A radioactive element.
Where audio signals increase and decrease the amplitude of the "carrier wave".
Abbreviation of attometre a distance of 10-18m.
The unit of density of a gas at stp equal to 44.614774 molm-3.
An alloy that contains mercury.
The acoustic characteristics of a space with regard to reverberation.
Ambient Environment
The conditions characterizing the air or other medium that surrounds materiel.
Ambient Noise
The composite of airborne sound from many sources near and far associated with a given environment.
Ambient Temperature
The average temperature of the surroundings.
The properties of something that allow it to have more than one possible meaning.
A continuous aisle in a circular building, as in a church.
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.
American National Standards Institute
A private, non-profit organisation that produces industrial standards.
American Petroleum Institute
National trade association that represents all aspects of America’s oil and natural gas industry.
American Society For Testing Material
An open forum for the development of high-quality, market relevant international standards used around the globe.
American Society of Mechanical Engineers
Founded in 1880 as the American Society of Mechanical Engineers, today′s ASME promotes the art, science & practice of mechanical & multidisciplinary engineering and allied sciences around the globe.
American Standard Code for Information Interchange
Coding for text files.
American Standard Pipe Thread
A type of screw or thread, commonly used on pipe fittings to assure a tight seal.
American Welding Society
The mission of the American Welding Society is to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying.
American Wire Gauge
A numbering system for standard wire diameters, often abbreviated as AWG.
A radioactive element. Alpha particle emitter with a half life of 475 years.
Ames Test
A simple bacterial test for carcinogens.
Amicable Numbers
Two numbers are said to be amicable if each is equal to the sum of the proper divisors of the other.
The most stable of all the carbonyl functional groups.
A class of organic compounds in which one or more of the hydrogen atoms of ammonia have been replaced by other groups of atom.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.
Alternative name for Aniline.
Ammann, Othmar Herrmann
Engineer and designer of numerous long suspension bridges, including the Verrazano-Narrows Bridge over New York harbour.
Instrument for measuring the current in amps, milliamps or microamps.
Ammeter Shunt
A low-resistance conductor, placed in parallel with an ammeter movement, so that most of the current flows through the shunt, and only a small portion flows through the ammeter.
A metal ion complex containing ammonia as a ligand.
Obtained from nitrogen using the Haber process and used in the manufacture of fertilizers and explosives.
Ammonium Acetate


Derived from the reaction of ammonia and acetic acid.

Ammonium Bicarbonate


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

Ammonium Carbonate


Ammonium Chloride


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

Ammonium Fluoride


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


Used as a nutrient for the yeast in brewing.

Ammonium Hydroxide
A solution of ammonia in water.
Ammonium Iodide


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


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

Ammonium Sulphate


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

Organisms which excrete excess nitrogen in the form of ammonia.
Amor Asteroids
Have orbits that cross the orbit of Mars and approach Earth′s orbit.
The branch of science concerned with the determination of amorphous solid structures and their systemmatic classification.
Non-crystalline, without long-range order.
Amorphous Semiconductor
A non-crystalline semiconductor material that has no long range order.
Amorphous Solar Cell
These cells are not as efficient as the monocrytalline cells but they do perform better in low light levels.
Amount of Substance
The SI unit of the Amount of Substance is the mole.
The informal name for Ampere.
The amount of current flow within a circuit, expressed in amps.
The SI unit of Electric current.
Ampere Andre Marie
Permanent place in the history of science because it was his name that was given to the unit by which we measure electrical current.
Ampere Hour Capacity
A measurement of storage battery ability to deliver a specified current over a specified length of time.
Ampere Hour Efficiency
The ratio of the output of a secondary cell or battery, measured in ampere-hours, to the input required to restore the initial state of charge, under specified conditions.
Ampere Hour Meter
An instrument that monitors current over time. The indication is the product of current (amperes) and time (hours).
An alternative unit of electrical charge.
Ampere′s Law
The line integral of the magnetic flux around a closed curve is proportional to the algebraic sum of electric currents flowing through that closed curve.
The magnetomotive force developed by 1 ampere of current flowing through a coil of one turn.
Determining the concentration of a material in a sample by measuring electric current.
The character &
A prefix used to name certain members of a series of geometric isomers or stereoisomers.
Amphibolic Pathway
A metabolic pathway used in both catabolism and anabolism.
Containing both polar and nonpolar domains.
Amphiprotic Solvent
Solvents that exhibit both acidic and basic properties.
A substance that can act as either an acid or a base in a reaction.
A special dc generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times produces gain of approximately 10,000.
Amplifiers are used to provide a number of functions.
Amplification Factor
The voltage gain of an amplifier with no load on the output.
A circuit or element that provides gain.
The maximum distance from the equilibrium position that occurs in periodic motion.
Amplitude Distortion
A distortion of the wave shape of a signal.
Amplitude Envelope
The function describing how the maximum amplitude of a waveform evolves over time.
Amplitude Flatness
A measure of how close to constant the gain of a circuit remains over a range of frequencies.
Amplitude Modulation
Where audio signals increase and decrease the amplitude of the "carrier wave".
Amplitude Stability
The ability of the oscillator to maintain a constant amplitude in the output waveform.
Defined as one twelfth of the mass of the most abundant isotope of carbon (12C)
Amyl Alcohol
The IUPAC name for Butanol.
Amyl Nitrite


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.

A form of starch made of glucose molecules linked in a branching pattern.
A form of starch made of long, unbranched chains of -D-glucose molecules.
Another name for starch.