Tantalum Basic Facts
Atomic Number: 73
Atomic Weight: 180.9479
Discovery: Anders Ekeberg 1802 (Sweden), showed that niobic acid and tantalic acid were two different substances.
Electron Configuration: Xe 6s2 4f14 5d3
Word Origin: Greek Tantalos, mythological character, king who was father of Niobe
Isotopes: There are 25 known isotopes of tantalum. Natural tantalum consists of 2 isotopes.
Properties: Tantalum is a heavy, hard gray metal. Pure tantalum is ductile and may be drawn into very fine wire. Tantalum is practically immune to chemical attack at temperatures lower than 150 °C. It is only attacked by hydrofluoric acid, acidic solutions of the fluoride ion, and free sulfur trioxide. Alkalis attack tantalum very slowly. At higher temperatures, tantalum is more reactive. The melting point of tantalum is very high, exceeded only by that of tungsten and rhenium. The melting point of tantalum is 2996 °C; boiling point is 5425 +/- 100 °C; specific gravity is 16.654; valence is usually 5, but may be 2, 3, or 4.
Uses: Tantalum wire is used as a filament for evaporating other metals. Tantalum is incorporated into a variety of alloys, conferring high melting point, ductility, strength, and corrosion resistance. Tantalum carbide is one of the hardest materials ever made. At high temperatures, tantalum has good 'gettering' ability. Tantalum oxide films are stable, with desirable dielectric and rectifying properties. The metal is used in chemical process equipment, vacuum furnaces, capacitors, nuclear reactors, and aircraft parts. Tantalum oxide may be used to make a glass with a high index of refraction, with applications including use for camera lenses. Tantalum is immune to body liquids and is a non-irritating metal. Therefore, it has widespread surgical applications.
Sources: Tantalum is found primarily in the mineral columbite-tantalite (Fe, Mn)(Nb, Ta)2O6. Tantalum ores are found in Australia, Zaire, Brazil, Mozambique, Thailand, Portugal, Nigeria, and Canada. A complicated process is required to remove tantalum from the ore.
Element Classification: Transition Metal
Tantalum Physical Data
Density (g/cc): 16.654
Melting Point (K): 3269
Boiling Point (K): 5698
Appearance: heavy, hard gray metal
Atomic Radius (pm): 149
Atomic Volume (cc/mol): 10.9
Covalent Radius (pm): 134
Ionic Radius: 68 (+5e)
Specific Heat (@20°C J/g mol): 0.140
Fusion Heat (kJ/mol): 24.7
Evaporation Heat (kJ/mol): 758
Debye Temperature (K): 225.00
Pauling Negativity Number: 1.5
First Ionizing Energy (kJ/mol): 760.1
Oxidation States: 5
Lattice Structure: Body-Centered Cubic
Lattice Constant (Å): 3.310
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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