomenon by which certain metals may exist in more than one crystal structure.
Alloy
A metal produced by mixing other metals.
Allyl
A molecular fragment derived by removing a methyl hydrogen from propene.
Allyl Alcohol
Used in the manufacture of resins and many pharmaceuticals this is a colourless pungent liquid.
Allyl Aldehyde
Alternative name for Acrolein.
Almond Artificial Essential Oil
Alternative name for Benzaldehyde.
AlN
Chemical formula for Aluminium Nitride.
Alpha Radiation
A stream of alpha particles. Alpha rays rapidly dissipate their energy as they pass through materials, and are far less penetrating than beta particles and gamma rays.
Alternating Copolymer
A polymer, composed of two different repeating mers, in which the different mer units systematically alternate positions along the molecular chain.
Alumel
Trade name for an alloy of nickel with up to 5% aluminium, manganese and silicon, used with chromel in K-type thermocouples.

Aluminium
Basis for a number of alloys.
Aluminium 2014
Among the strongest available aluminium alloys, as well as having high hardness. Difficult to weld, as it is subject to cracking.

Aluminium 2024
Aluminium alloy, with copper as the primary alloying element.

Aluminium 5005
Aluminium alloy with good resistance to atmospheric corrosion.

Aluminium 5052
Aluminium alloy, primarily alloyed with magnesium and chromium.

Aluminium 5083
Aluminium alloy with magnesium and traces of manganese and chromium. It is highly resistant to attack by seawater and industrial chemicals. Alloy 5083 retains exceptional strength after welding. It has the highest strength of the non-heat treatable alloys, but is not recommended for use in temperatures in excess of 65°C.

Aluminium 5086
Primarily alloyed with magnesium. It is strengthened by strain hardening, or cold mechanical working of the material. Since heat treatment doesn′t strongly affect the strength, 5086 can be readily welded and retain most of its mechanical strength.

Aluminium 6061
A precipitation hardening aluminium alloy, containing magnesium and silicon as its major alloying elements. Good mechanical properties and exhibits good weldability. It is one of the most common alloys of aluminium for general purpose use.

Aluminium 6063
An aluminium alloy, with magnesium and silicon as the alloying elements. Generally good mechanical properties and is heat treatable and weldable.

Aluminium 6066
An aluminium alloy used in forgings and extrusion for welded structures.

Aluminium 7005
Similar physical properties to 6061 aluminium alloy, except it has a higher density.

Aluminium 7075
An aluminium alloy, with zinc as the primary alloying element. It is strong, with a strength comparable to many steels, and has good fatigue strength and average machinability, but has less resistance to corrosion than many other Al alloys. Its relatively high cost limits its use to applications where cheaper alloys are not suitable.

Aluminium 7079
A high strength aluminium alloy used in the aircraft industry.

Aluminium Bromide

Al2Br6

White or very pale yellow crystalline solid.

Aluminium Bronze
A copper-aluminum alloy with high tensile strength and resistance to corrosion.

Aluminium Chloride
A chloride used as a wood preservative or catalyst.

Aluminium Fluoride

AlF3

White crystalline solid.

Aluminium Hexabromide
Alternative name for Aluminium Bromide.
Aluminium Hexachloride
Alternative name for Aluminium Chloride.
Aluminium Hexaiodide
Alternative name for Aluminium Iodide.
Aluminium Hydride

AlH3

White crystalline solid.

Aluminium Hydroxide
White crystalline compound that occurs naturally as the mineral gibbsite.

Aluminium Iodide

Al2I6

White solid.

Aluminium Nitride

AlN

Bluish white crystalline solid.

Aluminium Oxide

Al2O3

Alminium oxide is the most widely used oxide ceramic, either in pure form or as raw material to be mixed with other oxides.

Aluminium Production
Aluminum metal is produced by electrolysis of aluminum oxide dissolved in a high-temperature molten-salt electrolyte.
Aluminium Sulphide

Al2S3

Yellow or yellow grey powder.

Aluminium Tribromide
Alternative name for Aluminium Bromide.
Aluminium Trichloride
Alternative name for Aluminium Chloride.
Aluminium Triiodide
Alternative name for Aluminium Iodide.
Am
A radioactive element.
Amagat
The unit of density of a gas at stp equal to 44.614774 molm-3.
Amalgam
An alloy that contains mercury.
American Chemical Society
Congressionally chartered independent membership organization which represents professionals at all degree levels and in all fields of chemistry and sciences that involve chemistry.
Americium
A radioactive element. Alpha particle emitter with a half life of 475 years.
Amide
The most stable of all the carbonyl functional groups.
Amine
A class of organic compounds in which one or more of the hydrogen atoms of ammonia have been replaced by other groups of atom.
Aminic Acid
Another name for Methanoic Acid.
Amino Acid
Amino acids are molecules that contain at least one amine group (-NH2) and at least one carboxylic acid group (-COOH).
Aminoacetic Acid
A naturally occurring aliphatic amino acid, also known as glycine.
Aminobenzene
Alternative name for Aniline.
Ammine
A metal ion complex containing ammonia as a ligand.
Ammonia
Obtained from nitrogen using the Haber process and used in the manufacture of fertilizers and explosives.
Ammonium Acetate

CH3COONH4

Derived from the reaction of ammonia and acetic acid.

Ammonium Bicarbonate

NH4HCO3

Used in the food industry as a raising agent for flat baked goods.

Ammonium Carbonate

(NH4)2CO3

Ammonium Chloride

NH4Cl

A clear white water-soluble crystalline salt with a biting, slightly sour taste.

Ammonium Fluoride

NH4F

Crystallizes as small prisms, having a sharp saline taste, and is exceedingly soluble in water.

Ammonium Hydrogen Carbonate
Alternative name for Ammonium Bicarbonate.
Ammonium Hydrogenphosphate

(NH4)2HPO4

Used as a nutrient for the yeast in brewing.

Ammonium Hydroxide
A solution of ammonia in water.
Ammonium Iodide

NH4I

Used in photographic chemicals and some medications.

Ammonium Ion
NH4+ is a cation formed by neutralization of ammonia, which acts as a weak base.
Ammonium Nitrate

NH4NO

The most known chemical property of ammonium nitrate is its combustability. This also makes it a very dangerous compound to work with.

Ammonium Sulphate

(NH4)2SO4

Fine granulated, off white or brown crystals. There may be a slight ammonia like odour. Sulphate of ammonia is a chemical fertilizer.

Amorphography
The branch of science concerned with the determination of amorphous solid structures and their systemmatic classification.
Amorphous
Non-crystalline, without long-range order.
Amount of Substance
The SI unit of the Amount of Substance is the mole.
Amperometry
Determining the concentration of a material in a sample by measuring electric current.
Amphi-
A prefix used to name certain members of a series of geometric isomers or stereoisomers.
Amphipathic
Containing both polar and nonpolar domains.
Amphiprotic Solvent
Solvents that exhibit both acidic and basic properties.
Amphoteric
A substance that can act as either an acid or a base in a reaction.
Amyl Alcohol
The IUPAC name for Butanol.
Amyl Nitrite

C5H11NO2

Employed medically to treat heart diseases such as angina and also to treat cyanide poisoning. It is also used as an inhalant drug that induces a brief euphoria.

Amylopectin
A form of starch made of glucose molecules linked in a branching pattern.
Amylose
A form of starch made of long, unbranched chains of -D-glucose molecules.
Amylum
Another name for starch.
Anaerobic
Occurring in the absence of air or oxygen.
Analyte
The sample constituent whose concentration is sought in a chemical analysis.
Angelic Acid

C5H8O2

A monocarboxylic unsaturated organic acid found in Angelica Archangelica as well as other plants.

Angstrom
It is an old unit used for measuring the wavelength of electromagnetic radiation including visible light and X-rays.
Anhydrous
A compound with all water removed, especially water of hydration.
Aniline
Also known as Phenylamine or aminobenzene.
Anion
Ions with a negative charge.
Anisole
Also known as Methyl Phenyl Ether, an aromatic smell and used in perfumes.
Anthracene
White crystalline with a blue fluorescence used in the manufacture of dyes.
Anthracite
Type of coal with highest carbon content (86% to 98%) and thus highest heat value .

Anthracite Iron
The substance created by the smelting together of anthracite coal and iron ore.

Anthraquinone
Yellow powder derived from Anthracene and used as a dye.
Antichlor
A chemical compound that reacts with chlorine-based bleaches to stop the bleaching.
Antifebrin
Alternative name for Acetanilide.
Antimonic Chloride
Alternative name for Antimony Pentachloride.
Antimonous Chloride
Alternative name for Antimony Trichloride.
Antimonous Oxide
Alternative name for Antimony Trioxide.
Antimonselite
Alternative name for Antimony Triselenide.
Antimony
Elemental antimony is generally found in one of two allotropes and has both metallic and non-metallic properties.
Antimony Hydride

SbH3

Poisonous gas. Also known as Stibine.

Antimony III Chloride
Alternative name for Antimony Trichloride.
Antimony Pentachloride

SbCl5

Toxic, very corrosive and fumes in moist air. It is a reddish-yellow, oily liquid, which is hygroscopic and solidifies after moisture is absorbed.

Antimony Pentafluoride

SbF5

Colourless, viscous liquid that is a valuable Lewis acid and a component of the superacid fluoroantimonic acid, the strongest known acid. Some features that give the compound scientific interest are its Lewis acidity and that it also reacts with almost all known compounds.

Antimony Pentoxide
Alternative name for Antimony V Oxide.
Antimony Perchloride
Alternative name for Antimony Pentachloride.
Antimony Quintachloride
Alternative name for Antimony Pentachloride.
Antimony Sesquioxide
Alternative name for Antimony Trioxide.
Antimony Tetroxide

Sb2O4, SbO2

An inorganic compound.

Antimony Tribromide

SbBr3

Added to polymers such as polyethylene as a fire retardant

Antimony Trichloride

SbCl3

The soft colorless solid with a pungent odor was known to the alchemists as butter of antimony.

Antimony Trifluoride

SbF3

A light grey crystalline material often used in dyeing and pottery.

Antimony Triiodide

SbI3

Used as a dopant in the preparation of thermoelectric materials.

Antimony Trioxide

Sb2O3

The most important commercial compound of antimony.

Antimony Triselenide

Sb2Se3

Exists as the sulfosalt mineral antimonselite.

Antimony V Oxide

Sb2O5

Used as a flame retardant in ABS and other plastics, a flocculant in the production of titanium dioxide and is sometimes used in the production of glass, paint and adhesives.

Antioxidant
Compounds that slow oxidation processes that degrade foods, fuels, rubber, plastic, and other materials.
Antiozidant
Another name for Antiozonant.
Antiozonant
Substances that reverse or prevent severe oxidation by ozone.
Antipyretic
A substance that can lessen or prevent fever.
Antizonant
Substances that reverse or prevent severe oxidation by ozone.
Aprotic Solvent
A solvent that does not act as an acid or as a base.
Aqua Fortis
Ancient name for Nitric Acid, a colourless, corrosive, acid liquid that attacks most metals and other substances.
Aqua Regia
A mixture of nitric and hydrochloric acids used to dissolve gold.
Aquatic Ecotoxicity
The study of how chemicals affect the water environment and the organisms living there.
Aqueous Solubility
The maximum concentration of a chemical that will dissolve in pure water at a reference temperature.
Aqueous Solution
A solution in which water is the dissolving medium or solvent.
Ar
An inert gas that makes up about 1% of the atmosphere.
Aramid
An artificially-made organic material that forms very long and stiff fibres.
Arene
A hydrocarbon that contains at least one aromatic ring.
Argentite
Naturally occuring Silver Sulphide. An important ore of silver.
Argentum
Latin for silver, hence the symbol Ag.
Arginine

C6H14N4O2

A semiessential or conditionally essential amino acid in mammals.

Argon
An inert gas that makes up about 1% of the atmosphere.
Aromatic
Aromatic compounds have strong, characteristic odors.
Aromatic Compound
A compound containing an aromatic ring.
Aromatic Ring
An exceptionally stable planar ring of atoms with resonance structures that consist of alternating double and single bonds, e. g. benzene.
Arrhenius Equation
Variation of rate constant with temperature for several elementary reactions.
Arsenic
A brittle, crystalline solid which tarnishes readily in air and burns in oxygen.
Arsenic III Oxide

As2O3

White crystalline solid, used as an opacifier in glazes.

Arsenic V Oxide

As2O5

White solid.

Arsenical Bronze
An alloy of copper and arsenic in addition to other metals.

Arsenical Copper
An alloy of copper and arsenic in addition to other metals.
Arsine
Old name for Hydrogen Arsenide.
Aryl
A molecular fragment or group attached to a molecule by an atom that is on an aromatic ring.
As
A brittle, crystalline solid which tarnishes readily in air and burns in oxygen.
As2O3
Chemical formula for Arsenic III Oxide.
As2O5
Chemical formula for Arsenic V Oxide.
Asbestos
This description covers a number of fibrous silicate minerals such as calcium magnesium silicate.
Asbestosis
Fibrosis of the lungs caused by inhalation of asbestos fibres.
Ash
The mineral content of a product remaining after complete combustion.
AsH3
Chemical formula for Hydrogen Arsenide.
Asparagine
A natural amino acid that is the amide of aspartic acid.

Aspartic Acid
A nonessential amino acid that is abundant in molasses.
Aspirin
Common name for Acetyl-Salicyclic Acid.
Assay
A quantitative determination of the metal in an ore or alloy.
Astatine
The heaviest halogen and radioactive.
Asymmetric Carbon Atom
A carbon atom that is covalently bonded to four different groups and thus may exist in two different stereospecific configurations.
At
Astatine is heaviest halogen and radioactive.
Atactic
A type of polymer chain configuration wherein side groups are randomly positioned on one side of the polymer backbone or the other.
Atom
The smallest particle of an element that can exist and still retain the ordinary chemical properties of that element.
Atom Percent
Concentration specification on the basis of the number of moles or atoms of a particular element relative to the total number of moles or atoms of all elements within an alloy.
Atomic Nucleus
A tiny, incredibly dense positively charged mass at the heart of the atom - normally abbreviated Nucleus.
Atomic Number
The atomic number (Z) of an element is the number of protons each atom of that element has in its nucleus.
Atomic Orbital
A wavefunction that describes the behavior of an electron in an atom.
Atomic Packing Factor
The fraction of the volume of a unit cell that is occupied by ′hard sphere′ atoms or ions.
Atomic Radius
One half the distance between nuclei of atoms of the same element, when the atoms are bound by a single covalent bond or are in a metallic crystal.
Atomic Theory
An explanation of chemical properties and processes that assumes that tiny particles called atoms are the ultimate building blocks of matter.
Atomic weight
The weighted average mass of the atoms in a naturally occurring element.
Au
Gold is a soft metal with a characteristic yellow colour. It is the most malleable and ductile of any element. It is unaffected by air, water, alkalis and acids.
Aufbau Principle
An approximate procedure for writing the ground state electronic configuration of atoms.
Auricupride

Cu3Au

A natural alloy of copper and gold.

Aurum
Latin for gold, hence the symbol Au.
Autoclave
An airtight vessel constructed of thick-walled steel alloy for carrying out chemical reactions under pressure and high temperatures.
Autoigniting Propellant
Any propellant that ignites by itself without external stimulation.
Autoignition Temperature
The temperature at which combustible materials ignite spontaneously in air.
Auto-Ignition Temperature
Minimum temperature at which the vapour/air mixture over a liquid spontaneously catches fire.
Autoprotolysis
Transfer of a hydrogen ion between molecules of the same substance.
Autoxidation
Oxidation caused by exposure to air.
Auxochrome
A group or substructure in a molecule that influences the intensity of absorption of the molecule.
Avalanche
A cumulative ionization process.
Avogadros Number
N = 6.022045x1023 mol-1
Azeotrope
A solution that does not change composition when distilled.
Azo Compound
The azo group has the general structure Ar-N=N-Ar', where Ar and Ar' indicate substituted aromatic rings.
Azobenzene
Red insoluble crystalline powder.
B
Boron is a non-metallic element which occurs in several allotropes.
B100 Biodiesel
100% biodiesel.
B20 Biodiesel
A blend of biodiesel fuel with petroleum-based diesel where 20% of the volume is biodiesel.
B2O
Chemical formula for Boron Monoxide.
B2O3
Chemical formula for Boron Trioxide.
B6O
Chemical formula for Boron Suboxide.
Ba
Elemental barium does not occur naturally although it has an abundance within the earth’s crust of 500 ppm.
Babbitt
A soft antifriction metal used to line bearings.

Back Titration
Determining the concentration of an analyte by reacting it with a known number of moles of excess reagent.
Background Contamination
The total of the extraneous particles which are introduced in the process of obtaining, storing, moving, transferring and analyzing a fluid sample.
BaCO3
Chemical formula for Barium Carbonate.
Baekeland, Leo Hendrik
Belgian-born American chemist who invented Velox photographic paper and Bakelite.
Bakelite
The first industrial thermoset plastic.
Bakers Salt
Old name for Ammonium Carbonate.
Balanced Equation
A description of a chemical reaction that gives the chemical formulas of the reactants and the products of the reaction, with coefficients introduced so that the number of each type of atom and the total charge is unchanged by the reaction.
Balmer Series
A series of lines in the emission spectrum of hydrogen that involve transitions to the n=2 state from states with n>2.
Bamboo
A natural material with a great strength to weight ratio. It was used in the early construction of aircraft wings and fuselages.

Band
A set of closely spaced energy levels in an atom, molecule, or metal.
BaO
Chemical formula for Barium Oxide.
BaO2
Chemical formula for Barium Dioxide.
Barite
Most commonly found mineral of Barium Sulphate.
Barium
Elemental barium does not occur naturally although it has an abundance within the earth’s crust of 500 ppm.
Barium Carbonate

BaCO3

Chemical used in rat poison, bricks, ceramic glazes and cement.

Barium Dioxide
A white toxic powder obtained by heating barium oxide in air.
Barium Monoxide
An oxide of barium; a whitish toxic powder.
Barium Oxide
An oxide of barium; a whitish toxic powder.
Barium Peroxide
A white toxic powder obtained by heating barium oxide in air.
Barium Protoxide
An oxide of barium; a whitish toxic powder.
Barium Sulphate

BaSO4

A white insoluble solid used as a pigment and filler in plastics. Most commonly found as the mineral Barite.

Barium White
An ancient name for Barium Sulphate.
Baryta
Any of several compounds of barium.
Base
Substance which gives off hydroxide ions (OH-) in solution. In the expression xy, x is called the base and y is the exponent.
Base Hydrolysis Constant
The equilibrium constant for the hydrolysis reaction associated with a base.
Base Number
Another name for Acid Number.
Base Oil
A liquid having a suitable boiling range and viscosity for use in lubricating oils.
Base Pair
Two nucleotides in nucleic acid chains that are paired by hydrogen bonding of their bases.
BaSO4
Chemical formula for Barium Sulphate.
Bath Metal
A cheap bronze made with 21 parts copper and 5 parts zinc. The same as pinchbeck.

Bauxite
An ore of aluminum consisting of moderately pure hydrated alumina.
Bay Salt
Alternative name for Sodium Chloride.
bcc
Abbreviation of body centred cubic. About 15% of all the elements crystallize into this structure.
Be
Beryllium is a light and lustrous metal that is resistant to attack by air or water, even at elevated temperatures
Be3N2
Chemical formula of Beryllium Nitride.
BeBr2
Chemical formula of Beryllium Bromide.
BeCl2
Chemical formula of Beryllium Chloride.
BeF2
Chemical formula of Beryllium Fluoride.
BeI2
Chemical formula of Beryllium Iodide.
Bell Metal
Copper tin alloy with much higher tin content than conventional bronze in order to make it hard and sonorous. It is too brittle to be used for many other applications.

Benzaldehyde

C6H5CHO

A colourless to yellow liquid with an almon like odour. Also known as Benzoic Aldehyde, Almond Artificial Essential Oil, Benzenecarbonal, Benzene Carboxaldehyde and Oil of Bitter Almond.

Benzene
An aromatic hydrocarbon used in the manufacture of many organic compounds.
Benzene Carboxaldehyde
Alternative name for Benzaldehyde.
Benzenecarbonal
Alternative name for Benzaldehyde.
Benzoic Acid

C6H5.COOH

Used as a fruit preservative. At room temperature it is a colourless solid forming glistening needles and plates, sublimes easily and is volatile in steam.

Benzoic Aldehyde
Alternative name for Benzaldehyde.
Benzoin

C14H12O2

An organic compound consisting of an ethylene bridge flanked by phenyl groups and with a hydroxyl and a ketone functional group. It comes as off-white crystals, with a light camphor odor.

BeO
Chemical formula of Beryllium Oxide.
Berkelium
Element with an atomic number of 97.
Beryllia
Alternative name for Beryllium Oxide.
Beryllia Ceramic
Alternative name for Beryllium Oxide.
Beryllium
Beryllium is a light and lustrous metal that is resistant to attack by air or water, even at elevated temperatures
Beryllium Bromide

BeBr2

Hygroscopic and dissolves readily in water.

Beryllium Chloride

BeCl2

White crystalline substance that reacts vigorously and exothermically with water with the evolution of acidic, steamy hydrogen chloride gas. It attacks many metals in presence of water.

Beryllium Copper
Heat treatable copper-beryllium alloy of high strength and hardness. Used for making springs and non-sparking tools.
Beryllium Fluoride

BeF2

A crystalline solid, the principal precursor for the manufacture of beryllium metal.

Beryllium Hydroxide

Be(OH)2

A white solid. One of only a few amphoteric metal hydroxides.

Beryllium Iodide

BeI2

Colourless needle-like crystals that are very hygroscopic and reacts violently with water, forming hydroiodic acid.

Beryllium Nitride

Be3N2

A common component of refractory ceramics.

Beryllium Oxide

BeO

White crystalline oxide that when sintered is very stable and has ceramic characteristics.

Beryllium Telluride

BeTe

A crystalline solid that is a semiconductor with a large energy gap of around 3 eV.

BeTe
Chemical formula of Beryllium Telluride.
Bi
Bismuth is a brittle metal which is silvery in colour with a pink tinge.
Bicarbonate of Ammonia
Alternative name for Ammonium Bicarbonate.
Bidentate
A ligand that has two "teeth" or atoms that coordinate directly to the central atom in a complex.
Biethylene
Another name for 1,3-Butadiene.
Bifunctional Monomer
A monomer unit that has two active bonding positions.
Bihexyl
Another name for Dodecane.
Billon
An alloy of copper and silver with more than 50% copper.

Bimolecular Step
Two species are reacting and form the transition state.
Binary Compound
A compound that contains two different elements.
Biochemical Conversion
The use of enzymes and catalysts to change biological substances chemically to produce other products.
Biochemistry
The chemistry of living things, including the structure and function of biological molecules and the mechanism and products of their reactions.
Biocide
Chemical substance capable of killing living organisms, usually in a selective way.
Biodiesel
Diesel fuel derived from renewable lipid feedstocks, such as vegetable oils and animal fats.
Biodiesel B100
100% (neat) biodiesel. The mono alkyl esters of long chain fatty acids derived from renewable lipid feedstocks, such as vegetable oils and animal fats, diesel engines

Biodiesel B20
A blend of biodiesel fuel with petroleum-based diesel where 20% of the volume is biodiesel.
Biosensor
Either a sensor to detect a biological substance or a sensor which incorporates the use of biological molecules such as antibodies or enzymes.
Biotin
Commonly known as vitamin H.
Biphenyl

C12H10

Notable as a starting material for the production of PCBs, which were once widely used as dielectric fluids and heat transfer agents.

Bischofite
Natural occuring mineral of Magnesium Chloride.
Bismuth
Bismuth is a brittle metal which is silvery in colour with a pink tinge.
Bismuth Chloride

BiCl3

A water soluble crystalline source of bismuth.

Bismuth Germanate

Bi4Ge3O12

Used in detectors in particle physics and nuclear medicine.

Bismuth Subcarbonate

Bi2O2(CO3)

Chemical compound of bismuth containing both oxide and carbonate.

Bismuth Subgallate

C7H5BiO6

Used in medicine as an internal deodorant.

Bitter Salts
Common name for Magnesium Sulphate.
Bittern
Waste solution of magnesium salts and bromides from the preparation of salt from sea-water by evaporation.
Bitumen
A name used to describe many different mixtures of hydrocarbons.
Bk
Berkelium is an element with an atomic number of 97.
Black, Joseph
Scottish chemist who laid the foundations for thermodynamics.
Black Lead
Natural crystalline form of carbon, used to make vessels that resist high temperatures and in making pencils.
Blackett, Patrick Maynard Stuart
English chemist who developed the cloud chamber.
Blast Furnace
A vertical shaft type furnace used for reducing iron ore to pig iron when cast or hot metal for further melting. This product is used in an open hearth or basic oxygen furnaces for production of steel.
Blast Furnace Gas
A by product obtained during the reduction of iron ore by coke in the blast furnace.

Bleach
A dilute solution of sodium hypochlorite or calcium hypochlorite which kills bacteria and destroys coloured organic materials by oxidizing them.
Blind Reference Oil
A reference oil, the identity of which is unknown by the test facility.
Block Copolymer
A linear copolymer in which identical mer units are clustered in blocks along the molecular chain.
Blue Vitriol
An old fashioned name for hydrated copper sulphate.
BN
Chemical formula for Boron Nitride.
Body Centred Cubic
About 15% of elements crystallize with a body centred cubic structure.
Boiling Point
The temperature at which the vapour pressure of a liquid is equal to the external pressure on the liquid.
Boiling Point Elevation
The boiling point of a solution is higher than the boiling point of the pure solvent.
Boiling Range
For a mixture of substances, such as a petroleum fraction, the temperature interval between the initial and final boiling points.
Bond Energy
The energy required to break a given chemical bond.
Bond Length
The average distance between the nuclei of two bonded atoms in a stable molecule.
Bond Order
In Lewis structures, the number of electron pairs shared by two atoms.
Bond Strength
Some measure of how difficult it is to break a chemical bond, for example, a bond energy or a bond enthalpy.
Bonding Energy
The energy required to separate two atoms that are chemically bonded to each other.
Bone
Primarily based on phosphate and carbonate.
Bone Black
An impure animal charcoal prepared from bones and blood.
Boron
Boron is a non-metallic element which occurs in several allotropes.
Boron Monoxide

B2O

Chemical compound of boron and oxygen.

Boron Nitride

BN

Excellent thermal and chemical stability, boron nitride ceramics are traditionally used as parts of high-temperature equipment.

Boron Suboxide

B6O

Due to its short interatomic bond lengths and strongly covalent character, it displays a range of outstanding physical and chemical properties such as great hardness, low mass density, high thermal conductivity, high chemical inertness, and excellent wear resistance.

Boron Trioxide

B2O3

White glassy solid almost always found as the vitreous form; however, it can be crystallized after extensive annealing.

Boyle, Robert
Known for that scientific law named after him.
bp
Abbreviation of boiling point, the temperature at which the vapour pressure of a liquid is equal to the external pressure on the liquid.
Bq
An abbreviation of Becquerel. One Becquerel is that quantity of a radioactive material that will have 1 transformations in one second.
Br
Bromine is an element in the halogen group.
Bragg′s Law
A relationship that stipulates the condition for diffraction by a set of crystallographic planes.
Brakish Water
Water having less salt than sea water, but undrinkable, having salinity values ranging from about 0.5 to 17 parts per thousand.
Branched Polymer
A polymer having a molecular structure of secondary chains that extend from the primary chains.
Brimstone
Ancient name for Sulphur.
Brominated Flame Retardants
A group of chemicals used in plastics and textiles to give flame retardant properties.
Bromine
An element in the halogen group.
Bromoethane

C2H5Br

A colourless volatile liquid that has an ether-like odour.

Bromomethane

CH3Br

A colorless, nonflammable gas with no distinctive smell.

Brösted Acid
A material that gives up hydrogen ions in a chemical reaction.
Brösted Base
A material that accepts hydrogen ions in a chemical reaction.
BTX
Refers to the group of aromatic hydrocarbons: benzene, toluene and xylene.
Buckminsterfullerene

C60

A form of carbon consisting of 60 carbon atoms bound together to make a roughly spherical "buckyball".

Buckyball
A form of carbon consisting of 60 carbon atoms bound together to make a roughly spherical buckyball.
Buffer Solutions
Solutions that resist changes in their pH, even when small amounts of acid or base are added.
Bunsen Burner
A gas burner with adjustable air intake, commonly used in laboratories.
Bunsen, Robert Wilhelm
Introduced the bunsen burner.
Buret
A cylindrical glass tube closed by a stopcock on one end and open on the other, with volume gradations marked on the barrel of the tube, used to precisely dispense a measured amount of a liquid.
Burette
A cylindrical glass tube closed by a stopcock on one end and open on the other, with volume gradations marked on the barrel of the tube, used to precisely dispense a measured amount of a liquid.
Burgers Vector
A vector that denotes the magnitude and direction of lattice distortion associated with a dislocation.
Butadiene

C4H6

An important industrial chemical used as a monomer in the production of synthetic rubber.

Butane

C4H10

An alkane hydrocarbon. Commonly used in compressed form for portable heaters and cookers.

Butanol
An alcohol containing four carbon atoms.

Butene

C4H8

A colourless gas that is present in crude oil as a minor constituent in quantities that are too small for viable extraction.

Butter of Antimony
Alternative name for Antimony Trichloride.
Butter of Zinc
An old name for Zinc Chloride.
Butyl Alcohol
Alternative name for Butanol.
Butylene
Another name for Butene.
C
Carbon occurs naturally in two allotropic forms, namely graphite and diamond.
C10H16
Chemical formula for Adamantane.
C10H16N2O8
Chemical formula for Ethylenediaminetetraacetic Acid.
C10H18O
Chemical formula for Geraniol.
C10H20O
Chemical formula for Menthol.
C10H22
Chemical formula for Decane.
C10H6MgN4O8
Chemical formula for Magnesium Orotate.
C11H24
Chemical formula for Undecane.
C12H10
Chemical formula of Acenaphthene.
C12H10N2
Chemical formula for Azobenzene.
C12H26
Chemical formula for Dodecane.
C12H6O2
Chemical formula for Acenaphthoquinone.
C12H8
Chemical formula for Acenaphthylene.
C13H9N
Chemical formula for Acridine.
C14H10
Chemical formula for Anthracene.
C14H10MgO4
Chemical formula for Magnesium Benzoate.
C14H12O2
Chemical formula for Benzoin.
C14H8O
Chemical formula for Anthraquinone.
C15H21NO6
Chemical formula for Domoic Acid.
C15H24
Chemical formula for Zingiberene.
C16H32
Chemical formula for Cetene.
C16H33OH
Chemical formula for Cetyl Alcohol.
C19H22N2OS
Chemical formula for Acepromazine.
C20H30O2
Chemical formula for Abietic Acid.
C21H28O5
Chemical formula for Aldosterone.
C2H2
Chemical formula for Acetylene.
C2H3N
Chemical formula for Acetonitrile.
C2H3OCl
Chemical formula for Acetyl Chloride.
C2H4O
Chemical formula for Acetaldehyde.
C2H5Br
Chemical formula for Bromoethane.
C2H5Cl
Chemical formula for Chloroethane.
C2H5OH
Chemical formula for ethanol.
C2H5ON
Chemical formula for Acetamide.
C2H6
Chemical formula for Ethane.
C2H6O2
Chemical formula for Ethylene Glycol.
C2HCl3
Chemical formula for Trichlorethene.
C2N2
Chemical formula for Cyanogen.
C36H70MgO4
Chemical formula for Magnesium Stearate.
C3H3ClO
Chemical formula for Acryloyl Chloride.
C3H3N
Chemical formula for Acrylonitrile.
C3H4O
Chemical formula for Acrolein.
C3H4O2
Chemical formula for Acrylic Acid.
C3H5N3O9
Chemical formula for Nitroglycerine.
C3H5NO
Chemical formula for Acrylamide.
C3H6
Chemical formula for Propene.
C3H6O
Chemical formula for acetone.
C3H6O2
Chemical formula for Methyl Acetate.
C3H6O3
Chemical formula for Lactic Acid.
C3H7NO2
Chemical formula for Alanine.
C3H7NO2S
Formula for Cystine
C3H7OH
Chemical formula for Propanol.
C3H8
Chemical formula for Propane.
C3H8O2
Chemical formula for Propylene Glycol.
C3H8O3
Chemical formula for Glycerol.
C4H10
Chemical formula for butane.
C4H10O
Chemical formula for Diethyl Ether.
C4H10O4
Chemical formula for Erythritol.
C4H12N2
Chemical formula for Putrescine.
C4H12Pb
Chemical formula for Tetramethyl Lead
C4H12Sn
Chemical formula for Tetramethyl Tin.
C4H6O3
Chemical formula for Acetic Anhydride.
C4H6O5
Another name for Hydroxybutanedioic Acid.
C4H8
Chemical formula for Butene.
C4H9OH
Chemical formula for Butanol.
C4HF9O4S
Chemical formula for Perfluorosulphonic Acid.
C56H68Cl4CuN16S4
Chemical formula for Alcian Blue.
C5H11NO2
Chemical formula for Amyl Nitrite.
C5H11OH
Chemical formula for Pentanol.
C5H12
Chemical formula for pentane.
C5H12O5
Chemical formula for Xylitol.
C5H8NNaO4
Chemical formula for Monosodium Glutamate.
C5H8O2
Chemical formula for Angelic Acid.
C60
Buckminsterfullerene formed from 60 carbon atoms.
C6H10O4
Chemical formula for Adipic Acid.
C6H12N2O4S2
Chemical formula for Cysteine.
C6H12O6
Chemical formula for Inositol.
C6H13NO2
Chemical formula for Isoleucine.
C6H14
Chemical formula for Hexane.
C6H14N4O2
Chemical formula for Arginine.
C6H14O6
Chemical formula for Mannitol.
C6H5CHO
Chemical formula for Benzaldehyde.
C6H5Cl
Chemical formula for Chlorobenzene.
C6H5 COOH
Chemical formula for Benzoic Acid.
C6H5NO2
Chemical formula for nitrobenzene.
C6H5OH
Chemical formula for Phenol.
C6H6
Chemical formula for benzene, an aromatic hydrocarbon used in the manufacture of many organic compounds.
C6H6O
The chemical formula for phenol, a strong disinfectant.
C6H6O7Mg
Chemical formula for Magnesium Citrate.
C6H7N
Chemical formula for Aniline.
C6H8Cl2O2
Chemical formula for Adipoyl Chloride.
C6H8O7
Chemical formula for Citric Acid.
C6O6Mo
Chemical formula for Molybdenum Hexacarbonyl.
C7H16
Chemical formula for heptane.
C7H16O7
Chemical formula for Volemitol.
C7H5N3O6
Chemical formula for Trinitrotoluene.
C7H8
Chemical formula for toluene.
C7H8O
Chemical formula for Anisole.
C8H10N4O2
A substance found in tea, coffee, and cola that acts as a stimulant.
C8H11N5O3
Chemical formula for Aciclovir.
C8H12MgN2O8
Chemical formula for Magnesium Aspartate.
C8H18
Flammable liquid compounds found in petroleum and natural gas.
C8H20Ge
Chemical formula for Tetraethyl Germanium.
C8H20Pb
Chemical formula for Tetraethyl Lead.
C8H20Sn
Chemical formula for Tetraethyl Tin.
C8H8O
Chemical formula for Acetophenone.
C8H9NO2
Chemical formula for Acetaminophen.
C8H9ON
Chemical formula for Acetanilide.
C9H20
Chemical formula for Nonane.
Ca
Calcium is one of the most abundant metal elements on Earth (41000 ppm).
CaC2
Chemical formula for Calcium Carbide.
CaCl2
Chemical formula for Calcium Chloride
CaCO3
Chemical formula for Calcium Carbonate.
Cadmium
A white metallic element.
Cadmium Oxide
Commonly used in glasses, plastics, ceramics and porcelain enamels as a coloring agent for reds, oranges, and yellows.

Cadmium Sulphate

CdSO4

Colourless, odourless crystals that are freely soluble.

Cadmium Sulphide

CdS

Found as the mineral greenockite, it is used together with selenium to produce strong reds and yellows.

Cadmium Telluride

CdTe

A polycrystalline thin-film photovoltaic material.

Caesium
A soft metal which is often liquid at room temperature due to its relatively low melting point (28.5°C).
Caesium Bromide

CsBr

White crystalline solid.

Caesium Chloride

CsCl

White crystalline solid.

Caesium Fluoride

CsF

White crystalline solid.

Caesium Hydride

CsH

White crystalline solid.

Caesium Iodide

CsI

White crystalline solid.

Caesium Oxide

Cs2O

Yellow to orange crystalline solid.

Caesium Peroxide

Cs2O2

Yellow crystalline solid.

Caesium Sulphide

Cs2S

White to pale yellow crystalline solid.

Caesium Superoxide

CsO2

Yellow to orange crystalline solid.

Caffeine
A substance found in tea, coffee, and cola that acts as a stimulant.
Calamine Brass
Brass produced by a particular alloying technique using calamine (a zinc ore) rather than metallic zinc.

Calcination
A high-temperature reaction whereby one solid material dissociates to form a gas and another solid.
Calcium
One of the most abundant metal elements on Earth (41000 ppm).
Calcium Carbide

CaC2

Usually formed by fusing lime and hard coal in a furnace.

Calcium Carbonate

CaCO3

A white insoluble solid, occuring naturally as chalk, limestone, marble and calcite.

Calcium Chloride

CaCl2

Absorbs moisture from the atmosphere and is used for drying gases.

Calcium Hypochlorite

CaCl(OCl)

More commonly known as bleaching powder.

Calcium Magnesium Acetate
Used as an alternative to road salt.

Calcium Oxide

CaO

Also know as Quicklime.

Calcium Sulphate

CaSO4

Used to make plaster of paris and plaster.

Californium
A man-made element with an atomic number of 98.
Calomel
Another name for Mercury I Chloride.
Calutron
A device that separates isotopes by ionizing the sample.
CaO
Chemical formula for Calcium Oxide.
Carbanion
A negatively charged carbon atom.
Carbide
The old abbreviated name for calcium carbide.
Carbocation
An ion with a positively charged carbon atom.
Carbohydrate
A class of organic compounds including sugars and starches.
Carbolic Acid
Also known as phenol, it is used as a strong disinfectant.
Carbon
Occurs naturally in two allotropic forms, namely graphite and diamond.
Carbon Bisulphide
Alternative name for Carbon Disulphide.
Carbon Black
A form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon. Produced by the incomplete combustion of heavy petroleum products.

Carbon Dioxide
A heavy, colourless gas that is the fourth most abundant constituent of dry air, comprising 0.033% of the total.
Carbon Disulphide
Also known as Carbon Bisulphide used as a solvent in the vulcanization of rubber.
Carbon Hydride Nitride
Alternative name for Hydrogen Cyanide.
Carbon Monoxide
A colourless gas that is very poisonous as it combines with the haemoglobin in blood forming a stable compound so reducing the ability to carry oxygen.
Carbon Nanotubes
Allotropes of carbon with a cylindrical nanostructure.
Carbon Residue
The carbon remaining after evaporating off the volatile portion of a fuel or lubricating oil by heating it in the absence of air under controlled test conditions.
Carbon Tetrachloride
Colourless liquid with a sweet smell used as a solvent.
Carbon Tetrafluoride
Alternative name for Tetrafluoromethane.
Carbonaceous Aerosol
Aerosol consisting predominantly of organic substances and various forms of black carbon.
Carbonado
Carbon that has metamorphosed into its diamond phase but remains black.
Carbonate
An inorganic ion with a charge of -2, containing carbon bound directly to three oxygens in a in a flat triangular arrangement.
Carbonate Water Hardness
Water hardness due to the presence of calcium and magnesium carbonates and bicarbonates.
Carbon-Carbon
A material that consists of 100-percent carbon fibres in a carbon matrix. The material does not contain any binders or epoxy and is coated with a ceramic material.

Carbonic Acid

H2CO3

A weak acid formed by carbon dioxide dissolved in water.

Carbonic Oxide
Old name for Carbon Monoxide.
Carbonyl
A divalent group consisting of a carbon atom with a double-bond to oxygen.
Carboxamide

NH2CONH2

More commonly known as Urea, the main nitrogenous excretion of most animals. It has the distinction of being the first organic compound to have been made in a laboratory (1828). Urea is used in the manufacture of ammonia and carbon dioxide.

Carboxylic Acid
A compound with molecules containing a carboxylic acid group -COOH.
Carboy
A very large bottle.
Carburetted Hydrogen
Old name for Methane.
Carcinogens
Substances known to cause cancer.
Carotene
Carotene is an unsaturated hydrocarbon pigment found in many plants. Carotene is the basic building block of vitamin A.

CaSO4
Chemical formula for Calcium Sulphate.
Cassiterite
Dark coloured mineral that is an important ore of Tin.
Catalyst
Substance that speeds up a chemical process without actually changing the products of reaction.
Catalyst Loading
This refers to the mass of catalyst per unit area.
Catalyst Poisoning
The process of impurities binding to a catalyst and lowering the catalyst′s ability to facilitate the desired chemical reaction.
Catalytic Converter
An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by oxidizing them into carbon dioxide and water or reducing them to nitrogen.
Catalytic Cracking
The use of a catalyst to break down the molecules of the high boiling temperature fractions of crude oil.
Cathode
Electrode where electrons are gained (reduction) in redox reactions.
Cathodic Protection
A means of corrosion prevention.
Cations
Ion with a positive charge.
Cauk
Old name for Barium Sulphate.
Caustic
A substance that causes corrosion.
Caustic Potash
Old fashioned name for Potassium Hydroxide.
Caustic Soda
Alternative name for Sodium Hydroxide.
Cavendish, Henry
English physicist and chemist, discovered hydrogen.
Cawk
Old name for Barium Sulphate.
CCl3F
Chemical formula for Trichlorofluoromethane.
CCl4
Chemical formula for Carbon Tetrachloride.
Cd
Cadmium is a white metallic element.
CdS
Chemical formula for cadmium sulphide.
CdSO4
Chemical formula for Cadmium Sulphate.
CdTe
Chemical symbol for Cadmium Telluride.
Ce
Cerium is a reactive grey metal and is one of the most abundant of the lanthanide group of metals.
Ce2O3
Chemical formula for Cerium III Oxide.
CeCl3
Chemical formula for Cerium III Chloride.
Cellophane
Cellophane is a thin, transparent, waterproof, protective film that is used in many types of packaging.

Cellulose
A polysaccharide made of linked glucose molecules that strengthens the cell walls of most plants.

Cellulose Acetate
Used as a film base in photography, and as a component in some adhesives. It is also used as a synthetic fibre.

Cellulosic Ethanol
Ethanol made from agricultural refuse, grass, wood, municipal waste and a variety of feedstock, which is less expensive and more available than just corn.
Cement
A substance that can be used to build together aggregates of sand or stone into a cohesive structure. May be a single compound or a mixture. May be hydraulic set, air set or chemical set.
Central Atom
In a Lewis structure, usually the atom that is the most electronegative.
CeO2
Chemical formula for Cerium Oxide.
Ceramic
Inorganic, nonmetalllic products for which the interatomic bonding is predominantly ionic.
Ceric Oxide
Another name for Cerium Oxide.
Cerium
A reactive grey metal and is one of the most abundant of the lanthanide group of metals.
Cerium III Chloride

CeCl3

A white hygroscopic solid; It rapidly absorbs water on exposure to moist air to form a hydrate.

Cerium III Oxide

Ce2O3

Gold-yellow coloured oxide of rare earth metal cerium.

Cerium IV Sulphate

Ce(SO4)2

Yellow to yellow/orange chemical compound that is a strong oxidizer.

Cerium Oxide

CeO2

The oxide of the rare earth element cerium. Cerium oxide usually appears as a yellow powder. It is insoluble in water and moderately soluble in strong mineral acids. Used alone or together with other substances as a polishing agent for glass.

Cermet
A composite material consisting of a combination of ceramic and metallic materials.
Cerous Chloride
Chemical formula for Cerium III Chloride.
Cerussite
Mineral form of Lead II Carbonate.
Cetane Index
A calculated value, derived from fuel density and volatility, giving a reasonably close approximation to cetane number.
Cetene

C16H32

An oily hydrocarbon of the ethylene series, obtained from spermaceti.

Cetyl Alcohol

C16H33OH

At room temperature, cetyl alcohol takes the form of a waxy white solid or flakes

Cf
Californium is a man-made element with an atomic number of 98.
CF4
Chemical formula for Tetrafluoromethane.
CH2Cl2
Chemical formula for Dichloromethane.
CH2O2
Chemical formula for for Methanoic Acid.
CH3Br
Chemical formula for Bromomethane.
CH3CH2NH2
Chemical formula for Ethylamine.
CH3Cl
Chemical formula for Chloromethane.
CH3COOC6H4COOH
Chemical formula for Acetyl-Salicyclic Acid.
CH3COOCH2CH3
Chemical formula for Ethyl Acetate.
CH3COONH4
Chemical formula for Ammonium Acetate.
CH3OCH3
Chemical formula for Dimethyl Ether.
CH3OH
A colourless liquid also known as methyl alcohol.
CH4
The chemical formula for methane, the first alkane.
CH4O
Chemical formula for Methyl Alcohol.
Chalk
Common form of Calcium Carbonate.
Change of State
The change in a substance between solid and liquid or between liquid and gas.
Characteristic X-ray
An X-ray having a unique energy that is emitted by an atom during its de-energization after ionization of one of its electrons.
Charcoal
Used to describe different forms of carbon. Formed by heating vegetable or animal matter in the absence of air.
Charge Transfer Reaction
A chemical reaction where an electrical charge is transferred from one reactant to another.
Charged
Possessing a net negative or positive charge.
CHCl3
Chemical formula for chloroform.
Chelate
A stable complex of a metal with one or more polydentate ligands.
Chelating Agent
A ligand that binds to a metal using more than one atom; a polydentate ligand.
Chemical
1. of or pertaining to chemistry. 2. a substance.
Chemical Analysis
Determination of the composition of a sample.
Chemical Bond
A chemical bond is a strong attraction between two or more atoms.
Chemical Change
A chemical change is a dissociation, recombination, or rearrangement of atoms.
Chemical Differentiation
The separation of different elements, often heavier elements from lighter elements, as a consequence of different chemical reactions.
Chemical Energy
Energy stored in the bonds of atoms and molecules eg coal, petrol, biomass.
Chemical Equation
A compact notation for describing a chemical change.
Chemical Formula
A representation of a chemical substance that uses chemical symbols to denote the constituent atoms, and subscripts to indicate the relative numbers of atoms of each type.
Chemical Property
Measurement of a chemical property involves a chemical change.
Chemical Reaction
A process that leads to the transformation of one set of chemical substances to another.
Chemical Set Cement
A cement that sets through reaction or precipitation.
Chemical Stability
The tendency of a substance or mixture to resist chemical change.
Chemical Symbols
Each element has it′s own symbol and these together build up the chemical symbols.
Chemiluminescence
A chemical reaction that releases energy as electromagnetic radiation.
CHG
Abbreviation of Compressed Hydrogen Gas.
Chile Nitre
Another name for Sodium Nitrate.
Chinese Silver
An alloy used for jewellery, 58% copper, 17.5% zinc, 11.5% nickel, 11% cobalt, and 2% silver.

Chinese White
The old name for Zinc Oxide.
Chiral Centre
An atom in a molecule that causes chirality, usually an atom that is bound to four different groups.
Chlorane
Alternative name for Hydrogen Chloride.
Chlorination
The application of chlorine to drinking water, sewage, or industrial waste to disinfect or to oxidize undesirable compounds.
Chlorine
A greenish yellow gas and second in the halogen group.
Chlorobenzene

C6H5Cl

Colourless, flammable liquid is a common solvent and a widely used intermediate in the manufacture of other chemicals.

Chloroethane

C2H5Cl

A colorless, flammable gas or refrigerated liquid with a faintly sweet odour.

Chloroform
Volatile colourless heavy liquid used as an anaesthetic and solvent.
Chlorohydric Acid
Alternative name for Hydrochloric Acid.
Chloromethane

CH3Cl

A colourless extremely flammable gas with a slightly sweet odor. Once commonly used as a refrigerant.

Chromatography
A method for separating mixtures based on differences in the speed at which they migrate over or through a stationary phase.
Chrome Green
Alternative name for Chromium Oxide.
Chrome Yellow
An old name for Lead II Chromate IV.
Chromel
An alloy of nickel with about 10% chromium, used with Alumel in K-type thermocouples.

Chromic Oxide
Alternative name for Chromium Oxide.
Chromium
A bright, blue/white metal with excellent corrosion resistance.
Chromium Dioxide

CrO2

A black crystalline solid.

Chromium IV Oxide
Alternative name for Chromium Dioxide.
Chromium Oxide

Cr2O3

The only stable oxide of chromium. It is a bright to dark green crystalline powder insoluble in alkalis and acids.

Chromium VI Oxide

CrO3

Highly poisonous.

Chromophore
A group or substructure on a molecule that is responsible for the absorption of light.
Cis and Trans Isomers
Isomers related by rotation about a double bond.
Citric Acid

C6H8O7

Natural preservative and also used to add an acidic, or sour, taste to foods and soft drinks.

Cl
Chlorine is a greenish yellow gas and second in the halogen group.
Cl10Mo2
Chemical formula for Molybdenum V Chloride.
Clausius-Clapeyron Equation
Predicts the temperature dependence of vapour pressures of pure liquids or solids.
Cm
Curium is a man-made radioactive element.
CNG
Abbreviation of Compressed Natural Gas.
Co
Cobalt is a hard, grey metal which is ferromagnetic.
CO
Chemical formula for Carbon Monoxide.
CO2
Chemical formula for Carbon Dioxide.
Co2O3
Chemical formula for Cobalt III Oxide.
Coal
A fossil fuel which is made mostly of carbon. It is formed from plants that grew around 150 million years ago.

Coal Gas
Obtained when coal is heated in the absence of air at about 1300°C in either gas ovens or gas-making retorts. A colourless gas with a characteristic odour. It is lighter than air and burns with a long smoky flame.

Coal Tar
A dark brown to black cementitious material produced by the destructive distillation of bituminous coal.

Cobalt
A hard, grey metal which is ferromagnetic.
Cobalt Dichloride
Alternative name for Cobalt II Chloride.
Cobalt II Bromide

CoBr2

Green crystals, used as a catalyst in the oxidation of some organic compounds.

Cobalt II Chloride

CoCl2

Used as an indicator for water as there is a dramatic colour change from CoCl2 which is blue to CoCl2·6H2O which is a deep rose colour.

Cobalt II Nitrate

Co(NO3)2

A red crystalline solid with high solubility of cobalt nitrate makes it a common source of cobalt in metal-organic frameworks and polymers. Deliquescent in moist air.

Cobalt II Oxide

CoO

Olive green to red crystals or greyish or black powder used in ceramics to create blue coloured glazes.

Cobalt III Oxide

Co2O3

A black substance obtained by adding cobalt II nitrate to an aqueous solution of sodium hypochlorite.

Cobalt Monoxide
Alternative name for Cobalt II Oxide.
Cobalt Sesquioxide
Alternative name for Cobalt III Oxide.
Cobalt Trioxide
Alternative name for Cobalt III Oxide.
Cobaltic Oxide
Alternative name for Cobalt III Oxide.
Cobaltous Chloride
Alternative name for Cobalt II Chloride.
Cobaltous Monoxide
Alternative name for Cobalt II Oxide.
Cobaltous Nitrate
Alternative name for Cobalt II Nitrate.
Cobaltous Oxide
Alternative name for Cobalt II Oxide.
CoBr2
Chemical formula for Cobalt II Bromide.
CoCl2
Chemical formula for Cobalt II Chloride.
Cohesion
Attraction between like molecules.
Coke
A hard, dry substance containing carbon that is produced by heating bituminous coal to a very high temperature in the absence of air.

Colligative Properties
Properties of a solution that depend only on the number of particles dissolved in it, not the properties of the particles themselves.
Collision Frequency
The average number of collisions that a molecule undergoes each second.
Collision Theory
A theory that explains reaction rates in terms of collisions between reactant molecules.
Colloid
A heterogeneous mixture composed of tiny particles suspended in another material.
Colourimetry
A method for chemical analysis that relates colour intensity to the concentration of analyte.
Columbium
A name sometimes given to Niobium, a platinum-gray, ductile metal with brilliant luster that is used in alloys, especially stainless steels.
Column Chromatography
A method for separating mixtures.
Columnar Structure
Coarse structure of parallel columns of grains.
Combination Reaction
A reaction in which two or more substances are chemically bonded together to produce a product.
Combustible
Substance that can easily be set on fire and that will burn readily or quickly. Flammable.
Combustion
A chemical reaction between a fuel and an oxidizing agent that produces heat.
Combustion Reaction
The vigorous and exothermic reaction that takes place between certain substances, particularly organic compounds, and oxygen.
Combustion Residue
Carbon and other deposits resulting from combustion.
Common Salt
Sodium Chloride.
Complete Combustion
A combustion reaction that converts all of the fuel′s carbon, hydrogen, sulphur, and nitrogen into carbon dioxide, water, sulphur dioxide, and N2 respectively.
Complete Ionic Equation
A balanced equation that describes a reaction occurring in solution, in which all strong electrolytes are written as dissociated ions.
Complex Compound
Compound contains two or more simpler compounds that can be packed in a definite ratio into a crystal.
Complex Ion
An ion formed by combination of simpler ions or molecules.
Complexing Agent
A ligand that binds to a metal ion to form a complex.
Complexometric Titration
A titration based on a reaction between a ligand and a metal ion to form a complex.
Component
An element or chemical compound that helps make up a material system.
Compound
A pure substance which contains two or more different elements chemically bonded together in stoichiometric proportions.
Compressed Hydrogen Gas
Hydrogen gas compressed to a high pressure and stored at ambient temperature.
Compressed Natural Gas
Natural gas compressed to a volume and density that is practical as a portable fuel supply.
Computational Chemistry
A branch of chemistry concerned with the prediction or simulation of chemical properties, structures, or processes using numerical techniques.
CoN2O6
Chemical formula for Cobalt II Nitrate.
Concentrate
To increase the amount of substance present in a unit amount of mixture.
Concentrated
Having a relatively large amount of substance present in a unit amount of mixture.
Concentration
The amount of substance in a specified space.
Concentration Cell
A voltaic cell in which both compartments contain the same components, but at different concentrations.
Concrete
Building material made from cement, sand, stone and water.

Condensation Polymerization
The formation of polymers by an intermolecular reaction involving at least two monomer species.
Conformers
Molecular arrangements that differ only by rotations around single bonds.
Congener
Elements belonging to the same group on the periodic table.
Congruent Transformation
A transformation of one phase to another that does not involve any change in composition.
Conjugate Acid
A substance which can lose a H+ ion to form a base.
Conjugate Base
A substance which can gain a H+ ion to form an acid.
Conjugated Redox Pair
An electron donor and its corresponding electron acceptor form.
Constantan
An alloy of 40% nickel and 60% copper, with a high volume resistivity and almost negligible temperature coefficient. Used with copper in T-type thermocouples.

Contact Adsorption
Adsorption with the adsorbed molecule or ion being in direct contact with the solid surface.
Contaminant
Any foreign or unwanted substance that can have a negative effect on system operation, life or reliability.
Continuous Spectrum
A plot of the relative absorbance or intensity of emitted light vs. wavelength or frequency that shows a smooth variation, rather than a series of sharp peaks or bands.
CoO
Chemical formula for Cobalt II Oxide.
COOH
Carboxylic acid group.
Coordination Number
The number of atomic or ionic nearest neighbours.
Copernicium

Cp

Scientists from the Centre for Heavy Ion Research in Germany, led by Professor Sigurd Hofmann, discovered copernicium in fusion experiments in 1996.

Copolymer
A polymer that consists of two or more dissimilar mer units in combination along its molecular chains.
Copper
Noted for being ductile and having good electrical and thermal conductivity. It forms the basis of a number of alloys.
Copper I Bromide

CuBr

Yellowish green or white crystalline solid.

Copper I Chloride

CuCl

White crystalline solid. Turns green in moist air.

Copper I Iodide

CuI

White crystalline solid.

Copper I Oxide

Cu2O

A red powder.

Copper I Sulphide

Cu2S

Yellow, red, or brown crystalline solid.

Copper II Bromide

CuBr2

Black crystalline solid. Reacts violently with potassium.

Copper II Carbonate

CuCO3

Green or blue powder forming most of the patina one sees on weathered brass, bronze, and copper. Used as a pigment.

Copper II Hydroxide

Cu(OH)2

Used as a fungicide.

Copper II Oxide

CuO

A black-brown crystalline solid.

Copper II Sulphide

CuS

Blue-black or black crystalline solid.

Copper Indium Diselenide

CuInSe2

A polycrystalline thin-film photovoltaic material.

Copper Plating
The process in which a layer of copper is deposited on the item to be plated by using an electric current.
Copper Sulphate

CuSO4

A water soluble salt used in copper plating.

Copperas
The mineral form of Iron II Sulphate.
Core Electron
Electrons occupying completely filled shells under the valence shell.
Cork
Outer waterproof layer covering most trees and shrubs. The cork material used in flooring and for it′s properties is from the tree Quercus Suber.

Corrosive
Having the power to dissolve. Can burn and destroy living tissue.
Corrosive Sublimate
Another name for Mercury II Chloride.
Coulombic Efficiency
For a rechargeable battery the fraction of the electrical charge stored during charging that is recoverable during discharge.
Coulombic Force
A force between charged particles, such as ions.
Coupled Reactions
Two chemical reactions that have a common intermediate and thus a means of energy transfer from one to the other.
Covalent Bond
Describes the mutual electrostatic attraction of two or more adjacent nuclei for a shared pair of electrons which occupy the same molecular energy level.
Covalent Compound
A compound in which the atoms that are bonded share electrons rather than transfer electrons from one to the other.
Covalent Radius
The radius of atoms obtained from covalent bond lengths.
Cr
Chromium is a bright, blue/white metal with excellent corrosion resistance.
Cr2O3
Chemical formula for Chromium Oxide.
Cracking
The thermal decomposition of the molecules of high molecular mass organic compounds to produce molecules of compounds of lower molecular mass.
C Rate
Battery discharge rate.
Critical Molar Volume
The molar volume at the critical point.
CrO2
Chemical formula for Chromium Dioxide.
Crosslinked Polymer
A polymer in which adjacent linear molecular chains are joined at various positions by covalent bonds.
Crown Glass
A silicate glass containing oxides of sodium and potassium, used in compound lenses and spectacles; harder than flint glass, with low index and low dispersion.

Crown Gold
2 carats of alloy (usually copper sometimes silver) and 22 carats of gold so called from the gold crown of 1526 which used this alloy.

Crude Oil
Unrefined oil as it comes directly from the well.

Cryogenic Gas
A gas that has been liquified by lowering the temperature, usually to a temperature under about -100°C.
Crystal
A material in which the atoms are arranged in a definite geometric pattern.
Crystal Field Splitting Energy
Ligands complexed to a metal ion will raise the energy of some of its d orbitals and lower the energy of others, the difference in energy is called the crystal field splitting energy.
Crystal Field Theory
The colour, spectra, and magnetic properties of metal-ligand complexes can be explained by modelling the effect of ligands on metal′s d orbital energies.
Crystal Orientation
Arrangements in space of the axes of a crystal lattice with respect to a coordinate system.
Crystal Structure
For crystalline materials, the manner in which atoms or ions are arrayed in space. It is defined in terms of the unit cell geometry and the atom positions within the cell.
Crystal System
A scheme by which crystal structures are classified according to unit cell geometry.
Crystalline
The state of a solid material characterized by a periodic and repeating three-dimensional arrays of atoms, ions, or molecules.
Crystallite
A region within a crystalline polymer in which all the molecular chains are ordered and aligned.
Crystallization
Act or process of forming crystals or bodies by elements or compounds solidifying.
Crystals of Silver
Old name for Silver Nitrate.
Cs
A soft metal which is often liquid at room temperature due to its relatively low melting point (28.5°C).
CS2
Chemical formula for carbon disulphide.
Cs2O
Chemical formula for Caesium Oxide.
Cs2O2
Chemical formula for Caesium Peroxide.
Cs2S
Chemical formula for Caesium Sulphide.
CsBr
Chemical formula for Caesium Bromide.
CsCl
Chemical formula for Caesium Chloride.
CsF
Chemical formula for Caesium Fluoride.
CsH
Chemical formula for Caesium Hydride.
CsI
Chemical formula for Caesium Iodide.
CsO2
Chemical formula for Caesium Superoxide.
Cu
Copper is a reddish coloured metal which is malleable and ductile. It has excellent thermal and electrical conductivities and good corrosion resistance.
Cu2O
Chemical formula for Copper I Oxide.
Cu2S
Chemical formula for Copper I Sulphide.
Cubic Nitre
Name for the crystallised form of Sodium Nitrate.
CuBr
Chemical formula for Copper I Bromide.
CuBr2
Chemical formula for Copper II Bromide.
CuCl
Chemical formula for Copper I Chloride.
CuCO3
Chemical formula for Copper II Carbonate.
CuI
Chemical formula for Copper I Iodide.
CuInSe2
Chemical formula for Copper Indium Diselenide.
Cunife
An alloy of copper, nickel, iron, and in some cases cobalt.

CuO
Chemical formula for Copper II Oxide.
Cupric Bromide
Old name for Copper II Bromide.
Cupronickel
An alloy of copper and nickel that is resistant to corrosion.

Cuprum
The old name for Copper and from where the chemical symbol Cu was derived.
Cure
To irreversibly polymerize a thermosetting plastic by subjecting it to a time-temperature profile.
Curium
Man-made radioactive element.
CuS
Chemical formula for Copper II Sulphide.
CuSO4
Chemical formula for Copper Sulphate.
Cyanide Process
A method for separating a metal from an ore.
Cyanocobolamin
Commonly known as vitamin B12.
Cyanoethene
Alternative name for Acrylonitrile.
Cyanogen
Colourless very poisonous gas that smells of bitter almonds.
Cycloalkanes
Saturated compounds containing only carbon and hydrogen atoms in which the carbon backbone forms a ring structure.
Cyclon
Alternative name for Hydrogen Cyanide.
Cysteine

C3H7NO2S

A naturally occurring amino acid with an SH group on its side chain.

Cystine

C6H12N2O4S2

A naturally occurring amino acid with a disulfide bridge group on its side chain, formed by condensation of two cysteine residues.

D2O
Chemical formula for Heavy Water.
dalton
The atomic mass unit is sometimes called the dalton, after John Dalton.
Dalton, John
He developed atomic theory that accounts for the law of conservation of mass, law of definite proportions and law of multiple proportions.
Damps
Any dangerous vapours in caves, mines etc.
Dangling Bonds
A chemical bond associated with an atom on the surface layer of a crystal.
Darcets Alloy
A low melting point alloy.

Debye
Unit of dipole moment.
Decane

C10H22

Decane is one of the components of petrol. Like other alkanes, it is nonpolar and therefore will not dissolve in polar liquids such as water.

Decantation
To a separate the supernatant liquid from a solid precipitate by pouring the liquid off, being careful that all of the solid remains in the vessel.
Decoction
Continuous application of boiling heat to a reaction mixture.
Decomposition Reaction
A reaction in which a compound is broken down into simpler compounds or elements.
Decompounded
Doubly compounded, or composed of three or more substances.
Decrepitation
Rapid physical decomposition of some crystals when heated. Characterized by a crackling noise.
Deflagration
To cause a substance to burn rapidly, with flame.
Degas
Removing air from a liquid, usually by ultrasonic or vacuum methods.
Degenerate Orbital
A set of orbitals are said to be degenerate if they all have the same energy.
Degree of Polymerization
The average number of mer units per polymer chain molecule.
Dehydrator
A separator that removes water from the system fluid.
Deliquescence
Deliquescent compounds absorb so much moisture from the air that they dissolve.
Deliquium
Change of salt from a solid to a fluid state by contact with air only.
Demeon
Alternative name for Dimethyl Ether.
Denatured Alcohol
Poison is added to industrial ethanol so that the tax is not charged for industrial usage.
Density Functional Theory
A model that describes the electronic structure of an atom or molecule by approximating the total energy as a function of electron density.
Dephlegmation
To remove water from a solution, usually one of an acid or alcohol.
Dephlogisticated Air
An old name for oxygen.
Depuration
To free from impurities, purify.
Desalination
Removal of dissolved salts from seawater.
Desiccant
Any absorbent or adsorbent, liquid or solid, that will remove water or water vapor from a material.
Desiccator
A sealed container in which a drying agent is used to dry material that contains water.
Desolvation
In aqueous solution, the release of bound water surrounding a solute such as an enzyme.
Desorption
The opposite process of adsorption.
Desquamation
The process of removing scaly crusts which form on a surface.
Destructive Hydrogenation
The hydrocarbon chains are ruptured and hydrogen is added where the breaks have occurred.
Detonation
Any rapid chemical reaction accompanied by noise and often heat and light, e.g., explosions.
Deuterium
An isotope of hydrogen that contains one neutron and one proton in its nucleus.
Devitrification
The process in which a glass (noncrystalline or vitreous solid) transforms to a crystalline solid.
Dialuminium Hexachloride
Alternative name for Aluminium Chloride.
Dialuminium Trisulphide
Alternative name for Aluminium Sulphide.
Dialysis
The separation of components in a mixture by passing them across a semipermeable membrane.
Diamond
A crystalline form of carbon, made of a network of covalent, tetrahedrally bound carbon atoms.
Diastereomers
Optical isomers that are not mirror images of each other.
Diatomic Molecules
Molecules composed of two atoms eg CO.
Diazonium Salt
A compound with general form Ar-NN+X-, where Ar represents a substituted benzene ring and X- is a halide ion such as chloride.
Diazotization
A reaction that converts an -NH2 group connected to a phenyl ring to a diazonium salt.
Dicaesium Oxide
Old name for Caesium Oxide.
Dicaesium Peroxide
Old name for Caesium Peroxide.
Dicaesium Sulphide
Old name for Caesium Sulphide.
Dichlorodiethyl Sulphide

(CH2CH2Cl)2S

Oily gas used in warfare. Also known as mustard gas or yperite.

Dichlorogermylene
Alternative name for Germanium II Chloride.
Dichloromethane

CH2Cl2

Organic solvent often use to extract organic substances from samples.

Dicobalt Trioxide
Alternative name for Cobalt III Oxide.
Didymium
A mixture of praseodymium and neodymium believed to be an element until 1885.
Diesel
Fossil diesel is produced from the fractional distillation of crude oil between 200°C and 350°C at atmospheric pressure, resulting in a mixture of carbon chains that typically contain between 8 and 21 carbon atoms per molecule.

Diethyl Ether

C4H10O

A clear, colourless, and highly flammable liquid with a low boiling point and a characteristic odor.

Differential Thermal Analysis
A technique that is often used to analyze materials that react or decompose at higher temperatures.
Diffusion
The mixing of two substances caused by random molecular motions.
Diffusion Flux
The quantity of mass diffusing through and perpendicular to a unit cross-sectional area of material per unit time.
Diffusion Rate
The number of randomly moving molecules that pass through a unit area per second.
Dihexyl
Another name for Dodecane.
Dihydrogen Monoxide
More commonly known as water.
Dihydrogen Selenide
Old name for Hydrogen I Selenide.
Dilithium Oxide
Old name for Lithium I Oxide.
Dilithium Peroxide
Old name for Lithium I Peroxide.
Dilute
Having a relatively low concentration.
Dilution
Adding solvent to a solution to lower its concentration.
Dimanganese Heptoxide
Alternative name for Manganese VII Oxide.
Dimercury Dichloride
Another name for Mercury I Chloride.
Dimethyl Ether

CH3OCH3

Simplest ether, it is a colourless gas that is a useful precursor to other organic compounds and an aerosol propellant.

Dimethyl Ketone
Also known as acetone.
Dimethyl Oxide
Alternative name for Dimethyl Ether.
Dimethylbenzenes
Alternatively known as Xylol.
Dipole-Dipole Interaction
Electrostatic attraction between oppositely charged poles of two or more dipoles.
Dipotassium Oxide
Old name for Potassium Oxide.
Dipotassium Peroxide
Old name for Potassium Peroxide.
Diprotic Acid
An acid having two dissociable protons.
Discontinuity
A break in sequence or continuity of anything.
Disilver Sulphide
Old name for Silver Sulphide.
Disinfectant
A substance that kills or stops the growth of microbes.
Dislocation
A linear crystalline defect around which there is an atomic misalignment.
Disodium Oxide
Old name for Sodium Oxide.
Dispersant
An additive that reduces deposits on oil-wetted surfaces primarily through suspension of particles.
Dispersion Forces
Also known as London Forces, an intermolecular attraction force that exists between all molecules.
Displacement Reaction
A reaction in which a fragment of one reactant is replaced by another reactant or by a fragment of another reactant.
Displacements per Atom
A measure of the damage to a crystalline material caused by bombarding the material with energetic particles.
Disproportionation
A reaction involving a substance that produces two different forms of the substance, one more oxidized and the other more reduced than the original.
Dissociation
Breaking down of a compound into its components.
Dissolve
To mix a solid and a liquid to form a solution.
Dissolved Oxygen
The amount of oxygen dissolved in a solvent (usually water).
Distillate
The vapour collected and condensed from a distillation.
Distillation
A process used to separate a liquid from a solution.
Distillation Per Ascensum
Distillation with the collecting vessel above the heated vessel.
Distillation Per Decensum
Any distillation where the collecting vessel is below the heated vessel.
Distillation Per Obliquium
Distillation in a retort used for substances of relatively low vapor pressure and other properties that make distillation difficult.
Distillation with Addition
Adding some substance prior to distillation that will aid the process.
Disulfane
Old name for Hydrogen Persulphide.
Disulphur Dioxide

S2O2

Unstable with a lifetime of a few seconds.

Divalent
Binds to two other things: atoms, molecules, ions, or electrons.
Divalent Anion
An ion with a charge of -2.
Divalent Cation
An ion with a charge of +2.
Divinyl
Another name for 1,3-Butadiene.
Dodecane

C12H26

A thick, oily liquid of the paraffin series. It is used as a solvent, distillation chaser and is also the average component of diesel fuel.

Domoic Acid

C15H21NO6

Domoic acid is a toxic amino acid produced by certain species of algae.

Doping
The intentional alloying of semiconductor materials with controlled concentrations of donor or acceptor impurities
Double Bond
When an atom is bonded to another atom by two sets of electron pairs.
Double Displacement
A reaction in which two reactants trade fragments.
Drinking Water
Water of sufficiently high quality that it can be consumed or used without risk of immediate or long term harm.
Drug
A biologically active compound or mixture used to cure, prevent, or detect disease, to control biological processes, or to alter mental state.
Dry Bulb Thermometer
A thermometer used to measure the ambient temperature.
Dry Cell
A electrolytic cell also known as a Leclanché cell that uses a moist paste rather than a liquid as an electrolyte.
Dulcification
Any process in which a caustic substance is rendered less corrosive.
Duodecane
Another name for Dodecane.
Dutch Metal
A form of brass being an alloy of copper, 84% and zinc 16%.

Dy
Dysprosium is a silvery metal of the lanthanide group. It is relatively stable in air, reacts violently with water and dissolves in acids.
Dy2O3
Chemical formula for Dysprosium III Oxide.
Dymel A
Alternative name for Dimethyl Ether.
Dynamic Equilibrium
Equilibrium which includes inertial forces.
Dynamite
A blasting explosive, based on nitroglycerine, but much safer to handle than nitroglycerine alone.
Dysprosium
A silvery metal of the lanthanide group. It is relatively stable in air, reacts violently with water and dissolves in acids.
Dysprosium III Oxide

Dy2O3

A white, slightly hygroscopic powder.

E10 Ethanol
Ethanol mixture that contains 10% ethanol, 90% unleaded gasoline.
E85
Refers to a fuel blend of 85 percent ethanol and 15 percent gasoline.
E85 Ethanol
Refers to a fuel blend of 85 percent ethanol and 15 percent gasoline.
Ebulliometry
Determination of average molecular weight of a dissolved substance from the boiling point elevation of the solution.
Ebullition
The agitating, bubbling action of a liquid that is undergoing rapid, active boiling.
Effective Nuclear Charge
The nuclear charge experienced by an electron when other electrons are shielding the nucleus.
Effervescence
The rapid escape of gas from a liquid, usually due to chemical action.
Efflorescent
Efflorescent substances lose water of crystallization to the air.
Effusion
Movement of gas molecules through a small opening.
Einsteinium
An artificial radioactive element found in the debris of an H bomb.
Elastomer
A polymeric material that may experience large and reversible elastic deformations.
Electric Dipole
An object whose centres of positive and negative charge do not coincide.
Electric Dipole Moment
A measure of the degree of polarity of a polar molecule.
Electrochemistry
The study of the interchange of chemical and electrical energy.
Electrodeposition
The deposition of a substance on an electrode by passing electric current through an electrolyte.
Electrodes
Device that moves electrons into or out of a solution by conduction.
Electrokinetic Potential
Electric potential across all phase boundaries between solids and liquids, also known as the Zeta Potential.
Electromotive Series
The electrode potential of a material according to decreasing tendency to release electrons with hydrogen as zero.
Electron Affinity
The measure of an atom′s tendency to gain an electron.
Electron Configuration
A list showing how many electrons are in each orbital or subshell.
Electron Geometry
Structure of a compound based on the arrangement of its electrons.
Electron Shell
A group of electrons which have a common energy level that forms part of the outer structure of an atom.
Electronegative
For an atom, having a tendency to accept valence electrons; also a term to describe non-metallic elements.
Electronic Structure
The distribution of electrons in the material and the energies related to changes in this distribution.
Electrophoresis
The migration of colloidal particles dispersed in a fluid, under the influence of an electric field.
Electropositive
For an atom, having a tendency to release valence electrons.
Electrorefining
A method for purifying a metal using electrolysis.
Electrostatic Interactions
Attractions between opposite charges or repulsions between like charges that grow stronger as the charges become closer to each other.
Electrovalence
The valence as determined by the electrons lost or gained by the elements reacting to form a compound.
Electrum
An alloy of 75% gold and 25% silver along with small quantities of other metals such as copper.

Element
A pure substance which cannot be broken down into simpler substances by chemical means.
Element Symbol
An international abbreviation for element names, usually consisting of the first one or two distinctive letters in element name.
Elementary Reaction
A reaction that occurs in a single step.
Elementary Step
Reaction mechanisms are broken down into elementary steps.
Emissions
The gases and airborne particles produced during combustion.
Emollient
A substance added to a formulation that gives it softening ability.
Empirical Law
A law strictly based on experiment, which may lack theoretical foundation.
Emulsion
A colloid formed from tiny liquid droplets suspended in another, immiscible liquid. E.g. Milk.
Enantiomers
Stereoisomers that are nonsuperimposable complete mirror images of each other.
Endergonic
Refers to a reaction for which the free energy of the system increases.
Endothermic
Reaction that absorbs heat from its surroundings as the reaction proceeds.
Endpoint
The experimental estimate of the equivalence point in a titration.
Energy Density
Characteristic parameter of a battery/electrical power source indicating the amount of electrical energy stored per unit weight or volume.
Engineering and Physical Sciences Research Council
EPSRC funds research and postgraduate training in engineering and the physical sciences at universities and other organisations throughout the UK.
Enthalpy of Formation
The enthalpy change when 1 mole of a substance is formed from the elements in their standard states.
Enzyme
Protein or protein-based molecules that speed up chemical reactions occurring in living things.
Epsom Salts
Common name for Magnesium Sulphate.
EPSRC
Engineering and Physical Sciences Research Council
Equilibrium Expressions
The expression giving the ratio between the products and reactants.
Equivalence Point
Occurs when the moles of acid equal the moles of base in a solution.
Er
Erbium is a silvery grey metal that is a member of the lanthanide group of elements.
Er2O3
Chemical formula for Erbium III Oxide.
ErB4
Chemical formula for Erbium III Boride.
ErB6
Chemical formula for Erbium Hexaboride.
Erbium
A silvery grey metal that is a member of the lanthanide group of elements.
Erbium Hexaboride

ErB6

A rare earth hexaboride compound which has a calcium hexaboride crystal structure.

Erbium III Boride

ErB4

It is hard and has a high melting point.

Erbium III Bromide

ErBr3

A violet crystalline solid which is highly soluble in water.

Erbium III Chloride

ErCl3

The erbium(III) salt of hydrochloric acid, is a violet solid used for the preparation of erbium metal.

Erbium III Oxide

Er2O3

Pink color with a cubic crystal structure. Under certain conditions erbium oxide can also have a hexagonal form.

ErBr3
Chemical formula for Erbium III Bromide.
ErCl3
Chemical formula for Erbium III Chloride.
Errors
No measurement is exact, they all contain some degree of errors.
Erythrene
Another name for 1,3-Butadiene.
Erythritol

C4H10O4

It is 60–70% as sweet as table sugar yet it is almost noncaloric, does not affect blood sugar, does not cause tooth decay, and is partially absorbed by the body, excreted in urine and feces.

Es
Einsteinium artificial radioactive element found in the debris of an H bomb.
Essential Oil
Any oil that smells the same as the vegetable from which it was obtained and has a low boiling point.
Ester
Compound formed by the reaction between an alcohol and an acid, with the elimination of water.
Ethanal
Also known as acetaldehyde, it is a colourless fruity smelling liquid that with further oxidation forms acetic acid.
Ethanamide
Also known as Acetamide.
Ethane

C2H6

Second member of the alkane series, a colourless, odourless gas.

Ethanenitrile
Also known as Acetonitrile.
Ethanoic Acid
Alternative name for Acetic Acid.
Ethanol

C2H5OH

Prepared by the fermentation of sugar.

Ethanol E10
Ethanol mixture that contains 10% ethanol, 90% unleaded gasoline.

Ethanol E85
Refers to a fuel blend of 85 percent ethanol and 15 percent gasoline.

Ethanol E93
Ethanol mixture that contains 93% ethanol, 5% methanol and 2% kerosene, by volume.

Ethanol E95
Ethanol/gasoline mixture that contains 95% denatured ethanol and 5% gasoline, by volume.

Ethanoyl Chloride
Also known as Acetyl Chloride.
Ethene
Alternative name for Chloroform.
Ether
A class of organic compounds that contain an ether group which is an oxygen atom connected to two alkyl or aryl groups.
Etherification
Oxygenation of an olefin by methanol or ethanol.
Ethyl
The monovalent radical -C2H5
Ethyl Acetate

CH3COOCH2CH3

A flammable liquid with a fruity odour, used in flavourings and as a solvent.

Ethyl Bromide
Alternative name for Bromoethane.
Ethyl Chloride
Alternative name for Chloroethane.
Ethyl Ether
Another name for Diethyl Ether.
Ethyl Oxide
Another name for Diethyl Ether.
Ethyl Tertiary Butyl Ether
A fuel oxygenate used as a gasoline additive to increase octane and reduce engine knock.

Ethylamine

CH3CH2NH2

Widely used in chemical industry and organic synthesis, it has a strong ammonia-like odor.

Ethylene
Also known as Ethene this is a colourless inflammable gas with a sweet smell used as an anaesthetic and in the manufacture of polythene.
Ethylene Aldehyde
Alternative name for Acrolein.
Ethylene Glycol

C2H6O2

An odorless, colourless, syrupy, sweet-tasting liquid. Ethylene glycol is only weakly toxic, but cases of poisonings are not uncommon.

Ethylene Vinyl Acetate
The copolymer of ethylene and vinyl acetate.

Ethylenecarboxylic Acid
Alternative name for Acrylic Acid.
Ethylenediaminetetraacetic Acid

C10H16N2O8

A polydentate ligand that tightly complexes certain metal ions.

Ethyne
Also known as Acetylene, used for welding as the flame temperature is roughly 3300°C when burnt with oxygen.
Eu
A europium is a ductile silvery metal which reacts rapidly with air and water.
Europium
A ductile silvery metal which reacts rapidly with air and water.
Eutectic Alloy
An alloy that changes directly from a solid to a liquid with no plastic or semiliquid state.
Eutectic Mixture
A mixture of two or more substances with melting point lower than that for any other mixture of the same substances.
Eutectic Point
The melting point of a eutectic mixture.
EVA
Common abbreviation of Ethylene Vinyl Acetate.
Excitotoxin
An excitotoxin is a toxic molecule that stimulates nerve cells so much that they are damaged or killed.
Exergonic
Refers to a reaction for which the free energy of the system decreases.
Exothermic
Reaction that gives off heat to the environment.
Experimental Yield
The measured amount of product produced in a chemical reaction.
Extensive Properties
Properties which are dependent on the amount of the substance.
F
Fluorine is a pale greenish yellow gas that is the first in the halogen group.
Face Centred Cubic
Roughly 20% of the elements crystallize with face centred cubic structures.
Facilitated Diffusion
Diffusion of a molecule across a biological membrane via a protein transporter down a concentration gradient.
Faints
Name given to the impure spirit which comes over first and last in distillation.
Famous Scientists & Engineers
Lists all the Famous Scientists & Engineers in the Encyclopaedia
Fatigue
An important mode of failure of engineering components subjected to dynamic stresses.
Fatty Acid
Carboxylic acids with long hydrocarbon side chains.
Fe
Iron is one of the most abundant metallic elements (41000 ppm) and probably one of the most important, being used on the largest scale of any metal.
Fe2O3
Chemical formula for Iron III Oxide.
FeCl2
Chemical formula for Iron II Chloride.
FeCl3
Chemical formula for Iron III Chloride.
FeO
Chemical formula for Iron II Oxide.
Fermentation
A class of biochemical reactions that break down complex organic molecules into simpler materials.
Fermium
A man-made element with an atomic number of 100.
Ferric Oxide
Old name for Iron III Oxide.
Ferroelectric
A dielectric material that may exhibit polarization in the absence of an electric field.
Ferroin

C36H24FeN6+2

A blood-red complex of Fe2+ ion with 1,10-phenanthroline, used as a redox indicator. Ferroin changes from red to pale blue when oxidized.

Ferromagnetism
Permanent and large magnetizations found in some metals (e.g., Fe, Ni, and Co), which result from the parallel alignments of neighboring magnetic moments.
Ferrous Chloride
Old name for Iron II Chloride.
Ferrous Metal
A metal alloy in which iron is the major ingredient.
Ferrous Oxide
Old name for Iron II Oxide.
Ferrous Sulphide
Old name for Iron Sulphide.
Ferrum
Latin for iron, hence the symbol Fe.
FeS
Chemical formula for Iron Sulphide.
FeS2
Chemical formula for Iron II Sulphide.
FeSO4
Chemical formula for Iron II Sulphate.
Fibre
Any material that has been drawn into a cylinder with a length-to-diameter ratio greater than about ten.
Fields Metal
A low melting point alloy. 51% Indium, 32.5% Bismuth, and 16.5% Tin.
A non-toxic replacement for Wood's Metal.
Filler
An inert foreign substance added to a matrix to improve or modify its properties.
Fire Air
An old name given to pure oxygen.
Fire Damp
The gases found naturally in coal are a mixture of methane and other hydrocarbons. Given the name as they are highly combustible when mixed with air.
First Order Reaction
The sum of concentration exponents in the rate law for a first order reaction is one. Many radioactive decays are first order reactions.
Fischer-Tropsch
A method discovered in 1923 by the German coal researchers Franz Fischer and Hans Tropsch, for the synthesis of hydrocarbons and other aliphatic compounds.
Flame Test
A test to identify some metals, e.g. with sodium the flame turns orange.
Flammability Limits
The flammability range of a gas is defined in terms of its lower flammability limit (LFL) and its upper flammability limit (UFL).
Flammable
Substance that can easily be set on fire and that will burn readily or quickly.
Flash Point
The temperature when vapour pressure of a substance becomes high enough to allow the air/vapour layer over the substance to be ignited.
Flint Glass
An optical glass with higher dispersion and higher refractive index than crown glass; a heavy, brilliant glass, softer than crown glass.

Florentine Bronze
A modern term for an alloy usually formed as a mixture of aluminium or tin (<10%) and copper (>90%).

Flowers of Antimony
Alternative name for Antimony Trioxide.
Fluorescence
The property of a material whereby it emits visible light when it is illuminated by ultraviolet light.
Fluorine
A pale greenish yellow gas that is the first in the halogen group.
Fluorotrichloromethane
Alternative name for Trichlorofluoromethane.
Fm
Fermium is a man-made element with an atomic number of 100.
Foam
A colloid in which bubbles of gas are suspended in a solid or liquid.
Fools Gold
Name given to Iron II Sulphide due to its colour and texture.
Formaldehyde

H2CO

Used widely by industry to manufacture building materials and numerous household products. It is also a by-product of the incomplete combustion of carbo containing materials.

Formation Reaction
A reaction that forms one mole of a compound from its elements in their most stable forms.
Formic Acid
Another name for Methanoic Acid.
Formic Anammonide
Alternative name for Hydrogen Cyanide.
Formonitrile
Alternative name for Hydrogen Cyanide.
Formula Unit
One formula weight of a compound.
Formula Weight
The formula weight is the sum of the atomic weights of the atoms in an empirical formula.
Formyl Trichloride
Alternative name for Chloroform.
Formylic Acid
Another name for Methanoic Acid.
Fossil Fuel
A fuel such as coal, oil or natural gas that was formed through the decomposition of ancient plant and animal life.
Fr
Francium is the heaviest alkali metal with no stable isotopes.
Fractional Distillation
A technique for separation of liquid mixtures by distillation that uses a tower attached to a flask containing the mixture to perform multiple distillations.
Francium
The heaviest alkali metal with no stable isotopes.
Free Energy Change
The amount of free energy released (negative ΔG) or absorbed (positive ΔG) in a reaction at constant temperature and pressure.
Free Radical
A molecule with an odd number of electrons.
Freeze
To change from a liquid to a solid by cooling.
Frenkel Defect
In an ionic solid, a cation-vacancy and cation-interstitial pair.
Freon-10
Alternative name for Carbon Tetrachloride.
Freon-11
Alternative name for Trichlorofluoromethane.
Freon-14
Alternative name for Tetrafluoromethane.
Fuel
Any substance burned for heat or power.
Fuel Additives
Chemicals added to fuel in very small quantities to improve and maintain fuel quality and/or to lower emissions.
Fuel Cell
A device that converts the chemical energy obtained from a redox reaction directly into electrical energy.
Fuel Processor
Device used to generate hydrogen from fuels such as natural gas, propane, gasoline, methanol, and ethanol for use in fuel cells.
Fugacity
The expression of activity for a component in a mixture of gases.
Fullerene
A form of carbon consisting of 60 carbon atoms bound together to make a roughly spherical buckyball.
Fulmination
Any very rapid reaction which produces heat, light, and noise - explosions.
Functional Group
A substructure that imparts characteristic chemical behaviours to a molecule, for example, a carboxylic acid group.
Furanose Ring
A five-membered cyclic hemiacetal or hemiketal of a carbohydrate.
Fused Quartz
The glassy isotropic form of quartz.
Fused Silica

SiO2

The glassy isotropic form of quartz.

Ga
Gallium is one of four metals which can be liquid at room temperature
Ga2I6
Chemical formula for Gallium III Iodide.
Ga2O3
Chemical formula for Gallium III Oxide.
Ga2Se3
Chemical formula for Gallium III Selenide.
Ga2Te3
Chemical formula for Gallium III Telluride.
GAA
Abbreviation of Glacial Acetic Acid.
GaAs
Chemical formula for Gallium Arsenide.
GaBr3
Chemical formula for Gallium III Bromide.
GaCl3
Chemical formula for Gallium III Chloride.
Gadolinium
A silvery white metal which is ductile and malleable. It is stable in a dry atmosphere but forms an oxide coating when exposed to moist air.
Gadolinium III Chloride

GdCl3

A colourless, hygroscopic, water-soluble solid.

GaF3
Chemical formula for Gallium III Fluoride.
Galena
A Lead Sulphide and the most common ore of lead.
Gallium
One of four metals which can be liquid at room temperature.
Gallium Arsenide

GaAs

A crystalline, high-efficiency compound used to make certain types of solar cells and semiconductor material.

Gallium II Selenide

GaSe

Has been used as a non-linear optical material.

Gallium II Telluride

GaTe

Made by reacting the elements or by metal organic vapour deposition.

Gallium III Bromide

GaBr3

White powder that is soluble in water.

Gallium III Chloride

GaCl3

The main precursor to most derivatives of gallium and a reagent in organic synthesis.

Gallium III Fluoride

GaF3

White solid.

Gallium III Hydroxide

Ga(OH)3

The normal form of Gallium in the Earth′s crust.

Gallium III Iodide

Ga2I6

The most common iodide of gallium.

Gallium III Oxide

Ga2O3

White crystalline powder prepared by thermal decomposition of gallium salts.

Gallium III Selenide

Ga2Se3

P-type semiconductor. Reddish-black crystals with a slight garlic odour.

Gallium III Telluride

Ga2Te3

Used as a semiconductor.

Gallium Monoselenide
Alternative name for Gallium II Selenide.
Gallium Nitride

GaN

A binary III/V direct bandgap semiconductor commonly used in bright light-emitting diodes.

Gallium Phosphide

GaP

Used in the manufacture of low-cost red, orange, and green light-emitting diodes.

Gallium Sesquioxide
Alternative name for Gallium III Oxide.
Gallium Tribromide
Alternative name for Gallium III Bromide.
Gallium Trichloride
Alternative name for Gallium III Chloride.
Gallium Trifluoride
Alternative name for Gallium III Fluoride.
Gallium Trihydroxide
Alternative name for Gallium III Hydroxide.
Gallium Triiodide
Alternative name for Gallium III Iodide.
Gallium Trioxide
Alternative name for Gallium III Oxide.
Gallium Triselenide
Alternative name for Gallium III Selenide.
Galvanic Cell
A cell in which chemical change is the source of electrical energy.
Galvanic Couple
A pair of dissimilar conductors, commonly metals, in electrical contact.
Galvanic Current
The electric current that flows between metals or conductive nonmetals in a galvanic couple.
Gamma Iron
The face-centered cubic form of pure iron, stable from 910 to 1400°C.
GaN
Chemical formula for Gallium Nitride.
GaP
Chemical formula for Gallium Phosphide.
Gas
Matter with no definite shape or volume.
Gas Constant
Molar Gas Constant, R = 8.31441 JK-1mol-1
Gas to Liquid Technology
Gas-to-liquid conversion technologies that use chemical or physical means to convert natural gas to a liquid form suitable for road transport or direct use.
GaSe
Chemical formula for Gallium II Selenide.
Gasification
A process for converting materials such as coal, petroleum, or biomass, into carbon monoxide and hydrogen by reacting the raw material at high temperatures with a controlled amount of oxygen.
GaTe
Chemical formula for Gallium II Telluride.
Gay-Lussac, Joseph Louis
Developed the law of volumes concerning the combination of gases and discovered boron.
Gay-Lussac′s Law
When gases react, they do so in a definite proportion by volume, if the volumes are measured at the same pressure and temperature.
Gd
Gadolinium is a silvery white metal which is ductile and malleable. It is stable in a dry atmosphere but forms an oxide coating when exposed to moist air.
GdCl3
Chemical formula for Gadolinium III Chloride.
Ge
Germanium is a silvery white brittle metalloid member of the carbon group of elements. Its physical properties being similar to those of silicon.
GeCl2
Chemical formula for Germanium II Chloride.
GeCl4
Chemical formula for Germanium IV Chloride.
GeH4
Chemical formula for Germane.
Gel
A sol in which the solid particles fuse or entangle to produce a rigid or semirigid mixture.
Gel Cell
A technique for sealed lead-acid batteries. The electrolyte solution is in a gel form, usually silica gel, instead of plain liquid.
Gel Filtration
A chromatographic procedure for the separation of a mixture of molecules on the basis of size.
GeO
Chemical formula for Germanium Monoxide.
GeO2
Chemical formula for Germanium IV Oxide.
Geochemistry
The study of materials and chemical reactions in rocks, minerals, magma, seawater, and soil.
Geometric Isomer
Molecules that have the same molecular formula and bond connections, but distinctly different shapes.
Geraniol

C10H18O

A clear to pale-yellow oil that is insoluble in water, but soluble in most common organic solvents.

German Silver
This describes a number of alloys that contain copper (25 to 50%), zinc (10 to 35%) and nickel (5 to 35%) within the limits given.
Germane

GeH4

Used in the semiconductor industry for the epitaxial growth of germanium.

Germania
Another name for Germanium IV Oxide.
Germanium
A silvery white brittle metalloid member of the carbon group of elements. Its physical properties being similar to those of silicon.
Germanium Chloride
Alternative name for Germanium IV Chloride.
Germanium Dichloride
Alternative name for Germanium II Chloride.
Germanium Dioxide
Another name for Germanium IV Oxide.
Germanium Disulphide
Alternative name for Germanium IV Sulphide.
Germanium II Chloride

GeCl2

White-pale yellow solid which on warming gives brown germanium monoxide.

Germanium II Selenide

GeSe

Black crystalline powder having orthorhombic crystal symmetry.

Germanium IV Chloride

GeCl4

Colourless liquid used as an intermediate in the production of purified germanium metal.

Germanium IV Oxide

GeO2

Refractive index and optical dispersion properties make it useful as an optical material for wide-angle lenses and in optical microscope objective lenses.

Germanium IV Sulphide

GeS2

White crystalline solid.

Germanium Monoxide

GeO

Prepared as a yellow sublimate at 1000°C by reacting GeO2 with Ge metal.

Germanium Selenide
Alternative name for Germanium II Selenide.
Germanium Telluride

GeTe

Shows semimetallic conduction and ferroelectric behaviour.

Germanium Tetrachloride
Alternative name for Germanium IV Chloride.
Germanium Tetrahydride
Alternative name for Germane.
Germanomethane
Alternative name for Germane.
GeS2
Chemical formula for Germanium IV Sulphide.
GeSe
Chemical formula for Germanium II Selenide.
GeTe
Chemical formula for Germanium Telluride.
Gibbs Free Energy
A function of the system related to Suniv. It is used to determine the spontaneity of a reaction.
Gibbsite
White crystalline mineral consisting of aluminum hydroxide; a constituent of bauxite and a source of alumina.
Gilding Metal
A form of brass, comprising 95% copper and 5% zinc. Used to make items that were to be gilded.

Glance
A mineral with a glassy appearance.
Glass
Transparent or translucent substance that is physically neither a solid or liquid. It is made by fusing certain types of sand (silica).
Glass Ceramic
A fine-grained crystalline material that was formed as a glass and subsequently devitrified (crystallized).
Glass Transition Temperature
The temperature at which, upon cooling, a noncrystalline ceramic or polymer transforms from a supercooled liquid into a rigid glass.
Glucose
A sugar. It is made by plants during photosynthesis.

Glue
Cement or adhesive that is used to fix two or more parts together.
Glycerol
Thick sweet liquid used in the manufacture of explosives.
Glycine

NH2CH2COOH

A naturally occurring aliphatic amino acid, found in large quantities in gelatin.

Gold
A soft metal with a characteristic yellow colour. It is the most malleable and ductile of any element. It is unaffected by air, water, alkalis and acids.
GOx
Abbreviation of Gaseous Oxygen.
Graham′s Law
The rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.
Gram Molecule
The mass in grams of a substance numerically equal to its molecular weight.
Graphene
An allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice.

Graphite
An amorphous form of carbon, made of carbon atoms bound hexagonally in sheets.

Green Vitriol
Hydrated Iron II Sulphate.
Greenockite
Mineral, main source of cadmium sulphide.

Group
A vertical column in the periodic table.
Guaranine
An alkaloid extracted from guarana, the same as Caffeine.
Gunmetal
This is a copper-tin alloy, similar to bronze, used where resistance to corrosion and/or wear required. Composition: 88% copper, 8% tin, 4% zinc.

Gunpowder
Any of several low-explosive mixtures.
Gy
An abbreviation of gray, the amount of energy actually absorbed in some material, and is used for any type of radiation and any material.
Gypsum
The old name for Calcium Sulphate.
H
Hydrogen is the least dense element. It has metallic and non-metallic properties.
H2C2O4
Chemical formula for Oxalic Acid.
H2CO
Chemical formula for Formaldehyde.
H2CO3
Chemical formula for Carbonic Acid.
H2O
Chemical formula for water
H2O2
Hydrogen peroxide.
H2S
Hydrogen sulphide.
H2Se
Chemical formula for Hydrogen I Selenide.
H2SO3
Chemical formula for Sulphurous Acid.
H2SO4
Chemical formula for Sulphuric Acid.
H2Te
Chemical formula for Hydrogen I Telluride.
H3PO4
Chemical formula for Phosphoric Acid.
ha
An abbreviation of hectare, a derived SI unit of area that is mainly used in agriculture to describe the area of fields.
Haber Process
An industrial process in which ammonia is manufactured by direct combination of its elements.
Hafnium
A silvery coloured, ductile metal which is found in all minerals containing zirconium.
Half Reactions
The two parts of an oxidation-reduction reaction, one representing oxidation, the other reduction.
Halide
A compound composed of two elements, one of which is a halogen (flourine, chlorine, bromine, iodine and astatine).
Halogen
Group of elements with similar bonding properties, consisting of flourine, chlorine, bromine, iodine and astatine.
Halon
Organic chemical compounds containing one or two carbon atoms, together with bromine and other halogens.
Hartree
The atomic unit of energy, named after the British physicist Douglas Hartree.
Hartshorn
Another name for Ammonium Bicarbonate.
Hazard
The potential that the use of a product will result in an adverse effect on a person or the environment.
HC
Abbreviation of Hydrocarbon.
HCL
Hydrochloric acid.
HCL
Hydrogen chloride.
HCN
Chemical formula for Hydrogen Cyanide.
HCP
Abbreviation of Hexagonal Close Packed, a crystal structure found for some metals.
He
Helium is an inert gaseous element.
Heat of Formation
The enthalpy change when 1 mole of a substance is formed from the elements in their standard states.
Heat Value
The heat developed by the combustion of one pound of fuel, Btu per Pound.
Heavy Metals
Metallic elements with high atomic weights can damage living things at low concentrations and tend to accumulate in the food chain.
Heavy Water

D2O

Water that contains 2H, rather than 1H. Heavy water is about 11% denser than ordinary water.

Helium
An inert gaseous element.
Helmholtz Free Energy
Energy released or absorbed in a reaction occurring reversibly at constant volume and temperature.
Hendecane
Another name for Undecane.
Hepatic Air
Old name for hydrogen sulphide.
Heptane

C7H16

An alkane hydrocarbon. A constituent of petroleum.

Hermetic
Sealing of an object so it is airtight.
Hess′s Law
In going from a particular set of reactants to a particular set of products, the enthalpy change is the same whether the reaction takes place in one step or a series of steps; in other words, enthalpy is a state function.
Heterocyclic Compounds
In chemistry, heterocyclic compounds are cyclic compounds in which the ring system of the molecule contains other elements than carbon.
Heterogeneous Catalysis
A form of catalysis in which the catalyst is in a different physical state than the reactants.
Heterogeneous Mixture
A sample of matter consisting of more than one pure substance and more than one phase.
Hexacarbonylmolybdenum
Alternative name for Molybdenum Hexacarbonyl.
Hexagonal Close Packed
A crystal structure found for some metals.
Hexane

C6H14

Hexane isomers are largely unreactive, and are frequently used as an inert solvent in organic reactions because they are very non-polar.

Hf
Hafnium is a silvery coloured, ductile metal which is found in all minerals containing zirconium.
HF
Chemical formula for Hydrofluoric Acid.
Hg
The most common liquid metal at room temperature.
Hg2Cl2
Chemical formula for Mercury I Chloride.
HgCl2
Chemical formula for Mercury II Chloride.
HgO
Chemical formula for Mercury II Oxide.
HgS
Mercuric Sulphide, the ore of mercury. Occuring as red crystals.
HI
Chemical formula for Hydrogen Iodide.
High Performance Liquid Chromatography
An efficient form of column chromatography that pumps a liquid solution of the sample at very high pressure through a column packed with a stationary phase made of very tiny particles.
High Spin Complex
A metal-ligand complex with the same number of unpaired electrons as the uncomplexed metal ion.
HNO3
Chemical formula for Nitric Acid.
Ho
Holmium is a member of the lanthanide group with properties closely resembling those of erbium and dysprosium.
Holmium
A member of the lanthanide group with properties closely resembling those of erbium and dysprosium.
Homogeneous
Having uniform properties or composition.
Homogeneous Catalysis
A form of catalysis in which the catalyst is in the same physical state as the reactants.
Homogeneous Mixture
A sample of matter consisting of more than one pure substance with properties that do not vary within the sample.
Homologous Series
A series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass.
Homopolymer
A polymer having a chain structure in which all mer units are of the same type.
HRb
Chemical formula for Rubidium Hydride.
Humectant
A substance that absorbs or retains moisture, added to a product to keep it from drying out.
Hunds Rule
When electrons are put into orbitals having the same energy, degenerate orbitals, one electron is put into each orbital before putting a second electron into an orbital.
Hybrid Orbitals
The combination of a set of atomic orbitals to produce a new set of hybrid orbitals.
Hydrargyrum
The old name for Mercury and from where the chemical symbol Hg was derived.
Hydrate
A compound that has discrete water molecules combined with it.
Hydrated Beryllia
Alternative name for Beryllium Hydroxide.
Hydration
The combination of water and another substance to produce a single product.
Hydration Number
The number of water molecules associated with an ion in the process of solvation in aqueous solutions.
Hydraulic Set Cement
A cement that sets through reaction with water.
Hydrazine

NH2NH2

A colourless, fuming, corrosive liquid that is a powerful reducing agent.

Hydride
A compound containing a negatively charged hydrogen.
Hydrocarbon
A chemical containing only hydrogen and carbon.
Hydrochloric Acid

HCl

A solution of hydrogen chloride in water. Concentrated acid is a colourless, fuming, corrosive liquid.

Hydrochloride
Alternative name for Hydrogen Chloride.
Hydrocyanic Acid
A solution of Hydrogen Cyanide in water.
Hydrofluoric Acid

HF

Aqueous solution of hydrogen fluoride. Dissolves most metals and etches glass.

Hydrogen
The least dense element. It has metallic and non-metallic properties.
Hydrogen Arsenide

AsH3

Intensely poisonous colourless gas. Also known as Arsine.

Hydrogen Bonding
Strong type of intermolecular dipole-dipole attraction. Occurs between hydrogen and fluorine, oxygen or nitrogen.
Hydrogen Carboxylic Acid
Another name for Methanoic Acid.
Hydrogen Chloride
Dissolves in water to produce hydrochloric acid.
Hydrogen Cyanide

HCN

Colorless, very poisonous and highly volatile liquid.

Hydrogen I Nitride
Modern name for Ammonia.
Hydrogen I Selenide

H2Se

Colourless gas.

Hydrogen I Telluride

H2Te

Colourless gas.

Hydrogen Iodide

HI

Colourless gas.

Hydrogen Peroxide

H2O2

A colourless, viscous, unstable liquid compound of hydrogen and water with oxidising and reducing properties. Used for bleaching wool, silk, linens, furs and hair products since the 19th century. During the Second World War hydrogen peroxide was used as a propellant in V1 rockets and was subsequently also used as a propellant for submarines. Hydrogen peroxide is also used as a preservative and disinfectant and is used by archaeologists to dissolve clay from finds.

Hydrogen Persulphide

H2S2

Colourless liquid.

Hydrogen Rich Fuel
A fuel that contains a significant amount of hydrogen.
Hydrogen Storage
There are types of hydrogen storage: compressed gas, liquid or chemical.
Hydrogen Sulphide
Poisonous and smells of rotten eggs.
Hydrogenation
A chemical reaction in which hydrogen is added to a compound.
Hydroiodic Acid
Alternative name for Hydrogen Iodide.
Hydrolysis
When water reacts with another substance and as a result the oxygen in water makes a bond with the substance.
Hydrophilic
A polar molecule or group that can form strong hydrogen bonds with water.
Hydrophobic
A nonpolar molecule or group that has little affinity for water.
Hydroquinone
A reducing agent used in photographic developers.

Hydrous
A substance that contains water. The opposite of anhydrous.
Hydroxide
The OH- ion or compounds containing the OH- ion.
Hydroxy Group
An -OH group attached to an organic molecule.
Hydroxybutanedioic Acid

C4H6O5

An organic dicarboxylic acid extracted from apples and various other fruits.

Hygroscopic
Able to absorb moisture from air.
Hypergolic Mixture
An oxidizing agent and a fuel that react or ignite instantly and spontaneously on contact.
Hypertonic
A solution which has higher osmotic pressure than some other solution.
I
Iodine is in the halogen group of elements.
Ice
Formed when water is cooled below its freezing point.

Ideal Solution
All molecules interact in exactly the same way; the solvent-solvent, solvent-solute, and solute-solute intermolecular forces are all equivalent.
Immiscible
Incapable of being mixed.
Impurities
Undesirable foreign material in a pure substance or mixture.
In
Indium is a soft, malleable and ductile metal which is generally unaffected by air or water but is soluble in acids.
In2O3
Chemical formula for Indium III Oxide.
In2S3
Chemical formula for Indium III Sulphide.
In2Se3
Chemical formula for Indium III Selenide.
In2Te3
Chemical formula for Indium III Telluride.
InAs
Chemical formula for Indium Arsenide.
InBr
Chemical formula for Indium I Bromide.
InBr3
Chemical formula for Indium III Bromide.
InCl3
Chemical formula for Indium III Chloride.
Inclusion
Foreign particle present as an undesirable impurity in a material.
Incomplete Combustion
A combustion reaction or process that does not convert all of the fuel′s carbon and hydrogen into carbon dioxide and water, respectively.
Incomplete Octet
An atom with less than eight electrons in its valence shell.
Indicator
A substance that undergoes a sharp, easily observable change when conditions in its solutions change.
Indicator Diagram
A plot of pressure vs. volume.
Indirect Titration
Determining the concentration of an analyte by reacting it with a known number of moles of excess reagent.
Indium
A soft, malleable and ductile metal which is generally unaffected by air or water but is soluble in acids.
Indium Antimonide

InSb

A narrow gap semiconductor material from the III-V group used in infrared detectors, including thermal imaging cameras, FLIR systems, infrared homing missile guidance systems, and in infrared astronomy.

Indium Arsenide

InAs

A semiconductor material that has the appearance of grey cubic crystals and is used for construction of infrared detectors.

Indium Gallium Aluminium Nitride

InGaAlN

Semiconductor that is the base for blue LEDs.

Indium Gallium Arsenide

InGaAs

Semiconductor used in high-power and high-frequency electronics because of its superior electron velocity with respect to the more common semiconductors silicon and gallium arsenide.

Indium Gallium Nitride
Semiconductor material made from a mix of Gallium Nitride and Indium Nitride.

Indium Gallium Phosphide

InGaP

Semiconductor composed of indium, gallium and phosphorus used in high-power and high-frequency electronics.

Indium I Bromide

InBr

A red crystalline compound made from heating the Indium metal with InBr3.

Indium III Bromide

InBr3

Hygroscopic yellow-white monoclinic crystals.

Indium III Chloride

InCl3

Colourless salt finds some use in organic synthesis as a Lewis acid and is also the most available soluble derivative of indium.

Indium III Fluoride

InF3

Used in the synthesis on non-oxide glasses.

Indium III Oxide

In2O3

Used as an n-type semiconductor and as a resistive element in integrated circuits.

Indium III Selenide

In2Se3

Potential for use in photovoltaic devices and it has been the subject of extensive research.

Indium III Sulphate

In2(SO4)3

White-grey odourless powder, hygroscopic.

Indium III Sulphide

In2S3

The first indium compound ever described.

Indium III Telluride

In2Te3

Forms blue cubic crystals.

Indium Monoarsenide
Alternative name for Indium Arsenide.
Indium Nitride

InN

Small bandgap semiconductor material which has potential application in solar cells and high speed electronics.

Indium Phosphide

InP

A binary semiconductor used in high-power and high-frequency electronics.

Indium Sesquiselenide
Alternative name for Indium III Selenide.
Indium Tin Oxide

ITO

Main feature is the combination of electrical conductivity and optical transparency.

Inductive Effect
An inductive effect is the polarization of a chemical bond caused by the polarization of an adjacent bond.
Inert
Something that lacks a chemical action.
Inert Gas
A gas which does not normally combine chemically with other elements.
Inert Pair
Valence electrons in an s orbital penetrate to the nucleus better than electrons in p orbitals, and as a result they′re more tightly bound to the nucleus and less able to participate in bond formation.
Inflammable
A substance which is easily set on fire.
Inflammable Air
An old name for Hydrogen.
Infra-Red Spectroscopy
A technique for determining the structure of molecules by observing how infrared radiation is absorbed by a sample.
InGaAlN
Chemical formula for Indium Gallium Aluminium Nitride.
InGaAs
Chemical formula for Indium Gallium Arsenide.
InGaP
Chemical formula for Indium Gallium Phosphide.
Inhibitor
An additive used to retard undesirable chemical action in a product.
Initiator
A compound required to start a chain reaction.
InN
Chemical formula for Indium Nitride.
Inorganic Material
Substances not derived from living things.
Inositol

C6H12O6

A carbohydrate, though not a classical sugar. It has a taste which has been assayed at half the sweetness of table sugar.

InP
Chemical formula for Indium Phosphide.
InSb
Chemical formula for Indium Antimonide.
Insoluble
Refers to a substance that does not dissolve in a solvent to any significant degree.
Intensive Properties
Properties which are independent of the amount of the substance.
Interdiffusion
Diffusion of atoms of one metal into another metal.
Intermediate Solid Solution
A solid solution or phase having a composition range that does not extend to either of the pure components of the system.
Intermediate Species
Species formed in a reaction consisting of more than one step.
Intermetallic
A compound of two metals that has a distinct chemical formula. The bonds in intermetallic compounds are often partly ionic.
Intermolecular Forces
Forces between molecules.
Internal Energy
A property of a system that can be changed by a flow of work, heat or both.
Interstitial Site
Octahedral and tetrahedral open spaces within a close-packed arrangement of atoms or ions in which a cation can fit.
Interstitial Solid Solution
A solid solution wherein relatively small solute atoms occupy interstitial positions between the solvent or host atoms.
Intramolecular Forces
Forces within molecules. Forces caused by the attraction and repulsion of charged particles.
Intumescent
A substance which swells as a result of heat exposure, thus increasing in volume, and decreasing in density.
Invar
An alloy of iron and nickel.

Iodine
In the halogen group of elements.
Iodine Number
The number of grams of iodine required to saturate 100 grams of fat.
Ion
An atom, or group of atoms, which has either gained or lost electrons.
Ion Dipole Forces
Intermolecular force that exist between charged particles and partially charged molecules.
Ion Exchange
An exchange of ions between two electrolytes or between an electrolyte solution and a complex.
Ion Exchange Resin
A method of separating ions from a solution by reversibly binding them onto a resin that has charged sites on its surface.
Ionic Bond
This describes the electrostatic attraction of two oppositely charged ions in a crystalline lattice.
Ionic Compound
A compound made of distinguishable cations and anions, held together by electrostatic forces.
Ionic Dissociation
When ionic substances dissolve, their ions are surrounded by solvent molecules and separated from each other.
Ionic Radius
The radii of anions and cations in crystalline ionic compounds, as determined by consistently partitioning the centre-to-centre distance of ions in those compounds.
Ionic Strength
A measure of strength of a solution based on both the concentrations and valences of the ions present.
Ionization Energy
Energy required to remove an electron from a specific atom.
Ionizing Radiation
A particle or a photon with enough energy to knock off an electron from an atom.
Ir
Iridium is a rare, precious metallic element which is hard, brittle and has a low ductility.
IrF4
Chemical formula for Iridium IV Fluoride.
IrF5
Chemical formula for Iridium V Fluoride.
IrF6
Chemical formula for Iridium VI Fluoride.
Iridium
A rare, precious metallic element which is hard, brittle and has a low ductility.
Iridium Hexafluoride
Alternative name for Iridium VI Fluoride.
Iridium IV Fluoride

IrF4

Dark brown solid.

Iridium IV Oxide

IrO2

The only well characterised oxide of iridium.

Iridium Pentafluoride
Alternative name for Iridium V Fluoride.
Iridium Tetrafluoride
Alternative name for Iridium IV Fluoride.
Iridium V Fluoride

IrF5

A highly reactive yellow low melting solid.

Iridium VI Fluoride

IrF6

A volatile and highly reactive yellow solid, with an octahedral molecular structure.

Iridosmine
Iridosmine (osmiridium) is a naturally occurring alloy of osmium and iridium.
IrO2
Chemical formula for Iridium IV Oxide.
Iron
One of the most abundant metallic elements (41000 ppm) and probably one of the most important, being used on the largest scale of any metal.
Iron Hydroxide

FeO(OH)

Found as the minerals Siderogel and Feroxyhyte. It also has a variant known as Lepidocrocite.

Iron II Chloride

FeCl2

Pale yellow to white crystalline solid.

Iron II Hydroxide

Fe(OH)2

Green colour.

Iron II Oxide

FeO

Black colour powder. The powder in particular can cause explosions as it readily ignites.

Iron II Sulphate

FeSO4

Also known as the mineral Melanterite or Copperas. Green Vitriol is hydrated Iron II Sulphate.

Iron II Sulphide

FeS2

A brassy yellow colour. Also known as pyrite, iron pyrites and fools gold.

Iron III Chloride

FeCl3

Brown black or green crystalline solid.

Iron III Oxide

Fe2O3

Known in its natural state as Haematite, but also purified for use as a coating in magnetic audio and computer media, where it is known as Ferric oxide.

Iron Pyrites
Old name for Iron II Sulphide.
Iron Sulphide

FeS

White crystalline solid.

Isoelectric
Refers to a group of atoms or ions having the same number of electrons.
Isoleucine

C6H13NO2

A naturally occuring amino acid with a nonpolar side chain.

Isomer
Molecules with identical molecular formulas but different structural formulas.
Isomerism
The phenomenon whereby two or more polymer molecules or mer units have the same composition but different structural arrangements and properties.
Isomerization
A chemical change that involves a rearrangement of atoms and bonds within a molecule, without changing the molecular formula.
Isopropyl Alcohol
The IUPAC name for Propanol.
Isosteric
Having identical valence electron configurations.
Isotactic
A type of polymer chain configuration wherein all side groups are positioned on the same side of the chain molecule.
Isotone
One of a group of atoms or ions with nuclei that contain the same number of neutrons but different numbers of protons.
Isotonic
Refers to solutions that have equal osmotic pressure.
Isotopes
Two atoms having the same number of protons but different numbers of neutrons are said to be isotopes of each other.
Isotopic Abundance
The fraction of atoms of a given isotope in a sample of an element.
Isotopic Mass
The mass of a single atom of a given isotope, usually given in daltons.
Isotropic
Having identical values of a property in all crystallographic directions
ITO
Chemical formula for Indium Tin Oxide.
K
Potassium is a soft, silvery coloured metal, which like other members of the alkali group of metals, is extremely reactive.
K2O
Chemical formula for Potassium Oxide.
K2O2
Chemical formula for Potassium Peroxide.
K2S
Chemical formula for Potassium Sulphide.
Kalium
The old name for Potassium and from where the chemical symbol K was derived.
Kapok
Used as an insulating or flotation material it comes from the seed hairs of the kapok tree (Ceiba Pentranda).
KBr
Chemical formula for Potassium Bromide.
KC2H3O2
Chemical formula for Potassium Acetate.
KCl
Chemical formula for Potassium Chloride.
Keir Metal
Brass containing 55% copper, 40% zinc and 5% iron. Patented in 1779 by James Keir (Chemist, Geologist, Industrialist and Inventor) and used for the manufacture of window frames.

Ketone
Compunds containing a carbonyl group (-CO-) attached to two hydrocarbon radicals. The simplest ketone is acetone (CH3COCH3).
KF
Chemical formula for Potassium Fluoride.
KI
Chemical formula for Potassium Iodide.
Kiln
A furnace in which ceramics are fired.
Kinetic Molecular Theory
This theory assumes that molecules must collide in order to react. The more collisions the more likely it is for a reaction to occur.
Kinetics
The study of how fast reactions occur.
kJ
An abbreviation of kilojoule, one thousand joules. The SI unit of energy is the joule.
KMnO4
Potassium Manganate VII
KNO3
Chemical formula for Potassium Nitrate.
KO2
Chemical formula for Potassium Superoxide.
KOH
Potassium Hydroxide.
Kr
Krypton is a rare gaseous element.
Krypton
A rare gaseous element.
La
Lanthanum is a soft, ductile, white metallic element which oxidises rapidly in air.
La2O3
Chemical formula for Lanthanum III Oxide.
LaB6
Chemical formula for Lanthanum Hexaboride.
LaBr3
Chemical formula for Lanthanum III Bromide.
LaC2
Chemical formula for Lanthanum Carbide.
LaCl3
Chemical formula for Lanthanum III Chloride.
Lacquer
A fast-drying usually clear coating that is highly flammable and dries by solvent evaporation only.
Lactic Acid

C3H6O3

Plays a role in various biochemical processes.

Langasite
Alternative name for Lanthanum Gallium Silicate.
Lanthana
Alternative name for Lanthanum III Oxide.
Lanthanide
Elements 57-70 are called lanthanides.
Lanthanide Contraction
An effect that causes sixth period elements with filled 4f subshells to be smaller than otherwise expected.
Lanthanum
A soft, ductile, white metallic element which oxidises rapidly in air.
Lanthanum Carbide

LaC2

Used it to study the manufacture of certain types of superconductors and nanotubes.

Lanthanum Carbonate

La2(CO3)3

An ore of lanthanum metal, along with monazite.

Lanthanum Gallium Silicate
A piezoelectric material, with no phase transitions up to its melting point of 1470 °C.

Lanthanum Hexaboride

LaB6

Used in hot cathodes, either as a single crystal or as a coating deposited by physical vapor deposition.

Lanthanum III Bromide

LaBr3

A colourless white powder used as a source of lanthanum in chemical synthesis.

Lanthanum III Chloride

LaCl3

Used as a mild Lewis acid to perform chemical reactions that usually require acidic conditions, such as converting aldehydes to acetals, under nearly neutral conditions.

Lanthanum III Oxide

La2O3

Used at a laboratory level to develop ferroelectric and in optical materials.

Lanthanum Sesquioxide
Alternative name for Lanthanum III Oxide.
Lanthanum Strontium Cobalt Ferrite
Being investigated as a material for intermediate temperature solid oxide fuel cell cathodes and as a membrane material for separation of oxygen from air.

Lanthanum Strontium Manganite
Commonly used in as a cathode material in commercially produced solid oxide fuel cells.

Lanthanum Trichloride
Alternative name for Lanthanum III Chloride.
Lard Oil
An oil made from animal fats usually mixed with mineral oils to reduce its cost and improve its qualities. Used in engineering as a cutting oil.

Lattice
An orderly arrangement of atoms in a material.
Lattice Parameter
The combination of unit cell edge lengths and interaxial angles that defines the unit cell geometry.
Laughing Gas
Nitrous oxide, an anaesthetic.
Law of Combining Volumes
When gases react, they do so in a definite proportion by volume, if the volumes are measured at the same pressure and temperature.
Law of Conservation of Mass
There is no change in total mass during a chemical change.
Law of Definite Proportions
When two pure substances react to form a compound, they do so in a definite proportion by mass.
Law of Multiple Proportions
When one element can combine with another to form more than one compound, the mass ratios of the elements in the compounds are simple whole-number ratios of each other.
Lawrencium
The only known isotope has a half life of 8 seconds.
Le Chatelier′s Principle
Predicts that when a stress is applied to an equilibrium mixture, the equilibrium will shift to relieve the stress.
Lead
A soft, malleable and ductile metallic element that has been known of and used since prehistoric times.
Lead II Acetate

Pb(C2H3O2)2

Used as a reagent to make other lead compounds and as a fixative for some dyes.

Lead II Carbonate

PbCO3

Decomposes readily into Lead II Oxide and carbon dioxide at 200°C and can be reduced to lead using carbon monoxide.

Lead II Chromate IV

PbCrO4

Used as a pigment due to the strong yellow colour.

Lead II Oxide

PbO

Lead monoxide varies in colour from pale yellow to brown, used in the manufacture of glass, paints, varnishes and glazes.

Lead II Sulphide

PbS

Grey crystalline solid.

Lead IV Oxide

PbO2

Lead dioxide a dark brown powder, strong oxidizing agent.

Lead Tetraethyl
Alternative name for Tetraethyl Lead.
Lean Burn
A fuel air mixture that contains higher amounts of air than normally used.
Leclanché Cell
A electrolytic cell also known as a dry cell that uses a moist paste rather than a liquid as an electrolyte.
Lepidocrocite
Alternative name for Iron Hydroxide.
Leucine

(CH3)2CHCH2CH(NH2)COOH

A naturally occuring aliphatic amino acid with a nonpolar side chain.

Lever Rule
Mathematical expression whereby the relative phase amounts in a two-phase alloy at equilibrium may be computed.
Levorotatory
A chiral molecule which rotates plane-polarized light to the left.
Lewis Structure
A model pioneered by Gilbert N. Lewis and Irving Langmuir that represents the electronic structure of a molecule by writing the valence electrons of atoms as dots.
LH2
Abbreviation for Liquefied Hydrogen.
Li
Lithium is a soft, silver metal, and is the first member of the alkali group of metals.
Li2NH
Chemical formula for Lithium Imide.
Li2
Chemical formula for Lithium I Oxide.
Li2O2
Chemical formula for Lithium I Peroxide.
Li3N
Chemical formula for Lithium I Nitride.
LiBr
Chemical formula for Lithium I Bromide.
LiCl
Chemical formula for Lithium I Chloride.
LiF
Chemical formula for Lithium I Fluoride.
Ligand
A molecule or ion that binds to a metal cation to form a complex.
Lignite
A type of coal with lowest carbon content (25% to 35%) and a low heat value called "brown coal", used mainly for electric power generation.

LiH
Chemical formula for Lithium I Hydride.
LiI
Chemical formula for Lithium I Iodide.
Limescale
Hard, off-white, chalky deposit found in kettles, hot-water boilers and the inside of inadequately maintained hot-water central heating systems.
Limestone
Naturally occuring Calcium Carbonate.
Limiting Reagent
The reactant that will be exhausted first.
Linseed Oil
Obtained from the seeds flax. Originally used in the production of paints.
LiO2
Chemical formula for Lithium Superoxide.
Lipid
A diverse group of organic molecules that contain long hydrocarbon chains or rings and are hydrophobic.
Lipophilic
Refers to a substance′s solubility in fat.
Lipowitz Alloy
A low melting point alloy used to form shields in radiotherapy.

Liquefied Hydrogen
Hydrogen in liquid form.
Liquefied Natural Gas
Natural gas that has been refrigerated to cryonic temperatures where the gas condenses into a liquid.
Liquefied Petroleum Gas
A flammable mixture of hydrocarbon gases used as a fuel, primarily mixes of propane, butane or both.
Liquid
Matter with a definite volume that takes the shape of its container.
Liquid Desiccant
A hygroscopic liquid, such as glycol, used to remove water from other fluids.
Liquid Organic Hydrogen Carriers
These are liquid pumpable, easily rechargeable and have acceptable gravimetric storage densities, similar volumetric storage densities to cryogenic liquid hydrogen.
Litharge
Lead monoxide varies in colour from pale yellow to brown, used in the manufacture of glass, paints, varnishes and glazes.
Lithium
A soft, silver metal, and is the first member of the alkali group of metals.
Lithium I Bromide

LiBr

White crystalline solid.

Lithium I Chloride

LiCl

White crystalline solid.

Lithium I Fluoride

LiF

White crystalline solid.

Lithium I Hydride

LiH

White to grey crystalline solid.

Lithium I Iodide

LiI

White crystalline solid.

Lithium I Nitride

Li3N

Purple or red crystalline solid.

Lithium I Oxide

Li2O

White crystalline solid.

Lithium I Peroxide

Li2O2

White crystalline solid.

Lithium Imide

Li2NH

A white solid that turns brick red in sunshine.

Lithium Superoxide

LiO2

Yellow crystalline solid.

Litmus
A mixture of pigments extracted from certain lichens that turns blue in basic solution and red in acidic solution.
Litmus Paper
Paper impregnated with litmus, usually cut in narrow strips.
Lixivial Salts
Salts prepared by lixiviations.
Lixiviation
Separation of soluble from unsoluble solid substances by soaking the mixture of solids and removing the resulting solution which contained the soluble material.
Lixivium
A solution produced by lixiviation. Sometimes used as a general synonym for "Solution".
LNG
Abbreviation of Liquefied Natural Gas.
Lock and Key Model
A model that explains the role of enzymes in chemical reactions by assuming that the reactants fit into the enzyme like a key fits into a lock.
LOHC
Abbreviation of Liquid Organic Hydrogen Carriers.
London Force
An intermolecular attractive force that arises from a cooperative oscillation of electron clouds on a collection of molecules at close range.
Lone Pair
Electrons that are not involved in bonding.
Low Spin Complex
A metal-ligand complex with fewer unpaired electrons than the uncomplexed metal ion.
lox
Liquid oxygen.
LPG
Abbreviation of Liquefied Petroleum Gas.
Lr
The only known isotope of lawrencium has a half life of 8 seconds.
Lu
Lutetium is the hardest, densest and one of the rarest of the lanthanide group of elements.
Lu2O3
Chemical formula for Lutetium III Oxide.
Lucite
Tradename for Polymethyl Methacrylate Resin.
LuCl3
Chemical formula for Lutetium III Chloride.
Lunar Crystals
Old name for Silver Nitrate.
Lutetium
The hardest, densest and one of the rarest of the lanthanide group of elements.
Lutetium Aluminium Garnet

Al5Lu3O12

A ceramic material that has been proposed for use as a high refractive index lens material.

Lutetium III Chloride

LuCl3

Forms hygroscopic white monoclinic crystals that heated with calcium forms pure lutetium metal.

Lutetium III Oxide

Lu2O3

An important raw material for laser crystals and has specialized uses in ceramics, glass and phosphors.

Lutetium Tantalate

LuTaO4

The densest known white stable material.

Lutetium Trichloride
Alternative name for Lutetium III Chloride.
Lye
Alternative name for Sodium Hydroxide.
Lys
Abbreviation of Lysine.
Lysine

HO2CCH(NH2)(CH2)4NH2

A naturally occurring amino acid with an amine group on its side chain.

Macromolecule
A huge molecule made up of thousands of atoms
Macroscopic
Anything big enough to be seen with the naked eye.
Macrostate
A time-average of many microstates; this is a state of the system that can actually be observed.
Madelung Constant
A constant representing the sum of the mutual potential coulombic attractive energy of all the ions in a lattice in the equation for the energy of an ionic crystal.
Magnalium
An alloy of magnesium and aluminium used in aircraft manufacture.

Magnesium
A brilliant white metal, which is relatively soft and is one of the more abundant elements in the earth’s crust.
Magnesium Aspartate

C8H12MgN2O8

The magnesium salt of aspartic acid, is a mineral supplement.

Magnesium Benzoate

C14H10MgO4

A chemical compound formed from magnesium and benzoic acid. It was once used to treat gout and arthritis.

Magnesium Bromide

MgBr2

Often used as a mild sedative and as an anticonvulsant for treatment of nervous disorders.

Magnesium Carbonate

MgCO3

White solid that occurs in nature as a mineral.

Magnesium Chloride

MgCl2

The principal precursor to magnesium metal, which is produced on a large scale.

Magnesium Citrate

C6H6O7Mg

Used medicinally as a saline laxative and to empty the bowel prior to a surgery.

Magnesium Diboride

MgB2

An inexpensive and useful superconducting material.

Magnesium Dichloride
Alternative name for Magnesium Chloride.
Magnesium Diglutamate

MgC10H16N2O8

Magnesium acid salt of glutamic acid.

Magnesium Diuranate

MgU2O7

Forms the major part of some yellowcake mixtures that are an intermediate product in the uranium refining process.

Magnesium Fluoride
Used as antireflection coating for lenses because of its low refractive index.

Magnesium Gluconate

MgC12H22O14

Magnesium salt of gluconic acid.

Magnesium Hydride

MgH2

Has been studied as a potential hydrogen storage medium.

Magnesium Hydroxide

Mg(OH)2

As a suspension in water, it is often called milk of magnesia because of its milk-like appearance and is used to neutralize stomach acid and as a laxative.

Magnesium Iodide

MgI2

Few commercial uses but can be used to prepare compounds for organic synthesis.

Magnesium Nitrate

Mg(NO3)2

Hygroscopic salt that in air quickly forms the hexahydrate.

Magnesium Nitride

Mg3N2

Reacts with water to produce ammonia gas.

Magnesium Orotate

C10H6MgN4O8

The magnesium salt of orotic acid which is a mineral supplement.

Magnesium Oxide
Formed by igniting Magnesium in air.
Magnesium Perchlorate

Mg(ClO4)2

Powerful oxidizing agent that is highly exothermic with addition of water.

Magnesium Peroxide

MgO2

Releases oxygen by breaking down at a controlled rate with a hydrous fluid.

Magnesium Salt
Alternative name for Magnesium Stearate.
Magnesium Silicide

Mg2Si

Used to create aluminium alloys of the 6xxx group, containing up to approximately 1.5% Mg2Si.

Magnesium Stearate

C36H70MgO4

Widely regarded as harmless, it is often used as a diluent in the manufacture of medical tablets.

Magnesium Sulphate

MgSO4

Traditionally used as a component of bath salts.

Magnesium Sulphide

MgS

Wide band-gap direct semiconductor of interest as a blue-green emitter.

Magnesium Sulphite

MgSO3

Readily absorbs water from the air.

Magnesium Trisilicate

Mg2O8Si3

A food additive that is used as a kind of absorbent to filter unwanted residue fat from used frying oil.

Magnox
Magnesium with small amounts of aluminium and other metals—used in cladding unenriched uranium metal fuel with a non-oxidising covering to contain fission products.

Malic Acid
Another name for Hydroxybutanedioic Acid.
Manganese
A hard, brittle, silvery coloured, metallic element which resembles iron in being moderately reactive and dissolving in cold, dilute non-oxidising acids.
Manganese Bronze
A copper alloy containing zinc, manganese and a small quantity of nickel.

Manganese Carbonate

MnCO3

Widely used as an additive to plant fertilizers to cure manganese deficient crops. Also used in health foods, ceramic glaze colorant and flux, and in concrete stains.

Manganese Diacetate
Alternative name for Manganese II Acetate.
Manganese II Acetate

Mn(CH3COO)2

Used as a desiccant, a catalyst, and as fertilizer.

Manganese IV Oxide

MnO2

This blackish or brown solid occurs naturally as the mineral pyrolusite.

Manganese VII Oxide

Mn2O7

Volatile liquid is highly reactive and more often discussed than observed or intentionally prepared.

Manganic Oxide
Alternative name for Manganese VII Oxide.
Manganin
Alloy with 84% copper, 12% manganese and 4% nickel used in wire form for making heating elements.

Mannitol

C6H14O6

Originally isolated from the secretions of the flowering ash and called manna after its resemblance to the Biblical food.

Marble
A granular metamorphosed limestone that is often polished and used for decoration.
Marsh Gas
The natural occurence of methane.
Mass Action Law
The law which describes the relation between the densities of species involved in a chemical reaction.
Mass Percentage
Mass percentages express the concentration of a component in a mixture or an element in a compound.
Mass Spectrometer
An instrument for producing ions in a gas and determining their mass and hence composition.
Mass Spectrum
A plot showing the results of a mass spectrometry experiment, which shows the presence of particles with different masses as a series of sharp, separate peaks.
Massicot
Mineral form of Lead II Oxide.
Material Safety Data Sheet
Safety information sheet for a particular substance that lists physical properties, hazards, cleanup and disposal procedures, fire and explosion data, and protective equipment required.
Materials
Lists all Materials topics in the Encyclopaedia
Md
Mendelevium is a man-made element with an atomic number of 101.
Measurement
The collection of quantitative data.
Melanterite
The mineral name for Iron II Sulphate.
Melting Point
The temperature at which a solid substance changes to a liquid state.
Mendelevium
Man-made element with an atomic number of 101.
Menthol

C10H20O

A waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above.

Mer
The group of atoms that constitutes a polymer chain repeat unit.
Mercuric Chloride
Another name for Mercury II Chloride.
Mercuric Oxide
Another name for Mercury II Oxide.
Mercuric Sulphide

HgS

The ore of mercury. Occuring as red crystals.

Mercurous Chloride
Another name for Mercury I Chloride.
Mercury Dichlorate
Another name for Mercury II Chloride.
Mercury Hg
The most common liquid metal at room temperature.
Mercury I Chloride

Hg2Cl2

Dense white or yellowish-white odorless solid. It was used in medicine as a diuretic and laxative although this is now discontinued.

Mercury II Chloride

HgCl2

One of the most toxic forms of Mercury.

Mercury II Oxide

HgO

A red or orange solid at room temperature that is used in the production of Mercury as it decomposes readily.

Meso Compound
A compound that has two or more chiral centres but does not rotate plane-polarized light because it has an internal plane of symmetry.
Mesomeric Effect
Another name for Resonance Effect.
Metabolite
A compound produced by metabolic reactions.
Metal
A metal is a substance that conducts heat and electricity, is shiny and reflects many colors of light, and can be hammered into sheets or drawn into wire.
Metal Alloy
Metal blended with some other metallic or non-metallic substance to give it special qualities.
Metallic Bond
A primary interatomic bond involving the nondirectional sharing of nonlocalized valence electrons which are mutually shared by all the atoms in the metallic solid.
Metallic Compound
Compound that contains at least one metallic element.
Metallic Radius
The atomic radius from as established by measuring the distances between atoms in metallic crystals.
Metallurgy
The science and technology of metals and alloys.
Methanal
Alternative name for Formaldehyde.
Methane
The first alkane. Occurs naturally as marsh gas and in oil wells.
Methane Trichloride
Alternative name for Chloroform.
Methanoic Acid

CH2O2

Most famous for it's occurrence in Ant and Bee venom.

Methanol
A colourless liquid also known as methyl alcohol.
Methenyl Trichloride
Alternative name for Chloroform.
Methoxymethane
Alternative name for Dimethyl Ether.
Methyl
The monovalent radical -CH3
Methyl Acetate

C3H6O2

A clear, flammable liquid with a characteristic, not unpleasant smell like certain glues or nail polish removers.

Methyl Alcohol
Also known as methanol.
Methyl Bromide
Alternative name for Bromomethane.
Methyl Chloride
Alternative name for Chloromethane.
Methyl Cyanide
Also known as Acetonitrile.
Methyl Ethanoate
Alternative name for Methyl Acetate.
Methyl Ether
Alternative name for Dimethyl Ether.
Methyl Phenyl Ether
Also known as Anisole.
Methyl Tertiary Butyl Ether
A fuel oxygenate used as an additive to gasoline to increase octane and reduce engine knock.

Methyl Trichloride
Alternative name for Chloroform.
Methylbenzene
Also known as toluene.
Methylene Chloride
Alternative name for Dichloromethane.
Methylene Dichloride
Alternative name for Dichloromethane.
Metrology
The science of dimensional measurement; sometimes includes the science of weighing.
Mg
A brilliant white metal, which is relatively soft and is one of the more abundant elements in the earth’s crust.
Mg2O8Si3
Chemical formula for Magnesium Trisilicate.
Mg2Si
Chemical formula for Magnesium Silicide.
Mg3N2
Chemical formula for Magnesium Nitride.
MgB2
Chemical formula for Magnesium Diboride.
MgBr2
Chemical formula for Magnesium Bromide.
MgC10H16N2O8
Chemical formula for Magnesium Diglutamate.
MgC12H22O14
Chemical formula for Magnesium Gluconate.
MgCl2
Chemical formula for Magnesium Chloride.
MgCO3
Chemical formula for Magnesium Carbonate.
MgF2
Formula for Magnesium Fluoride.
MgH2
Chemical formula for Magnesium Hydride.
MgI2
Chemical formula for Magnesium Iodide.
MgO
Chemical formula for Magnesium Oxide.
MgO2
Chemical formula for Magnesium Peroxide.
MgS
Chemical formula for Magnesium Sulphide.
MgSO3
Chemical formula for Magnesium Sulphite.
MgSO4
Chemical formula for Magnesium Sulphate.
MgU2O7
Chemical formula for Magnesium Diuranate.
Mica
A group of silicates with similar chemical composition. Used as an electrical insulator.
Microscopic
Refers to objects that are too small for the unaided eye to see.
Microscopy
The investigation of microstructural elements using some type of microscope.
Microstate
Each arrangement of the ensemble; every possible arrangement of the atoms or molecules in the system.
Milk
Opaque white liquid secreted by female mammals for feeding young.
Milk Acid
Another name for Lactic Acid.
Milk of Magnesia
Alternative name for Magnesium Hydroxide.
Miller Indices
A set of three integers that designate crystallographic planes, as determined from reciprocals of fractional axial intercepts.
Miller-Bravis Indices
A set of four integers that designate crystallographic planes in hexagonal crystals.
Mineral
A naturally occurring inorganic substance having specified chemical composition and crystalline structure.
Mineral Oil
A liquid by-product of the distillation of petroleum to produce gasoline and other petroleum based products from crude oil.
Mineral Wool
Also known as rock wool.
Mischmetal
An alloy of cerium, rare-earth metals and iron.

Miscible
Two liquids are considered "miscible" or mixable if shaking them together results in a single liquid phase, with no meniscus visible between layers of liquid.
Mixed Dislocation
A dislocation that has both edge and screw components.
Mixed Glyceride
A diglyceride or triglyceride that contains more than one type of fatty acid connected to glycerol via an ester linkage.
Mixture
Two or more substances which are not chemically bonded together.
Mn
Manganese is a hard, brittle, silvery coloured, metallic element which resembles iron in being moderately reactive and dissolving in cold, dilute non-oxidising acids.
Mn2O7
Chemical formula for Manganese VII Oxide.
MNCO3
Chemical formula for Manganese Carbonate.
Mo
Molybdenum is a lustrous, silvery coloured metal that resembles tungsten with which it tends to be paired in the transition series in the periodic table.
MoCl2
Chemical formula for Molybdenum II Chloride.
MoCl4
Chemical formula for Molybdenum IV Chloride.
MoF6
Chemical formula for Molybdenum Hexafluoride.
mol
Abbreviation of Mole, the SI unit of Amount of Substance.
Molality
Concentration measured as moles of solute per kilogram of solvent.
Molar
Pertaining to moles or a synonym for molarity.
Molar Gas Constant
R = 8.31441 JK-1mol-1
Molar Heat Capacity
The amount of heat required to raise the temperature of 1mol of a substance through 1K.
Molar Heat of Combustion
The amount of energy released in burning completely one mole of substance.
Molar Mass
The mass of one mole of a material.
Molar Volume
The volume occupied by one mole of a substance under specified conditions.
Molarity
Concentration of a solution measured as the number of moles of solute per litre of solution.
Mole
The SI unit of the Amount of Substance. It is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12.
Mole Fraction
The number of moles of a particular substance expressed as a fraction of the total number of moles.
Molecular Equation
A molecular equation is a balanced chemical equation in which ionic compounds are written as neutral formulas rather than as ions.
Molecular Formula
Shows the number of atoms of each element present in a molecule.
Molecular Geometry
Shape of a molecule, based on the relative positions of the atoms.
Molecular Orbital
A wavefunction that describes the behaviour of an electron in a molecule.
Molecular Sieve
A material that contains many small cavities interconnected with pores of precisely uniform size.
Molecular Slip
The existence of a finite net gas velocity at the surface of very small particles resulting in a lower drag force.
Molecular Weight
The combined weight (as given on the periodic table) of all the elements in a compound.
Molecularity of a Reaction
The number of species forming the transition state.
Molecule
The smallest part of an element or of a covalently bonded compound that can exist independently and still retain the ordinary chemical properties of that element or compound.
Molybdate
A compound containing an oxoanion with molybdenum in its highest oxidation state of 6.
Molybdenum
A lustrous, silvery coloured metal that resembles tungsten with which it tends to be paired in the transition series in the periodic table.
Molybdenum Dichloride
Alternative name for Molybdenum II Chloride.
Molybdenum Dioxide
Alternative name for Molybdenum IV Oxide.
Molybdenum Disilicide

MoSi2

A refractory ceramic with primary use in heating elements.

Molybdenum Disulphide

MoS2

The appearance and feel of molybdenum disulphide is similar to graphite. As per graphite, it is widely used as a solid lubricant because of its low friction properties, sometimes to relatively high temperatures.

Molybdenum Hexacarbonyl

C6O6Mo

A colourless solid noteworthy as a volatile, air-stable derivative of a metal in its zero oxidation state. Used in electron beam-induced deposition techniques.

Molybdenum Hexafluoride

MoF6

A solid which melts just below room temperature and hydrolyses in water to give hydrofluoric acid.

Molybdenum II Chloride

MoCl2

Attracts attention from researchers because of the unexpected structures seen for these compounds and the fact that they give rise to hundreds of derivatives.

Molybdenum IV Chloride

MoCl4

Black solid inorganic compound.

Molybdenum IV Oxide

MoO2

Violet coloured solid that is a metallic conductor.

Molybdenum Pentachloride
Alternative name for Molybdenum V Chloride.
Molybdenum Tetrachloride
Alternative name for Molybdenum IV Chloride.
Molybdenum Trioxide

MoO3

Used as an oxidation catalyst and as a raw material for the production of molybdenum metal.

Molybdenum V Chloride

Cl10Mo2

Dark volatile solid is an important starting reagent in the preparation of molybdenum compounds.

Molybdic Anhydride
Alternative name for Molybdenum Trioxide.
Monatomic Ion
An ion formed from a single atom by the loss or gain of electrons.
Monobromomethane
Alternative name for Bromomethane.
Monochloroethane
Alternative name for Chloroethane.
Monodentate
A ligand that has only one atom that coordinates directly to the central atom in a complex.
Monogermane
Alternative name for Germane.
Monomer
A molecule that, under the correct conditions, can link together with others to form larger molecules called polymers.
Monosilane
Alternative name for Silane.
Monosodium Glutamate

C5H8NNaO4

A sodium salt of glutamic acid, a naturally occurring non-essential amino acid.

Montroydite
Another name for Mercury II Oxide.
MoO2
Chemical formula for Molybdenum IV Oxide.
MoO3
Chemical formula for Molybdenum Trioxide.
MoS2
Chemical formula for Molybdenum Disulphide.
MoSi2
Chemical formula for Molybdenum Disilicide.
Mossbauer Spectrometer
An instrument that provides information on the bonding of an atom in a mineral by bombarding it with gamma rays.
Mother Liquor
The solution in recrystallization.
MSDS
Abbreviation of Material Safety Data Sheet.
MSG
Abbreviation of Monosodium Glutamate.
Multiple Bond
Sharing of more than one electron pair between bonded atoms.
Mumetal
An alloy of high magnetic permeability containing up to 78% nickel with iron, copper and manganese.
Muntz Metal
Stonger than normal brass and used for castings and hot worked items. 60 % Copper 40 % Zinc

Mustard Gas
Common name for Dichlorodiethyl Sulphide a gas used in warfare.
N
A gaseous colourless and odourless element that makes up about 80% of the atmosphere.
N2O
Chemical formula for Nitrous Oxide.
N4Si3
Chemical formula for Silicon Nitride.
Na
Sodium is a soft, silvery coloured metal which, like other members of the alkali group of metals, is extremely reactive.
Na2O
Chemical formula for Sodium Oxide.
Na2O2
Chemical formula for Sodium Peroxide.
NaBr
Chemical formula for Sodium I Bromide.
NaF
Chemical formula for Sodium I Fluoride.
Nafion

C7HF13O5S . C2F4

A sulfonated tetrafluoroethylene based fluoropolymer-copolymer.

NaH
Chemical formula for Sodium Hydride.
NaI
Chemical formula for Sodium I Iodide.
NaNO3
Chemical formula for Sodium Nitrate.
NaO2
Chemical formula for Sodium I Oxide.
NaO3Si
Chemical formula for Sodium Silicate.
NaOCl
Chemical formula for Sodium Hypochlorite.
NaOH
Chemical formula for Sodium Hydroxide.
Naphtha
Volatile solvent distilled from petroleum.
Naphthyleneethylene
Another name for Acenaphthene.
Natrium
Latin for sodium, hence the symbol Na.
Natural Abundance
The average fraction of atoms of a given isotope of an element on Earth.
Natural Gas
The cleanest fossil fuel, and hence a potential short-term aid to slowing climate change.
Natural Gas Distribution System
This term generally applies to mains, services, and equipment that carry or control the supply of natural gas from a point of local supply, up to and including the sales meter.
Nb
Niobium is a metallic element that is very reactive and forms an extremely stable oxide when exposed to air which enhances its corrosion resistance.
Nd
Neodymium is one of the more reactive members of the lanthanide group.
Nd2Fe14B
Chemical formula for Neodymium Iron Boron.
Nd2O3
Chemical formula for Neodymium III Oxide.
NdFeB
Abbreviation of Neodymium Iron Boron.
Ne
Neon is a light gaseous inert element.
Neodymium
One of the more reactive members of the lanthanide group.
Neodymium Aluminium Borate

NdAl3(BO3)4

Used in optics.

Neodymium III Oxide

Nd2O3

Used to dope glass, including sunglasses, make solid-state lasers, and to color glasses and enamels. It forms hygroscopic blue hexagonal crystals.

Neodymium Iron Boron

Nd2Fe14B

A type of rare-earth permanent magent which is an alloy of neodynium, iron and boron that forms a tetragonal crystalline structure.

Neodymium Sesquioxide
Alternative name for Neodymium III Oxide.
Neon
Light gaseous inert element.
Neptunium
Produced artificially by nuclear reaction between uranium and neutrons.
Net Chemical Reaction
A reaction that actually occurs as several elementary steps.
Network Covalent Solid
A substance which consists of an array of atoms held together by an array of covalent bonds.
Network Polymer
A polymer composed of trifunctional mer units that form three-dimensional molecules.
Neutral Ammonium Fluoride
Alternative name for Ammonium Fluoride.
Neutral Solution
An aqueous solution in which the concentrations of aqueous hydrogen ions and hydroxide ions are equal.
Neutralization Reaction
A chemical change in which one compound aquires H+ from another.
Neutron Activation Analysis
An extremely sensitive technique for analyzing trace amounts of elements in a sample.
Newtonian Fluid
A fluid whose viscosity does not depend on gradients in flow speed.
Newtons Alloy
A low melting point alloy.

NH2CH2COOH
Chemical formula for Glycine.
NH2CONH2
Chemical formula for Carboxamide or more commonly known as Urea.
NH2NH2
Chemical formula for Hydrazine.
NH3
Chemical formula for Ammonia.
NH4Cl
Chemical formula for Ammonium Chloride.
NH4F
Chemical formula for Ammonium Fluoride.
NH4HCO3
Chemical formula for Ammonium Bicarbonate.
NH4I
Chemical formula for Ammonium Iodide.
NH4NH4CO3
Chemical formula for Ammonium Carbonate.
NH4NO3
Chemical formula for Ammonium Nitrate.
NH4OH
Chemical formula for Ammonium Hydroxide.
Ni
Nickel is a metallic element that is malleable and ductile, and is resistant to corrosion in air or water, and hence is used as a protective coating.
Niacin
Vitamin B3 is a crystalline acid found in meat and yeast and produced by the oxidation of nicotine.
Nichrome
An alloy of nickel and chromium used for heating elements.

Nickel
A metallic element that is malleable and ductile, and is resistant to corrosion in air or water, and hence is used as a protective coating.
Nickel Brass
A copper alloy containing zinc and a small quantity of nickel.

Nicotine

CH14N2

Colourless, very poisonous oily liquid.

Nicotinic Acid
Vitamin B3 is a crystalline acid found in meat and yeast and produced by the oxidation of nicotine.
Niningerite
Rare naturally occuring mineral of Magnesium Sulphide.
Niobium
As a pure metallic element it is very reactive and forms an extremely stable oxide when exposed to air which enhances its corrosion resistance.
Nitrate
The NO3- ion, formed by reaction of nitric acid with a base or a compound containing the NO3- ion.
Nitre
Old fashioned name for Potassium Nitrate.
Nitric Acid

HNO3

Colourless, corrosive, acid liquid that attacks most metals and other substances releasing nitrogen dioxide.

Nitric Oxide
A colourless gas that forms nitrogen dioxide in contact with air.
Nitrile
An organic compound which has a -C=N functional group.
Nitrite
The NO2- ion, formed by reaction of nitrous acid with a base or a compound containing the NO2- ion.
Nitrobenzene
A yellow liquid obtained from the action of concentrated nitric and sulphuric acid on benzene.
Nitrogen
A gaseous colourless and odourless element that makes up about 80% of the atmosphere.
Nitrogen Dioxide

NO2

An intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent air pollutant.

Nitrogen Monoxide

NO

A free radical and is an important intermediate in the chemical industry.

Nitrogen Oxides
Several air-polluting gases composed of nitrogen and oxygen which play an important role in the formation of photochemical smog.
Nitroglycerine

C3H5N3O9

A heavy, yellow or colourless, oily, explosive liquid obtained by nitrating glycerol.

Nitromagnesite
Naturally occuring Magnesium Nitrate.
Nitrous Oxide
Also known as laughing gas, an anaesthetic.
No
Nobelium is a man-made element with an atomic number of 102.
NO2
Chemical formula for Nitrogen Dioxide.
Nobel Prize
Awarded annually as per Alfred Nobel′s last will and testament.
Nobelium
A man-made element with an atomic number of 102.
Noble Gases
The gaseous chemical elements helium, neon, argon, krypton, xenon and radon, which are all placed in Group 0 of the Periodic Table.
Noble Metals
Metals, such as gold, silver and platinum, that show a marked reluctance to combine with other elements to form compounds.
Nonane

C9H20

A colourless volatile liquid, an ingredient of ordinary kerosene.

Noncrystalline
The solid state wherein there is no long-range atomic order. Sometimes used synonymously with the terms amorphous, glassy and vitreous.
Non-Destructive Hydrogenation
Hydrogen is added to a molecule that is unsaturated with respect ot hydrogen.
Nonelectrolyte
A substance which does not ionize in solution.
Non-Metal
A term usually reserved for those chemical elements that are very poor electrical conductors in the solid state and liquid states.
Non-Newtonian Fluid
A fluid whose viscosity changes when the gradient in flow speed changes.
Nonpolar Molecule
A molecule in which the center of positive charge and the center of negative charge coincide.
Non-Steady State Diffusion
The diffusion condition for which there is some net accumulation or depletion of diffusing species; the diffusion flux is dependent on time.
Nordic Gold
A 89% copper, 5% aluminium, 5% zinc and 1% tin alloy.

Normal Concentration
Used in chemistry to describe a solution having a concentration of 1 gram equivalent per litre.
NOx
Abbreviation of Nitrogen Oxides where x represents a varying proportion of oxygen.
Np
Neptunium is produced artificially by nuclear reaction between uranium and neutrons.
Nuclear Binding Energy
Energy needed to break an atomic nucleus into separate protons and neutrons.
Nuclear Energy
Energy stored in the nucleas of an atom.
Nucleate
To form a central part around which other parts can attach.
Nucleation
The initial stage in a phase transformation.
Nucleic Acid
A polymer made of repeating nucleotides. Examples are DNA and RNA.
Nucleoside
A nucleotide base bound to a five-carbon sugar.
Nucleotide
A molecule which is a basic building block of nucleic acids and which plays a key role in energy transfer in biochemical reactions.
Nucleotide Base
A heterocyclic nitrogen-containing base that is a constituent of nucleotides.
Nuclide
An atom or ion with a specified mass number and atomic number.
Nuclide Symbol
A symbol for an nuclide that contains the mass number as a leading superscript and the atomic number as a leading subscript.
Nylon
A synthetic polymer used in the manufacture of fibres.
O
Oxygen is a colourless and odourless element that is essential for most life forms on earth. It is also the most abundant element on earth.
O3
Allotropic form of oxygen containing three atoms in the molecule.
Octadecanoic Acid
Alternative name for Magnesium Stearate.
Octahedral Position
The void space among closed-packed, hard sphere atoms or ions for which there are six nearest neighbours.
Octal
A number system using the base-8, i.e., each digit can be any of 8 values, represented by the digits 0-7.
Octane
Flammable liquid compounds found in petroleum and natural gas.
Octane Number
A rating of the 'knock' characteristics of motor fuels.
Octet
A set of eight valence electrons.
Octet Rule
A guideline for building Lewis structures that states that atoms tend to gain, lose, or share valence electrons with other atoms in a molecule until they hold or share eight valence electrons.
Oil
An oil is any substance that is in a viscous liquid state at ambient temperatures or slightly warmer, and is both hydrophobic and lipophilic.
Oil of Bitter Almond
Old name for Benzaldehyde.
Oil of Mirbane
Old name for Nitrobenzene.
Oil of Vitriol
Alternative name for Sulphuric Acid.
Oleoresin
A natural plant product that contains oil and resins, an example is turpentine.
Olive Oil
Obtained from the fruit of Olea Europaea.
Open System
A system which can exchange both matter and energy with its surroundings.
Optical Activity
A substance that is capable of rotating plane-polarized light.
Optical Isomers
Stereoisomers that exist because of the presence of chiral centres.
Orbital
A wavefunction that describes what an electron with a given energy is doing inside an atom or molecule.
Order of Reaction
The sum of concentration exponents in the rate law for the reaction.
Ordering
Positioning of host and substitution ions in an ordered, repetitious pattern rather than in a random arrangement.
Ore
A natural mineral mined and treated for extraction of its components.
Organic Aerosol
Aerosol particles consisting predominantly of organic compounds, mainly C, H, and O, and lesser amounts of other elements.
Organic Chemistry
The branch of chemistry that deals with the properties and reactions of carbon-based compounds.
Organic Compound
Compounds that contain carbon chemically bound to hydrogen.
Organochromic Indicators
Coloured organic compounds that change colour when they chelate different metals.
Orichalchum
A Roman brass that consisted of 80% copper and 20% zinc.

Ormolu
An alloy of copper, zinc and tin in various proportions with at least 50% copper.

Orthophospheric Acid
Another name for Phosphoric Acid.
Os
Osmium is a member of the platinum group of metals and is commonly found in conjunction with these elements.
Osmiridium
Osmiridium (iridosmine) is a naturally occurring alloy of osmium and iridium. Used to make long-wearing tips for gold fountain-pen nibs.
Osmium
A member of the platinum group of metals and is commonly found in conjunction with these elements.
Osmometry
Determination of the average molecular weight of a dissolved substance from measurements of osmotic pressure.
Osmosis
Passage of solvent molecules from a dilute solution through a semipermeable membrane to a more concentrated solution.
Osmotic Pressure
Pressure which must be applied to a solution to prevent water from flowing in via a semipermeable membrane.
Oxalic Acid

H2C2O4

A relatively strong organic acid, being about 10,000 times stronger than acetic acid.

Oxidant
Alternative expression for Oxidizing Agent.
Oxidation
The loss of one or more electrons by an atom, molecule, or ion.
Oxidation Half Reaction
That part of a redox reaction that involves loss of electrons.
Oxidation Number
A number assigned to each atom to help keep track of the electrons during a redox-reaction.
Oxidation Reaction
A reaction where a substance loses electrons.
Oxidation-Reduction Reaction
A reaction in which electrons are transferred from a donor to an acceptor.
Oxide
A binary compound that contains oxygen in the -2 oxidation state.
Oxidizing Agent
Cause other substances to be oxidized in chemical reactions while they themselves are reduced.
Oxyacid
When one or more hydroxide (OH) groups are bonded to a central atom.
Oxygen
A colourless and odourless element that is essential for most life forms on earth. It is also the most abundant element on earth.
Oxygenated Fuel
Any fuel substance containing oxygen, such as ethanol, methanol, or biodiesel.
Ozone

O3

Allotropic form of oxygen containing three atoms in the molecule.

P
Phosphorus is a non-metallic element.
Pa
Protactinium is a radioactive element.
PAH
Abbreviation of Polynuclear Aromatic Hydrocarbons.
Palladium
A member of the platinum group of metals. It is silvery white in colour, is malleable and ductile, and is one of the most reactive in the group
Paracetamol
Another name for Acetaminophen.
Paraffin Oil
A term describing a whole series of saturated aliphatic hydrocarbons, also known as alkane hydrocarbons.
Paraffin Wax
Obtained as a residue from the distillation of petroleum.
Parent Isotope
An element that undergoes nuclear decay.
Partial Miscibility
Two liquids are considered partially miscible if shaking equal volumes of the liquids together results in a meniscus visible between two layers of liquid, but the volumes of the layers are not identical to the volumes of the liquids originally added.
Partial Oxidation
Occurs when a substoichiometric fuel-air mixture is partially combusted in a reformer, creating a hydrogen-rich syngas which can then be put to further use.
Partial Pressures
The pressure exerted by a certain gas in a mixture.
Particulate
Composed of distinct particles.
Parts Per Million
Used to describe the amount of a trace element or substance present in the main substance.
Passive Transport
Transport of a molecule across a membrane down a concentration gradient which does not require the input of energy.
Path Function
A property that is dependent on the path taken.
Path Length
In absorption spectroscopy, the length of a path taken by radiation through a sample.
Patina
A thin layer of corrosion products with a distinctive colouration that forms on a metal surface exposed to air and water.
Pb
Lead is a soft, malleable and ductile metallic element that has been known of and used since prehistoric times.
PbCO3
Lead II Carbonate, decomposes readily into Lead II Oxide and carbon dioxide at 200°C and can be reduced to lead using carbon monoxide.
PbCrO4
Lead II Chromate IV, used as a pigment due to strong yellow colour.
PbO
Lead monoxide varies in colour from pale yellow to brown, used in the manufacture of glass, paints, varnishes and glazes.
PbO2
Lead dioxide a dark brown powder, strong oxidizing agent.
Pd
Palladium is a member of the platinum group of metals. It is silvery white in colour, is malleable and ductile, and is one of the most reactive in the group
Pearl Ash
An old fashioned name for Potassium Carbonate.
Pearlite
A lamellar aggregate of ferrite and cementite.
Peat
Partially carbonized vegetable material, usually found in bogs.

Pentafluoride Antimony
Alternative name for Antimony Pentafluoride.
Pentane

C5H12

The fifth member of the paraffin series. Pentane exists in three isomeric forms.

Pentanol

C5H11OH

A colourless liquid at room temperature with a choking aroma.

Peptidase
An enzyme that hydrolyzes a peptide bond.
Peptide
A short polymer made by linking together amino acid molecules.
Peptide Bond
A planar, amide linkage between the α-amino group of one amino acid and the α-carboxyl group of another, with the elimination of a molecule of water.
Percent Yield
Equals experimental yield divided by theoretical yield times 100%.
Perfect Crystal
A crystal with no defects or impurities, made of completely identical repeating subunits.
Perfluorocarbons
By-products of aluminum smelting and uranium enrichment. Also replace chlorofluorocarbons in manufacturing semiconductors.
Perfluoromethane
Alternative name for Tetrafluoromethane.
peri-Ethylenenaphthalene
Another name for Acenaphthene.
Periodic Law
The properties of the elements are periodic functions of their atomic numbers.
Periodic Table
The most commonly used arrangement of the periodic system.
Periodic Trend
A regular variation in element properties with increasing atomic number that is ultimately due to regular variations in atomic structure.
Peritectic
An isothermal reversible reaction in metals where a liquid phase reacts with a solid phase to produce a single, different, solid phase upon cooling.
Permanent Hardness
Water hardness that remains after boiling the water, mainly due to dissolved calcium sulphate.
Permanganic Acid
Alternative name for Manganese VII Oxide.
Permangante of Potash
Old fashioned name for Potassium Manganate VII.
Permeability
  1. passage or diffusion of a gas, vapor, liquid, or solid through a material without physically or chemically affecting it.
  2. Term used to express various relationships between magnetic induction and magnetizing force; either absolute permeability or specific (relative) permeability.
Perspex
Tradename for Polymethyl Methacrylate Resin.
Pesticide
A chemical or biological agent that kills pests.
Petrol
A volatile, flammable liquid mixture of hydrocarbons, obtained from petroleum and used as a fuel for internal-combustion engines.
Petroleum
An oily, thick, flammable, usually dark coloured liquid that is a form of bitumen or a mixture of various hydrocarbons, occurring naturally in various parts of the world and often separated by distillation into petrol, naphtha, benzene, kerosene and paraffin.

Peukert Equation
A formula that shows how the available capacity of a lead-acid battery changes according to the rate of discharge.
PFCs
Abbreviation of Perfluorocarbons.
pH
Measures the acidity of a solution. It is the negative logarithm of the concentration of the hydrogen ions in a substance.
Pharmacognosy
Identification, isolation, and characterization of biologically active substances in living things.
Pharmacology
The study of drugs, which includes determination of biological activity, biological effects, breakdown and synthesis, and delivery.
Phase Boundary
A surface where two samples of matter with different properties are in contact.
Phase Change
The change from gas to liquid to solid.
Phase Separation
The phenomenon of a separation of a liquid or vapour into two or more physically distinct and mechanically separable portions or layers.
Phenol
Also known as carbolic acid. It is used as a strong disinfectant.
Phenolic Resin
A condensation reaction polymer. A key characteristic of phenolic resin is the ability to withstand high temperature, along with mechanical load with minimal deformation or creep. In other words, cured phenolic resin provides the product rigidity necessary to maintain structural integrity and dimensional stability even under severe conditions.

Phenyl
A molecular group or fragment formed by abstracting or substituting one of the hydrogen atoms attached to a benzene ring.
Phenyl Methyl Ketone
Alternative name for Acetophenone.
Phenylamine
Alternative name for Aniline.
Philosopher′s Wool
An old name for Zinc Oxide.
Phlogisticated Air
An old name for Nitrogen.
Phlogiston
A hypothetical elastic fluid which was seen as a metalizing and combustible principle.
Phosphate
An ion, compound, or salt containing phosphorus and oxygen.
Phosphodiester Linkage
A chemical grouping that contains two alcohols esterified to one molecule of phosphoric acid.
Phospholipid
A lipid containing one or more phosphate groups.
Phosphor Bronze
An alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%.

Phosphorescence
The property of a material whereby it continues to emit visible light after it has been illuminated by ultraviolet light.
Phosphoric Acid

H3PO4

An inorganic acid.

Phosphorolysis
Cleavage of a compound with phosphate as the attacking group.
Phosphorus
A non-metallic element.
Photo Etching
Chemical process of removing unwanted material in producing printed circuit boards.
Photochemistry
The study of the effects of light on chemical reactions.
Physical Change
A change which does not transform one substance into another.
Physical Chemistry
A branch of chemistry that studies chemical phenomena from a physical and mathematical perspective.
Physical Property
Measurement of a physical property may change the arrangement but not the structure of the molecules of a material.
Phytochemicals
Materials extracted from plant tissue.
Phytochemistry
The study of substances found in plants.
Pi Bonds
A type of covalent bond in which the electron density is concentrated around the line bonding the atoms.
Piano Wire
High quality steel wire used for making springs.

Piezoelectric
Any material which provides a conversion between mechanical and electrical energy.
Pig Iron
The intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux.

Pinchbeck
A cheap bronze alloy.
Pitchblende
The most important Uranium ore.
pK
The negative logarithm of an equilibrium constant.
Plastic
A solid material in the primary ingredient of which is an organic polymer of high molecular weight.
Plasticizer
A low molecular weight polymer additive that enhances flexibility and workability and reduces stiffness and brittleness.
Platinum
A lustrous, malleable and ductile metallic element.
Plumbago
The natural allotropic form of carbon.
Plumbum
Latin for lead, hence the symbol Pb.
Plutonium
A product of the radioactive decay of neptunium.
Pm
Promethium is a radioactive element of the rare earth series.
PM0.1
Ultrafine particles.
Po
Polonium is a radioactive element.
pOH
Measures the basicity of a solution. It is the negative logarithm of the concentration of the hydroxide ions.
Point Defect
A crystalline defect associated with one or, at most, several atomic sites.
Polar Bond
A bond involving electrons that are unequally shared.
Polar Molecules
Molecule with a partial charge.
Polarization
For an atom, the displacement of the centre of the negatively charged electron cloud relative to the positive nucleus, which is induced by an electric field.
Polonium
A radioactive element.
Polyatomic Ion
An ion formed by the loss or gain of electrons from a molecule or chemical group composed of two or more atoms.
Polyatomic Molecule
An uncharged particle that contains more than two atoms.
Polycarbonate
A thermoplastic that can be shaped and formed through a number of manufacturing processes. It machines well and can be solvent bonded and welded. It is tough and resistant to damage which is an ideal property for a mobile phone. If dropped, a mobile phone with a polycarbonate casing is likely to survive undamaged. It is an insulator, often used to insulate electrical circuits. Supplied in a range of colours.

Polycrystalline
Referring to crystalline materials that are composed of more than one crystal or grain.
Polydentate Ligand
A ligand that has more than one atom that coordinates directly to the central atom in a complex.
Polyethylene
Plastic used heavily in the packaging industry.

Polyimide
a polymer of imide monomers.
Polymer
A large molecule formed by the linking together of many smaller molecules known as monomers.
Polymeric Dispersant
A water-soluble polymer that acts as a suspending agent promoting the suspension of particles in water so that they resist settling.
Polymerization
The process by which monomers are joined together to give a polymer.
Polymerize
To link smaller molecules together to form a larger molecule.
Polymethyl Methacrylate Resin
Commonly known as perspex or lucite, a transparent plastic.

Polynuclear Aromatic Hydrocarbons
Aromatic hydrocarbons with two or more (up to five or six) benzene rings joined in various, more or less clustered forms.
Polyphosphate
A chemical compound formed by the adjoining of phosphate ions.
Polysaccharide
A carbohydrate consisting of a large number of linked monosaccharide units.
Polystyrene
Expanded polystyrene was the first foamed polymer. It is the white rigid plastic used for thermal insulation and in flotation devices.

Polytetrafluoroethylene
Commonly known as Teflon, a thermoplastic polymer used for non-stick coatings and bearings.

Polythene
Alternative name for Polyethylene.
Polyurethane
Polymer composed of a chain of organic units joined by carbamate links.

Polyvinyl Acetate
A colorless, thermoplastic, water soluble, resinous high polymer derived from the polymerization of vinyl acetate with a catalyst. Abbreviated as PVA.

Polyvinyl Alcohol

(C2H4)n

Odorless and nontoxic with excellent film forming, emulsifying, and adhesive properties with resistance to oil, grease and solvent.

Polyvinyl Chloride
Plastic used in many different forms. Commonly abbreviated as PVC.

Polyvinylpyrrolidone
Soluble in water and other polar solvents. Used as a coating or an additive in coatings.

Ponderous Spar
Old name for Barium Sulphate.
Positive Charge
The electrical potential acquired by an atom which has lost one or more electrons; a characteristic of a cation.
Potable Water
Another name for drinking water.
Potash
Old fashioned name for Potassium Carbonate made from the ashes of burnt wood.
Potassium
A soft, silvery coloured metal, which like other members of the alkali group of metals, is extremely reactive.
Potassium Acetate

KC2H3O2

The potassium salt of acetic acid, used as a deicer instead of chloride salts such as calcium chloride or magnesium chloride.

Potassium Bromide

KBr

A white crystalline salt used in photography. It was used in medicine as a sedative.

Potassium Carbonate

K2CO3

A white very soluble deliquescent salt.

Potassium Chloride

KCl

White crystalline solid.

Potassium Fluoride

KF

White crystalline solid.

Potassium Hydroxide

KOH

A white deliquescent solid that dissolves in water to give an alkaline solution.

Potassium Iodide

KI

White crystalline solid.

Potassium Manganate VII

KMnO4

Deep purple, crystalline, soluble salt. Dissolves in water to produce a strong oxidizing agent. Used as a disinfectant.

Potassium Nitrate

KNO3

The salt of potassium and nitric acid. Used in pyrotechnics, explosives, the manufacture of glass and as a fertilizer.

Potassium Oxide

K2O

Yellowish white yo grey crystalline solid.

Potassium Permanganate
Deep purple, crystalline, soluble salt.
Potassium Peroxide

K2O2

Yellow or orange solid.

Potassium Sulphide

K2S

White, yellow, red or brown.

Potassium Superoxide

KO2

Yellow crystalline solid.

Potin
An ancient alloy of copper, zinc, lead and tin that was used to make coins.

Powdered Baking Ammonia
Alternative name for Ammonium Bicarbonate.
Power Density
Characteristic parameter of a battery/electrical power source indicating its electrical power per unit weight or volume.
ppm
Abbreviation for Parts Per Million.
PPMVD
The part per million concentration that is determined by comparing the volume of one constituent with the volume of the other constituents with the exception of moisture.
Pr
Praseodymium is a soft, white metal and a member of the lanthanide group of elements.
Praseodymium
A soft, white metal and a member of the lanthanide group of elements.
Precipitate
A solid that appears in the form of fine particles in what was previously a clear solution because of a chemical reaction.
Precipitation
The conversion of a dissolved substance into insoluble form by chemical or physical means.
Precipitation Heat Treatment
Artificial aging in which a constituent precipitates from a supersaturated solid solution.
Prepreg
A continuous fibre reinforcement pre-impregnated with a polymer resin which is then partially cured.
Primary Bond
Interatomic bonds that are relatively strong and for which bonding energies are relatively large.
Primary Standard
A stable, high-purity material used in titrations and other chemical analyses to prepare solutions of precisely known concentration.
Prince′s Metal
An alloy resembling brass, consisting of three parts of copper to one of zinc.

Product
A substance that is produced during a chemical change.
Promethium
A radioactive element of the rare earth series.
Propane

C3H8

A member of the alkane series, a colourless, odourless gas at room temperature. In liquid form it is often referred to as Liquid Petroleum Gas (LPG).

Propanol

CH3CH2CH2OH

Used as an inexpensive alcohol. Also known as propyl alcohol.

Propanone
Alternative name for Acetone.
Propargyl Alcohol

C3H4O

The simplest stable alcohol containing an alkyne functional group.

Propene

C3H6

A colourless highly flammable gas.

Propene Acid
Alternative name for Acrylic Acid.
Propenoic Acid
Alternative name for Acrylic Acid.
Propyl Alcohol
Alternative name for Propanol.
Propylene
Alternative name for Propene.
Propylene Glycol

C3H8O2

A colourless, nearly odorless, clear, viscous liquid with a faintly sweet taste, hygroscopic and miscible with water, acetone, and chloroform.

Protactinium
A radioactive element.
Protein
A very large, naturally occurring polyamide formed from a selection of the 20 or so naturally occurring amino acids.
Protium
The lightest element of hydrogen of unit mass and the most prevalent in the universe.

Proton Acceptor
The acceptor of a proton in an acid-base reaction.
Proton Donor
Because a free H+ ion is technically a bare proton, acids are sometimes referred to as proton donors because they release hydrogen ions in solution.
Prussic Acid
A solution of Hydrogen Cyanide in water.
Pseudocore
Electrons in d or f subshells which are outside the noble gas core.
Pt
Platinum is a lustrous, malleable and ductile metallic element.
PTFE
Abbreviation of Polytetrafluoroethylene, a thermoplastic polymer used for non-stick coatings and bearings.
Pu
Plutonium is a product of the radioactive decay of neptunium.
Pumice
A light porous stone of mixed silicates.

Pure Air
An old name for oxygen
Pure Substance
A form of matter that has both definite composition and distinct properties.
Putrescine

C4H12N2

Related to cadaverine and produced by the breakdown of amino acids in living and dead organisms.

PV Diagram
A plot of pressure vs. volume.
PVA
Abbreviation of Polyvinyl Acetate.
PVC
Abbreviation of Polyvinyl Chloride.
Pyrex Glass
A type of glass that is resistant to heat and chemical attack. Often used in cookware and in laboratory equipment.

Pyrolyser
An instrument that breaks complex molecules into constituents by using heat.
Pyrolysis
Thermal degradation of waste in the absence of air to produce char, pyrolysis oil and syngas.
Pyrophoric
Catches fire spontaneously when exposed to air at normal room temperature.
Qualitative Analysis
A chemical analysis that detects the presence of a substance in a sample.
Quantative Analysis
A chemical analysis that determines the concentration of a substance in a sample.
Quantative Structure Activity Relationship
A mathematical connection between chemical structure and biological activity, established by statistical analysis or pattern recognition techniques.
Quartz

SiO2

Found naturally as faceted crystals. Its birefringent properties are used in the production of optical quarter-wave plates and polarizers.

Quicklime
Another name for Calcium Oxide.
Quicksilver
Ancient name for Mercury.
Quire
25 sheets of paper.
R
The constant that appears in the ideal gas equation.
Ra
Radium is a radioactive element of the alkaline earth metals. White in colour and properties close to barium.
Racemic Mixture
A mixture that has equal amounts of left- and right-handed enantiomers of a chiral molecule.
Radioisotope
A radioactive isotope.
Radium
A radioactive element of the alkaline earth metals. White in colour and properties close to barium.
Radon
A radioactive element and the heaviest of the nodle gases.
Random Copolymer
A polymer in which two different mer units are randomly distributed along the molecular chain.
Rankine Temperature Scale
An absolute scale of temperature based on degrees Farenheit.
Raoult′s Law
The vapour pressure of a solvent in an ideal solution equals the mole fraction of the solvent times the vapour pressure of the pure solvent.
Rare Earth
An oxide of a rare earth element.
Rare Earth Element
A metallic element that belongs to Group 3B or to the lanthanide series.
Rate Law
A rate law or rate equation relates reaction rate with the concentrations of reactants, catalysts, and inhibitors.
Rate of Reaction
The rate at which the concentration of a product increases or the concentration of a reactant decreases with time.
Rb
Rubidium is a soft and highly reactive member of the alkali group of metals.
Rb2O
Chemical formula for Rubidium Oxide.
Rb2O2
Chemical formula for Rubidium Peroxide.
Rb2S
Chemical formula for Rubidium Sulphide.
RbBr
Chemical formula for Rubidium Bromide.
RbCl
Chemical formula for Rubidium Chloride.
RbF
Chemical formula for Rubidium Fluoride.
RbI
Chemical formula for Rubidium Iodide.
RbO2
Chemical formula for Rubidium Superoxide.
Re
A rare element that is a silvery coloured metal which resists corrosion and oxidation but slowly tarnishes in moist air.
Reactants
Substances initially present in a chemical reaction.
Reaction Mechanism
A list of all elementary reactions that occur in the course of an overall chemical reaction.
Reaction Order
The sum of concentration exponents in the rate law for the reaction.
Reaction Quotient
The product of the concentrations of the products, divided by the product of the concentrations of the reactants, for a chemical reaction which is not necessarily at equilibrium.
Reaction Rate
A reaction rate is the speed at which reactants are converted into products in a chemical reaction.
Reactive Intermediate
A highly reactive substance that forms and then reacts further during the conversion of reactants to products in a chemical reaction.
Reactor
Vessel which contains nuclear or chemical reactions.
Reagent
A substance or mixture that is useful in chemical analysis or synthesis.
Rearrangement Reaction
A reaction in which a reactant and product are isomers of each other.
Reaumur Temperature Scale
On the Reaumur temperature scale, abbreviated to R, the ice point is 0°R and the steam point is 80°R.
Receptor Site
A molecule or surface in a cell that recognizes and binds to a specific messenger molecule, leading to a biological response.
Reciprocal Lattice
A group of points arranged about a centre in such a way that the line joining each point of the centre is perpendicular to a family of planes in the crystal, and the length of this line is inversely proportional to their inter planar distance.
Recombination
The process by which a positive and a negative ion join to form a neutral molecule or other neutral particle, also process by which radicals or dissociations species join to form molecules.
Recrystallization
The formation of a new set of strain-free grains within a previously cold-worked material; normally an annealing heat treatment is necessary.
Red Iron Oxide
Old name for Iron III Oxide.
Redox Indicator
An organic molecule that has reduced and oxidized forms with different colours, interconversion of the reduced and oxidized forms of the indicator must be reversible.
Redox Reaction
A reaction in which one or more electrons are transferred.
Redox Titration
A titration based on a redox reaction.
Reducing Agent
A substance that reduce another substance by supplying electrons to it.
Reductant
A substance that reduce another substance by supplying electrons to it.
Reduction
A gain of one or more electrons by an atom, molecule, or ion.
Reduction Half Reaction
That part of a redox reaction that involves gain of electrons.
Reference Oil
An oil of known performance characteristics, used as a basis for comparison.
Reformate
The output of a fuel reformer.
Reforming
A chemical process in which hydrogen-containing fuels react with steam, oxygen, or both to produce a hydrogen-rich gas stream.
Reformulated Petrol
Petrol that is blended so that, on average, it reduces volatile organic compounds and air toxic emissions significantly relative to conventional petrols.
Refractory
A metal or ceramic that may be exposed to extremely high temperatures without deteriorating rapidly or without melting.
Reid Vapour Pressure
A standard measurement of a liquid′s vapour pressure in psi at 100°F. It is an indication of the propensity of the liquid to evaporate.
Relative Density
The ratio of the density of the substance to that of water at 4°C
Renewable Energy
Energy obtained from sources that are essentially inexhaustible, unlike fossil fuels.
Residue
The substances left after an evaporation or distillation.
Resonance Effect
Difference in electron density at particular points in a molecule.
Reverse Osmosis
Pressure is applied to the more concentrated solution to force the flow of solvent to go from more concentrated to more dilute solution.
rhenium
A rare element that is a silvery coloured metal which resists corrosion and oxidation but slowly tarnishes in moist air.
Rhodium
One of the rarest metals on earth.
Riboflavin
Commonly known as vitamin B2.
Rich Combustion
Having a relatively high proportion of fuel to oxidizer. Having a value greater than stoichiometric.
Rocket Propellant
Any agent used for consumption or combustion in a rocket and from which the rocket derives its thrust, such as a fuel, oxidizer, additive, catalyst, or any compound or mixture of these.
Roses Alloy
A fusible alloy consisting of 50 per cent bismuth, 25 percent lead and 25 per cent tin.

Rosin
Natural resin obtained from living pine trees or from dead tree stumps and knots.

Rubbing Alcohol
Another name for Propanol.
Rubidium
A soft and highly reactive member of the alkali group of metals.
Rubidium Bromide

RbBr

White crystalline solid.

Rubidium Chloride

RbCl

White crystalline solid.

Rubidium Fluoride

RbF

White crystalline solid.

Rubidium Hydride

HRb

White crystalline solid.

Rubidium Iodide

RbI

White crystalline solid.

Rubidium Oxide

Rb2O

Yellow to yellow brown crystalline solid.

Rubidium Peroxide

Rb2O2

White, yellow or dark brown crystalline solid.

Rubidium Sulphide

Rb2S

White, yellow or red.

Rubidium Superoxide

RbO2

Orange crystalline solid.

Rust
A corrosion product consisting of hydrated oxides of iron. This term is only applied to ferrous alloys.
Ruthenium
A lustrous, silvery coloured metal which is unaffected by air, water and acids, but is soluble in fused alkalis.
Safety Data Sheet
OSHA has replaced MSDS with SDS in 2013 under 29CFR Part 1910.1200.
Sal Ammoniac
Old name for Ammonium Chloride.
Salifiable
Capable of reacting with an acid to form a salt.
Salt
Sodium chloride.
Salt Bridge
A tube that allows two solutions to be in electrical contact without mixing in an electrochemical cell.
Salt of Tartar
An old fashioned name for Potassium Carbonate.
Salt of Wormwood
Old fashioned name for Potassium Carbonate.
Saltpetre
Old fashioned name for Potassium Nitrate or Sodium Nitrate.
Samarium
A relatively stable element in dry air but oxidises on contact with moisture.
Sand
A term generally given to rock with a grain size between 1/16mm and 2mm.
Sapid
To have a decided, yet pleasant taste.
Saponaceous
To be soapy, slippery, sometimes foaming.
Saponification
The hydrolysis of esters using hot sodium hydroxide solution to produce the salt of a carboxylic acid.
Saturated Fat
A lipid that contains no carbon-carbon double bonds.
Saturated Solution
A solution which does not dissolve any more solute.
Sb2O3
Chemical formula for Antimony Trioxide.
Sb2O4
Chemical formula for Antimony Tetroxide.
Sb2O5
Chemical formula for Antimony V Oxide.
Sb2Se3
Chemical formula for Antimony Triselenide.
SbBr3
Chemical formula for Antimony Tribromide.
SbCl3
Chemical formula for Antimony Trichloride.
SbCl5
Chemical formula for Antimony Pentachloride.
SbF3
Chemical formula for Antimony Trifluoride.
SbF5
Chemical formula for Antimony Pentafluoride.
SbH3
Chemical formula for Antimony Hydride.
SbI3
Chemical formula for Antimony Triiodide.
SbO2
Chemical formula for Antimony Tetroxide.
Scandium
A soft, silvery white metal.
SDRAM
Abbreviation for Synchronous Dynamic Random Access Memory, SDRAM delivers bursts of data at high speeds using a synchronous interface.
SDS
Abbreviation of Safety Data Sheet.
Sea Water
Contains the majority of the common elements in small quantities.
Sealing Wax
The wax used to seal confidential documents.
Second Ionization Energy
The energy needed to remove an electron from an isolated +1 ion.
Second Order Reaction
A reaction with a rate law that is proportional to either the concentration of a reactant squared, or the product of concentrations of two reactants.
Sedimentation
Separation of a dense material from a less dense material by allowing the denser material to settle out of the mixture.
Selenium
The electrical properties of selenium are of particular interest as it is both photovoltaic and photoconductive.
Semi-Metal
An element with both metallic and nonmetallic properties e.g. silicon.
Semi-Permeable Membrane
A membrane that allows some but not all of the components in a mixture to pass through it.
Sensible Energy
The internal energy of a system associated with kinetic energies (molecular translation, rotation, and vibration; electron translation and spin; and nuclear spin) of the molecules.
Sesquioxide
An oxide containing three atoms of oxygen with two atoms of another element.
SF6
Chemical formula for Sulphur Hexafluoride.
Shellac
A coating made from purified lac dissolved in alcohol, often bleached white.

Shells
Where the electrons generally stay.
SiC
Silicon Carbide, used extensively as a grinding compound and in abrasive wheels.
Signs and Symbols
A list of signs and symbols.
SiH4
Chemical formula for Silane.
Silane

SiH4

A gas at room temperature, undergoes spontaneous combustion in air without any external ignition.

Silica
Another name for Silicon Dioxide.
Silica Gel
Precipitated silica acid in the form of lustrous granules, especially prepared for absorption of various vapours. Mildly toxic.

Silicane
Alternative name for Silane.
Silicon
Exists in two allotropic forms; brown silicon is a powder, whereas crystalline (metallic) silicon is grey and it is the latter which is more widely used.
Silicon Carbide

SiC

Used extensively as a grinding compound and in abrasive wheels.

Silicon Dioxide

SiO2

Known for its hardness since antiquity.

Silicon Hydride
Alternative name for Silane.
Silicon Iron
Adding silicon to low-carbon iron increases both hardness and electrical resistivity.
Silicon Nitride

N4Si3

Excellent thermal shock resistance, ability to withstand high structural loads at high temperatures and superior wear resistance.

Silicon Tetrahydride
Alternative name for Silane.
Silk
Protein based material obtained from cocoons of the silkworm.

Silver
A pure white metallic element. The best electrical conductor and used in photographic emulsions.
Silver Bromide

AgBr

Pale yellow insoluble salt used in photography.

Silver Iodide

AgI

Yellow crystalline solid.

Silver Nitrate

AgNO3

A white soluble crystalline salt used in marking inks, medicine and chemical analysis.

Silver Sand
A sand with a very low iron content.
Silver Sulphide

Ag2S

Black or grey-black crystalline solid. The most important ore of silver, known as Argentite.

Simple Diffusion
The unassisted movement of molecules across a membrane to a region of lower concentration.
Single Bond
When an electron pair is shared by two different elements.
SiO2
Chemical formula for Fused Silica.
Slate
Fine grained metamorphic rock with strong cleavage planes.
Slush Hydrogen
A mixture of liquid and frozen hydrogen that is denser than liquid hydrogen.
Slush Oxygen
A mixture of liquid and frozen oxygen that is denser than liquid oxygen.
SnCl2
Chemical formula for Tin II Chloride.
SnF2
Chemical formula for Tin II Fluoride.
SnF4
Chemical formula for Tin IV Fluoride.
SnH4
Chemical formula for Tin IV Hydride.
SnO
Chemical formula for Tin II Oxide.
SnO2
Chemical formula for Tin IV Oxide.
SO2
Chemical formula for Sulphur Dioxide.
Soap
A salt of a fatty acid.
Soda Ash
Alternative name for Sodium Carbonate.
Sodium
A soft, silvery coloured metal which, like other members of the alkali group of metals, is extremely reactive.
Sodium Carbonate

Na2CO3

Commonly known as washing soda or soda ash. Synthetically produced in large quantities from common salt using the Solvay process.

Sodium Chloride

NaCl

Commonly known as table salt.

Sodium Glutamate
More commonly known as Monosodium Glutamate.
Sodium Hydride

NaH

White to silver coloured solid.

Sodium Hydroxide

NaOH

A caustic metallic base used in the manufacture of pulp, textiles, drinking water, soaps and detergents.

Sodium Hypochlorite

NaOCl

Sold as a solution under a variety of trade names for use as liquid bleach.

Sodium I Bromide

NaBr

White crystalline solid.

Sodium I Fluoride

NaF

White crystalline solid.

Sodium I Iodide

NaI

White crystalline solid.

Sodium I Oxide

NaO2

Yellow crystalline solid.

Sodium Nitrate

NaNO3

A white solid which is very soluble in water, used as an ingredient in fertilizers, explosives, and in solid rocket propellants, as well as in glass and pottery enamels.

Sodium Oxide

Na2O

White solid.

Sodium Peroxide

Na2O2

Pale yellow solid.

Sodium Silicate

Na2O3Si

Available in aqueous solution and in solid form and is used in cements, passive fire protection, refractories, textile and lumber processing, and automobiles.

Sodium Superoxide
Old name for Sodium I Oxide.
Sol
A colloid with solid particles suspended in a liquid.
Solidification Range
The temperature between the liquidus and solidus.
Solubility
The solubility of a substance is its concentration in a saturated solution.
Solubility Product
The equilibrium constant for a reaction in which a solid ionic compound dissolves to give its constituent ions in solution.
Solubilizing Group
A group or substructure on a molecule that increases the molecule′s solubility.
Soluble
Capable of being dissolved in a solvent, usually water.
Soluble Salt
An ionic compound that dissolves in a solvent, usually water.
Solvent Extraction
A method for separating mixtures by exploiting differences in the solubilities of the components.
Soot
Sub-micron size particles, primarily carbon, created in combustion as products of incomplete combustion.
Sorb
To take up gas by sorption.
Sorbate
Gas taken up by a sorbent.
Sorbent
The material which takes up gas by sorption.
Sorption
Assimilation of molecules of one substance by a material in a different phase.
Sour Water
Waste waters containing fetid materials, usually sulphur compounds.
Spectator Ion
An ion that appears as both a reactant and a product in an ionic equation.
Spectrometer
An instrument which measure the position of spectral lines.
Spectrophotometry
Determination of the concentration of a material in a sample by measurement of the amount of light the sample absorbs.
Spectroscopy
Study of a radiation spectrum, emitted, absorbed or diffused.
Sphalerite
The mineral name for Zinc Sulphide, the most common ore of Zinc.
Spirit
An essence or extract that can be prepared from another substance as by distillation. Can mean alcohol.
Spirit of Alum
An old name for sulphuric acid.
Spirit of Hartshorn
An old name for ammonia as it was prepared from animal hooves and horns.
Stability
The ability to maintain normal characteristics.
Stabilizer
A substance that makes a mixture more stable.
Stainless Steel
Any steel containing at least 10.5% Cr as the principal alloying element.
Stainless Steel 303
18% chromium, 9% nickel free machining stainless. It offers good corrosion resistance with better machinability.

Stainless Steel 304
Most versatile and widely used stainless steel. It is also known as 18/8 from the nominal composition of type 304 being 18% chromium and 8% nickel.

Stainless Steel 310
Very tough and ductile, has good resistance to oxidation in continuous service up to 1150°C used for furnace components.

Stainless Steel 316
Better overall corrosion resistance properties than 304 and higher creep strength at elevated temperatures. 316 resists chloride attack and is often selected for use in marine atmospheres.

Stainless Steel 431
Martensitic stainless steel with excellent impact strength at high hardness levels with the best corrosion resistance of any martensitic stainless steels.

Standard Cell Voltage
The reversible voltage of an electrochemical cell with all active materials in their standard states.
Standard Electrode Potential
The reversible potential of an electrode with all the active materials in their standard states.
Standard Entropy of Reaction
A change in entropy associated with a reaction involving substances in their standard states.
Standard Molar Entropy
The entropy of one mole of a substance in its standard state.
Standard Molar Volume
The volume of 1 mole of an ideal gas at STP, equal to 22.414 litres.
Standard Solution
A solution of precisely known concentration.
Standard Temperature and Pressure
Often abbreviated as stp or STP it is a temperature of 0°C and a pressure of 101325Nm-2.
Stannane
Old name for Tin IV Hydride.
Stannic Fluoride
Old name for Tin IV Fluoride.
Stannic Oxide
Old name for Tin IV Oxide.
Stannous Fluoride
Old name for Tin II Fluoride.
Stannous Oxide
Old name for Tin II Oxide.
Stannum
The old name for Tin and from where the chemical symbol Sn was derived.
Starch
A polysaccharide used by plants to stockpile glucose molecules.
State Property
A state property is a quantity that is independent of how the substance was prepared.
Stationary Phase
A substance that shows different affinities for different components in a sample mixture in a separation of the mixture by chromatography.
Steam
The gas phase of water.
Steam Reforming
The process for reacting a hydrocarbon fuel, such as natural gas, with steam to produce hydrogen as a product.
Steel
An iron-based alloy containing manganese, usually carbon, and other alloying elements.
Steel EN31
A high carbon alloy steel which achieves a high degree of hardness with compressive strength and abrasion resistance.

Steel EN351
Bright / black 3/4% nickel chromium case hardening steel.

Steel EN353
Bright / black 1.1/4% nickel chromium case hardening steel.

Steel EN42
A 0.70/0.85% carbon steel which is normally heat treated to achieve high hardness and for the production of springs.

Steel EN44
Wear-resistance makes it ideal for edge tools and scraper blades.

Steel EN45
A manganese spring steel. Untempered EN45 is harder than mild steel, and will not suffer as much from burs or require as much repair.

Steel EN47
High ratio of yield point to tensile strength and torsional fatigue strength.

Steel EN9
An unalloyed medium carbon steel.

Stereochemistry
The study of how the properties of a compound are affected by the spatial positions of groups within its molecules.
Stereoisomerism
These are molecules with the same structural formula but their atoms have different positions in space.
Stibine
Old name for Antimony Hydride.
Stibium
The old name for Antimony and from where the chemical symbol Sb was derived.
Stibnite
The main source of antimony, a widely distributed but not very plentiful ore.
Stoichiometric Combustion
Just sufficient air is present for complete combustion of the fuel.
Straight Oil
A mineral oil containing no additives.
Stripping
A technique for removing volatile components in a mixture by bubbling a stream of an chemically unreactive gas through the sample, and then scrubbing the nitrogen through a solution or solid adsorbent that can recover the volatile materials.
Stripping Analysis
A group of electroanalytical techniques for the determination of trace amounts of substances.
Strong Acid
An acid that completely dissociates into hydrogen ions and anions in solution.
Strong Base
A base that completely dissociates into ions in solution.
Strong Ligand
A ligand that causes a large crystal field splitting which results in a low-spin complex.
Strontium
Forms a protective stable oxide coating but it will burn in air and reacts with water.
Structural Formula
A formula which shows the arrangement of the atoms in a molecule.
Structural Isomerism
These are molecules with the same molecular formula but with different structural arrangements of atoms.
Styrene

C8H8

Colourless oily liquid that evapourates easily and has a sweet smell, it is the precursor to polystyrene and several copolymers.

Styrene Acrylonitrile
A copolymer plastic consisting of styrene and acrylonitrile widely used in place of polystyrene owing to its greater thermal resistance.

Styrene Butadiene
A synthetic rubber copolymer consisting of styrene and butadiene. Good abrasion resistance and ageing stability when protected by additives and as such is widely used in car tyres where it is blended with natural rubber.

Sublimate
Solid or concrete products of sublimation. Not powder.
Sublimation
The transition of a substance directly from the solid phase to the vapour phase, or in reverse, without going through the liquid phase.
Subshell
A set of electrons with the same azimuthal quantum number.
Substance
Material objects that can undergo various transformations related to artificial or natural phenomena.
Substitution Reaction
A reaction in which an atom or fragment within a molecule is replaced with another.
Sugars
Sugars are a group of carbohydrates, soluble in water and having a sweet taste.
Sulphate
A compound containing the SO42- ion.
Sulphite
A compound containing the SO32- ion.
Sulphur
A non-metallic element occurring in several allotropic forms.
Sulphur Dioxide
A colourless gas formed when sulphur is burnt in air and forms sulphurous acid when dissolved in water.
Sulphur Hexafluoride

SF6

A colourless, non-toxic and non-flammable gas at room temperature and pressure.

Sulphur Monoxide

SO

Only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 (disulphur dioxide).

Sulphur Trioxide

SO3

In the gaseous form, this species is a significant pollutant, being the primary agent in acid rain.

Sulphuric Acid

H2SO4

An oily, corrosive liquid that acts as a strong acid when dissolved in water.

Sulphurous Acid

H2SO3

A colourless liquid that acts as a weak acid when dissolved in water.

Super Beryllia
Alternative name for Beryllium Oxide.
Supercooled
Liquids at temperatures below their normal freezing points are said to be "supercooled".
Superoxide
A binary compound containing oxygen in the -½ oxidation state.
Supersaturated Solution
A solution that has a concentration of solute that is higher than its solubility.
Surface Combustion
A method of causing a mixture of air and gas to burn by bringing it into contact with a suitable porous surface.
Surfactant
A material that spreads along a surface, changing the properties of the surface.
Suspension
A system consisting of small particles dispersed in a liquid. The system of springs, links and absorbers that suspends a vehicle above its wheels.
Svedberg
A unit of measure of the rate at which a particle sediments in a centrifugal field.
Swart′s Reagent
Alternative name for Antimony Trifluoride.
Sylvic Acid
Another name for Abietic Acid.
Sylvine
Naturally occuring potassium chloride.
Syneresis
The shrinking of a gel.
Syngas
A gas mixture that contains varying amounts of carbon monoxide and hydrogen generated by the gasification of a carbon containing fuel to a gaseous product with a heating value.
Synthesis
The construction of a compound by the union of elements or simple compounds.
Synthetic
A substance manufactured by chemical synthesis.
TAEE
Abbreviation of Tertiary Amyl Ethyl Ether.
TAME
Abbreviation of Tertiary Amyl Methyl Ether.
Tantalum
A shiny, silvery coloured metal which is heavy, dense, malleable and ductile when pure. It is found in small quantities in minerals.
Tar
A mixture of hydrocarbon oils.
Tautomer
A structure formed by facile motion of a hydrogen from one site to another within the same molecule.
Technetium
A radioactive element not found in ores.
Teflon
Tradename for Polytetrafluoroethylene.
Tellane
Old name for Hydrogen I Telluride.
Tellurium
A rare, silvery-white, semi-metallic element which exhibits both metallic and non-metallic traits.
Temporary Water Hardness
The component of total water hardness that can be removed by boiling the water.
Teratogen
A substance that can cause deformities in embryos. Dioxin is a teratogen.
Terbium
Used in the semiconductor industry as a dopant.
Terminal
A point at which electrical connections can easily be made or broken.
Terminal Reaction
A reaction that ends a cycle or chain of other chemical reactions.
Terpolymer
A copolymer composed of three different types of monomers.
Tertiary Amyl Ethyl Ether
An ether based on reactive C5 olefins and ethanol.

Tertiary Amyl Methyl Ether
An ether based on reactive C5 olefins and methanol.

Tetrachloromethane
Alternative name for Carbon Tetrachloride.
Tetraethyl Germanium

C8H20Ge

An organogermanium compound used in vapour deposition of germanium.

Tetraethyl Lead
An octane enhancer.
Tetraethyl Tin

C8H20Sn

An important example of an organotin compound.

Tetrafluoromethane

CF4

Colourless and odourless gas, used in circuit board manufacture, manufacture of insulating materials and semiconductors. Also used as a low temperature refrigerant.

Tetrahedral
A molecular shape that results when there are four bonds and no lone pairs around the central atom in the molecule.
Tetramethyl Lead

C4H12Pb

Colourless liquid,

Tetramethyl Tin

C4H12Sn

One of the simplest organotin compounds, is useful for transition-metal mediated conversion of acid chlorides to methyl ketones and aryl halides to aryl methyl ketones.

Thallium
A soft, silvery-grey, reactive metal which is only found as a minor constituent of various minerals.
Theoretical Density
This is the density of a material calculated from the atomic weight and crystal structure.
Theoretical Yield
The amount of product obtained when all of the limiting reagent reacts.
Thermalox
Alternative name for Beryllium Oxide.
Thermite Process
The method of obtaining liquid metal by reduction of the oxide with aluminium powder.
Thermochemical Equation
An equation representing a chemical reaction that describes both the stoichiometry and the energetics of the reaction.
Thermochemistry
The study of heat absorbed or released during chemical changes.
Thermodynamics
The study of energy transfers and transformations.
Thermometer
An instrument for measuring temperature.
Thermoplastic
A polymer that softens or melts on heating, and becomes rigid again on cooling.
Thermosetting Plastic
A polymer that solidifies on heating and cannot be remelted.
Thin Layer Chromatography
A technique for separating components in a mixture on the basis of their differing polarities.
Thio-
A prefix that means, replace an oxygen with sulphur.
Thiokol
The trade name of a synthetic rubber, derived from sodium tetrasulphide and organic dichlorides.
Third Ionization Energy
Energy required to remove an electron from an isolated +2 ion.
Thixotropic Fluid
A liquid that becomes less viscous when stirred.
Thorium
Thorium is used as an alternative reactor fuel to uranium, thorium being converted readily into uranium in the reactor.
Thulium
A metallic element that is a member of the rare earth group.
TiAl
Chemical formula for Titanium Aluminide.
TiB2
Chemical formula for Titanium Diboride.
TiC
Chemical formula for Titanium Carbide.
TiCl2
Chemical formula for Titanium II Chloride.
TiCl3
Chemical formula for Titanium III Chloride.
TiF3
Chemical formula for Titanium III Fluoride.
TiF4
Chemical formula for Titanium IV Fluoride.
TiH2
Chemical formula for Titanium Hydride.
Timeline
A brief overview of the major milestones in science and engineering.
Tin
A relatively common element. Tin is a silvery white metal which is soft and pliable, and which emits the characteristic sound of tin cry when bent.
Tin II Chloride

SnCl2

Widely used as a reducing agent, and in electrolytic baths for tin-plating.

Tin II Fluoride

SnF2

White crystalline solid. Old name is Stannous Fluoride.

Tin II Oxide

SnO

Blue-black crystalline solid, also known as Stannous Oxide.

Tin IV Fluoride

SnF4

White crystalline solid. Old name is Stannic Fluoride.

Tin IV Hydride

SnH4

Colourless gas, also known as Stannane.

Tin IV Oxide

SnO2

White or grey crystalline solid. The fully oxidized state of tin metal.

Tin Tetramethyl
Alternative name for Tetramethyl Tin.
TiN
Chemical formula for Titanium Nitride.
Tin-doped Indium Oxide
Alternative name for Indium Tin Oxide.
Tinite
Alternative name for Titanium Nitride.
Tinstone
Another name for Cassiterite, a dark coloured mineral that is an important ore of Tin.
TiO
Chemical formula for Titanium II Oxide.
TiS
Chemical formula for Titanium II Sulphide.
Titanium
Titanium and its alloys are characterised by their lightness, strength and corrosion resistance and are used widely in aerospace applications.
Titanium Aluminide

TiAl

An intermetallic chemical compund that is lightweight and resistant to oxidation.

Titanium Carbide

TiC

Extremely hard material similar to Tungsten Carbide.

Titanium Diboride

TiB2

Extremely hard ceramic compound with excellent resistance to mechanical wear.

Titanium Dioxide

TiO2

Predominantly used as a white pigment.

Titanium Hydride

TiH2

Highly reactive and must be kept away from heat and strong oxidisers.

Titanium II Chloride

TiCl2

Black solid that is a strong reducing agent.

Titanium II Oxide

TiO

Bronze crystals.

Titanium II Sulphide

TiS

Forms brown hexagonal crystals.

Titanium III Chloride

TiCl3

One of the most common halides of titanium and is an important catalyst for the manufacture of polyolefins.

Titanium III Fluoride

TiF3

Violet to purple-red powder.

Titanium IV Fluoride

TiF4

White powder that is hygroscopic.

Titanium Monosulphide
Alternative name for Titanium II Sulphide.
Titanium Monoxide
Alternative name for Titanium II Oxide.
Titanium Nitride

TiN

Extremely hard ceramic used as a coating to improve surface properties.

Titanium Tetrafluoride
Alternative name for Titanium IV Fluoride.
Titanium Trichloride
Alternative name for Titanium III Chloride.
Titanium Trifluoride
Alternative name for Titanium III Fluoride.
Titanous Chloride
Alternative name for Titanium III Chloride.
Titrant
The substance that quantitatively reacts with the analyte in a titration.
Titration Curve
A plot that summarizes data collected in a titration.
TNT
Abbreviation of the explosive Trinitrotoluene.
Toluene
Also known as methylbenzene or toluol it is used as a solvent and as an intermediate for its derivatives.
Toluol
Also known as toluene.
Tombac
A brass alloy 88% copper and 12% zinc.

Total Hydrocarbons
All of the hydrocarbon emissions from an internal combustion engine.
Touchstone
A touchstone is a device for roughly ascertaining the purity of gold alloys.
Toxic Emission
Any pollutant emitted from a source that can negatively affect human health or the environment.
Toxicology
The study of poisons, including identification, isolation, biological effects, mechanism of action, and development of antidotes.
Transformation Rate
The reciprocal of the time necessary for a reaction to proceed halfway to its completion.
Transgranular
Through or across crystals or grains.
Transition Metal
An element with an incomplete d subshell.
Transmutation
A process of converting one element to another by irradiating or bombarding it with radioactive particles.
Transuranic
A chemical term referring to artificially manufactured elements which have an atomic number higher than uranium.
Triacontane

C30H62

Long chain Alkane that is a solid at room temperature.

Trichlorethene

C2HCl3

A solvent and dry cleaning fluid.

Trichloroethylene
Another name for Trichlorethene.
Trichlorofluoromethane

CCl3F

A colourless, nearly odorless liquid that boils at about room temperature. This was the first widely used refrigerant.

Trichlorogallane
Alternative name for Gallium III Chloride.
Trichlorogallium
Alternative name for Gallium III Chloride.
Trichloromethane
Another name for Chloroform.
Trichlorostibine
Alternative name for Antimony Trichloride.
Trifluoroantimony
Alternative name for Antimony Trifluoride.
Triglyceride
An ester of glycerol and three fatty acids.
Trigonal Bipyramidal
A molecular shape that results when there are five bonds and no lone pairs on the central atom in the molecule.
Trigonal Planar
A molecular shape that results when there are three bonds and no lone pairs around the central atom in the molecule.
Trigonal Pyramidal
A molecular shape that results when there are three bonds and one lone pair on the central atom in the molecule.
Trilene
Trade name for Trichlorethene.
Trilithium Nitride
Old name for Lithium I Nitride.
Trinitrotoluene
Used as a high explosive and known as TNT.

Trioxide
A compound with three atoms of oxygen with an element or radical.
Triple Bond
A covalent bond that involves 3 bonding pairs.
Tritium
A radioisotope of hydrogen with two neutrons and one proton in its nucleus.
Triton
Nucleus of a tritium atom.
Tugarinovite
Alternative name for Molybdenum IV Oxide.
Tumbaga
An alloy composed mostly of gold and copper that has a significantly lower melting point than gold or copper alone.

Tungsten
A metallic element that is lustrous and silvery white in colour, and does not occur naturally.
Turbidity
The degree of clearness of a liquid or the lack of visual clarity of a liquid.
Turnbull′s Blue
Turnbull′s Blue is a pigment produced by the action of a ferrous salt on potassium ferri-cyanide.
Turpentine
A solvent for lacquers and polishes obtained by the steam distillation of rosin.
Tutty
An old name for oxygen.
Twin Bands
Bands across a crystal grain where crystallographic orientations have a mirror image relationship to the orientation of the matrix grain across a composition plane usually parallel to the sides of the band.
Tyrian Dye
A purple dye derived from animal juice in the shell-fish murex.
UF4
Chemical formula for Uranium IV Fluoride.
Ultramarine
A blue pigment derived from lapis lazuli.
Umber
A brown pigment comprised of hydrated ferric and manganese oxides with variable proportions of earthy matter.
Undecane

C11H24

A liquid alkane hydrocarbon that is used as a mild sex attractant for various types of moths and cockroaches.

Unimolecular Reaction
A reaction that involves isomerization or decomposition of a single molecule.
Unit
A standard for comparison in measurements. For example, the metre is a standard length which may be compared to any object to describe its length.
Unit Cell
The smallest repetitive volume that comprises the complete pattern of a crystal.
Units
Lists all Units topics in the Encyclopaedia
Universal Indicator
A universal indicator is an indicator which undergoes several colour changes over a wide range of pH.
Unnilhexium
Element with an atomic number of 106.
Unnilpentium
Element with an atomic number of 105.
Unnilquadium
An element with an atomic number of 104.
Unnilseptium
An element with an atomic number of 107.
Unpaired Electron
A single electron occupying an orbital.
Unsaturated Compounds
Organic compounds containing double or triple bonds capable of forming addition products.
Unsaturated Solution
A solution with a concentration lower than its equilibrium solubility.
Unstable
Characteristic of a structure that collapses or deforms under a realistic load or a chemical that decomposes.
UO2
Chemical formula for Uranium Oxide.
Uraninite
Naturally occuring Uranium Oxide.
Uranium
Although uranium is the longest known member of the actinide group of metals, it attracted scant attention until the discovery of uranium fission in 1939.
Uranium IV Fluoride

UF4

Green crystalline solid compound of uranium with an insignificant vapour pressure and very slight solubility in water.

Uranium Oxide

UO2

Greyish-black brittle and heavy mineral.

Urea
Common name for Carboxamide.
Urea Formaldehyde
A non-transparent thermosetting resin or plastic, made from urea and formaldehyde heated in the presence of a mild base such as ammonia or pyridine.

Urea Methanal
Another name for Urea Formaldehyde.
Used Oil
Any oil that has been in a piece of equipment, whether operated or not.
Vacancy
An unfilled lattice site in a crystal structure.
Vacuum Distillation
A distillation method which involves reducing the pressure above a liquid mixture to be distilled to less than its vapour pressure.
Valence
The charge on an ion based on the number of electrons transferred or shared within a specific structure.
Valence Bond
In the valence bond theory, a valence bond is a chemical bond formed by overlap of half-filled atomic orbitals on two different atoms.
Valence Electrons
The electrons in the outermost shell of an atom.
Valence Shell
The electrons in the outermost shell of an atom.
Valence Shell Electron Pair Repulsion Theory
A model that explains the shapes of molecules by assuming that electron pairs arrange themselves around atoms in a way that minimizes electron-electron repulsions.
van der Waals Bond
A secondary interatomic bond between adjacent molecular dipoles, which may be permanent or induced.
Vanadium
The principal use for vanadium is as an alloying constituent, particularly in steels where it is introduced as ferrovanadium, an alloy of iron and vanadium.
Vapour
A gas whose temperature is below its critical temperature, so that it can be condensed to the liquid or solid state by increase of pressure alone.
Varnish
A resin in solution.
Venetian Red
A permanent red pigment composed of ferric oxide and obtained by igniting ferrous sulphate.
Verdigris
A mixture of acetates of copper used in making some green pigments.
Vermilion
Mercury Sulphide, used as a red pigment, also known as cinnabar.
Vinyl Acetate

C4H6O2

A colourless liquid with a pungent odor, it is the precursor to polyvinyl acetate, an important polymer in industry.

Vinyl Benzene
Another name for Styrene.
Vinylcyanide
Alternative name for Acrylonitrile.
Vinylethylene
Another name for 1,3-Butadiene.
Vinylformic Acid
Alternative name for Acrylic Acid.
Virenium
An alloy with 81% Copper, 10% Zinc and 9% Nickel. A German Silver type of alloy containing nickel as well as copper and zinc with a magnetic element as a built in security device.

Vital Air
An old name for oxygen
Vitamin
A substance that is critical for proper functioning of a living organism that the organism is unable to produce in sufficient quantities for itself.
Vitiated Air
Air from which oxygen has been removed, thus mainly nitrogen.
Vitreous Enamel
An opaque or transparent glaze, generally coloured, which adheres to a suitable metallic surface when applied in a liquid state.
Vitreous Silica
The glassy isotropic form of quartz.
Vitrifying Tendency
Tendency of the crystalline phase of a ceramic to transform into an amorphous or glassy phase when subjected to aging or temperature cycling.
VOC
Abbreviation of Volatile Organic Compound.
Volatile
A solid or liquid material that easily vaporizes. A material with a significant vapour pressure.
Volatile Organic Compound
Organic chemicals and petrochemicals that emit vapours.
Volemitol

C7H16O7

Naturally occurring seven-carbon sugar alcohol. It is a substance widely distributed in plants, red algae, fungi, mosses, and lichens.

Voltaic Cell
Or more commonly known as a battery.
Voltaic Pile
An early battery consisting of disks of dissimilar metals (usually zinc and copper) separated by moist paper or cloth soaked in an electrolyte solution.
Volume Percentage
The concentration of a component in a mixture or an element in a compound.
Vulcanization
A process of combining rubber with sulphur or other substances.
Waste Water
The used water and solids from industrial processes that flow to a treatment plant.
Water
A colourless, tasteless liquid with some very peculiar properties that stem from the bent H-O-H structure of its molecules.
Water Absorption
A materials tendency or lack of to absorb water.
Water Gas
A fuel gas used in industrial synthesis of organic chemicals, and in welding, glassmaking, and other high-temperature industrial applications.

Water Glass
Old name for Sodium Silicate.
Water Hardness
Water contaminated with compounds of calcium and magnesium.
Water of Crystallization
Water present in the crystal of a hydrate.
Water of Rabel
A solution of ethyl ether in ethanol.
Water Softener
A device or system used to remove calcium and magnesium hardness minerals from a water supply.
Wax
Esters of monohydric alcohols.
Weak Ligand
A ligand that causes a small crystal field splitting which results in a high-spin complex.
Weathering
The action of wind, temperature changes, chemicals and water that breaks the surface of rocks into smaller particles.
Weight Percent
To calculate the mass percent or weight percent of a solution, you must divide the mass of the solute by the mass of the solution (both the solute and the solvent).
Wetting
Covering with a surface with thin film of liquid.
Wetting Agent
A surface-active agent that promotes wetting by decreasing the cohesion within a liquid.
White Calx of Antimony
Mixture of antimony oxide and potassium oxide.
White Cast Iron
A low-silicon and very brittle cast iron, in which the carbon is in combined form as cementite; a fractured surface appears white.

White Gold
An alloy of gold and nickel or palladium used in jewellery.

White Lead
Old name for Lead II Carbonate.
White Metal
The name given to a range of alloys usually containing antimony alloyed with tin, copper or lead to produce a white silvery metal.
White Spirit
A petroleum distillate that is often used as a cheap substitute for turpentine.
White Vitriol
Old name for Zinc Sulphate.
Wismuth
Ancient name for Bismuth.
Witherite
Another name for Barium Carbonate.
Wolfram
The old name for Tungsten and from where the chemical symbol W was derived.
Wood
A hard substance which forms the branches and trunks of trees and which can be used as a building material, for making things, or as a fuel.
Wood Alcohol
Another name for Methyl Alcohol.
Wood Ether
Alternative name for Dimethyl Ether.
Woodward-Hoffmann Rules
Rules governing the formation of products during certain types of organic reactions.
Wool
Specifically sheep covering.
Woulfe Bottle
A bottle with two or more necked orifices that was used in distillation.
Xanthophyll
A class of oxygen-containing carotenoid pigments.
Xenon
One of the rare gases formed as a result of radioactive decay of uranium fission fragments.
X-Ray Crystallography
Determination of three dimensional arrangement of atoms in a crystal by analysis of x-ray diffraction patterns.
X-Ray Diffraction Pattern
Interference patterns created by x-rays as they pass through a solid material.
X-Ray Spectrum
A set of characteristic x-ray frequencies or wavelengths produced by a substance used as a target in an x-ray tube.
Xylene
An aromatic hydrocarbon derived from petroleum and used to increase octane.

Xylitol

C5H12O5

Naturally found in low concentrations in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse and birch.

Xylol
A commercial preparation of xylenes (alternatively known as dimethylbenzenes).
Yield
The amount of product actually obtained in a chemical reaction.
Yperite
Common name for Dichlorodiethyl Sulphide or mustard gas.
Ytterbium
A soft, silvery-white metal of the lanthanide group
Yttrium
A lanthanide group metal found in most rare earth minerals.
Zeolite
A natural mineral that has the capacity to absorb hardness, calcium, and magnesium ions from water.
Zeolite Softening
Refers to the process, where zeolite chemicals are capable to exchange ions with the hardness causing impurities of the water.
Zero Order Reaction
A reaction with a reaction rate that does not change when reactant concentrations change.
Zero Point Energy
A minimum possible energy for an atom or molecule predicted by quantum mechanics.
Zinc
Used as a galvanic coating on steel to prevent corrosion and is used as a constituent of various alloy systems.
Zinc Blende
An old name for Zinc Sulphide.
Zinc Chloride

ZnCl2

A white crystalline compound.

Zinc Chromate
Bright yellow pigment which chemically is substantially zinc chromate, although its precise composition is rather complex. Its chief use is in anti-corrosive paints and primers for steel.

Zinc Nitrate

Zn(NO3)2

Used as a mordant in dyeing and also a source of zinc ions for chemistry.

Zinc Oxide

ZnO

Used as a constituent of creams for its soothing qualities.

Zinc Phosphate

Zn3(PO4)2

Used as a corrosion resistant coating on metal surfaces either as part of an electroplating process or applied as a primer pigment.

Zinc Plating
The application of a zinc coating by galvanizing or electrogalvanizing.
Zinc Sulphate

ZnSO4

Water soluble.

Zinc Sulphide

ZnS

The commenest zinc ore, known as Sphalerite or Zinc Blende.

Zincography
Process of etching unprotected parts of a zinc plate with strong acids to produce a printing surface.
Zingiberene

C15H24

Monocyclic sesquiterpene that is the predominant constituent of the oil of ginger.

Zirconium
The metal is extremely corrosion resistant due to the formation of a stable oxide film.
Zirconium Oxide
Used in enamels and ceramic coatings.

ZnCl2
Chemical formula for Zinc Chloride.
ZnO
Chemical formula for Zinc Oxide.
ZnS
Chemical formula for Zinc Sulphide.
ZnSO4
Chemical formula for Zinc Sulphate.
Zone
Any group of crystal planes that are all parallel to one line, called the zone axis.
Zone Refining
A technique used to reduce the level of impurities in certain metals, alloys, semiconductors, and other materials.
ZrO
Chemical formula for Zirconium Oxide.
Zwitterion
A particle that contains both positively charged and negatively charged groups.
Zymase
Enzymes present in yeast that catalyze fermentation of sugar into alcohol and carbon dioxide.
Zymogen
An inactive precursor of an enzyme.

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