Tantalum

Tantalum is a shiny, silvery coloured metal which is heavy, dense, malleable and ductile when pure. It is found in small quantities in minerals (generally in conjunction with niobium), and is isolated by conversion to the oxide and then the fluoro-complex, K2 TaF7 , from which the pure metal is obtained by electrolysis. Tantalum is extremely corrosion resistant due to the formation of an oxide film, and is also resistant to acid attack (with the exception of HF). It will react with fused alkalis and a variety of non-metals at elevated temperatures. Tantalum can be used as a replacement for platinum for laboratory apparatus which has to have good corrosion resistance, and the metal is also used within the chemical industry for similar reasons. The fluids in the human body do not react with the metal and, hence, it is used for surgical implants without rejection. Other applications include the use of tantalum carbide in cemented carbides which are used as cutting tools. The pure metal is used in the electronics industry in the manufacture of various types of electronic equipment (e.g. rectifiers, capacitors, lamp filaments, etc.). Tantalum is also used in vacuum systems as it has a high absorption rate for residual gases. It is also used as an alloying element with, for example, nickel and molybdenum, to produce alloys which have good corrosion resistance, strength and ductility.


Symbol
Ta

Discovered
1802 by A.G. Ekeberg in Uppsala, Sweden.

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Atomic number 73 Clip
Atomic / Molecular Weight 180.9479 gmol-1Clip
Density 16670 kgm-3Clip
Crystal Structure bcc Clip
Lattice constant 330 fmClip
Melting Point 3273 KClip
Boiling Point 5773 KClip
Linear expansivity 0.0000063 K-1Clip
Specific heat capacity 138 Jkg-1K-1Clip
Thermal conductivity 57 Wm-1K-1Clip
Acoustic wave velocity (longitudinal bulk waves) 4159 ms-1Clip
Acoustic wave velocity (Irrotational waves) 3337 ms-1Clip
Acoustic wave velocity (Shear waves) 2036 ms-1Clip
Acoustic wave velocity (Rayleigh waves) 1902 ms-1Clip
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See also: Periodic Table.

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Subjects: Chemistry