Tantalum

TANTALUM, Ta, chemical element of group V of the periodic system. Atomic weight 181.4; atomic number 73. Compounds of T. can be trivalent and pentavalent. In nature it is found in the form of tantalites, e.g. Fe(TaO₃)₂. The main deposits of tantalites are Finland, Scandinavia, USA, Australia. T. is a metal of gray color; specific weight 16.7, melting point 2,800°, boiling point 4,400°. T. when heated in the air oxidizes at 400°, and at 700° burns completely to Ta₂O₅. T. is easily subjected to mechanical processing: forging, rolling. Alloys of T. with iron are extremely chemically stable, due to which they can sometimes even replace platinum. It is used in industry for the manufacture of electrodes for electronic lamps, chemical apparatus, dental instruments, "everlasting" pens, etc. It has no biological, pharmacological or toxicological significance, but is used in the preparation of X-ray tubes, for dental and surgical instruments, for the manufacture of incandescent electric lamps and for current rectifiers.