Home - Periodic Tables
(Gr. Tantalos, mythological character, father of Niobe) Discovered in 1802 by Ekeberg,
but many chemists thought niobium and tantalum were identical elements until Rowe in 1844,
and Marignac, in 1866, showed that niobic and tantalic acids were two different acids. The
early investigators only isolated the impure metal. The first relatively pure ductile
tantalum was produced by von Bolton in 1903. Tantalum occurs principally in the mineral
Tantalum ores are found in Australia, Brazil, Mozambique, Thailand, Portugal, Nigeria,
Zaire, and Canada.
Separation of tantalum from niobium requires several complicated steps. Several methods
are used to commercially produce the element, including electrolysis of molten potassium
fluorotantalate, reduction of potassium fluorotantalate with sodium, or reacting tantalum
carbide with tantalum oxide. Twenty five isotopes of tantalum are known to exist. Natural
tantalum contains two isotopes.
Tantalum is a gray, heavy, and very hard metal. When pure, it is ductile and can be
drawn into fine wire, which is used as a filament for evaporating metals such as aluminum.
Tantalum is almost completely immune to chemical attack at temperatures below 150oC, and is attacked only by
hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide.
Alkalis attack it only slowly. At high temperatures, tantalum becomes much more reactive.
The element has a melting point exceeded only by tungsten and rhenium. Tantalum is used to
make a variety of alloys with desirable properties such as high melting point, high
strength, good ductility, etc. Tantalum has a good "gettering" ability at high
temperatures, and tantalum oxide films are stable and have good rectifying and dielectric
Scientists at Los Alamos have produced a tantalum carbide graphite composite material,
which is said to be one of the hardest materials ever made. The compound has a melting
point of 3738oC. Tantalum
is used to make electrolytic capacitors and vacuum furnace parts, which account for about
60% of its use. The metal is also widely used to fabricate chemical process equipment,
nuclear reactors, aircraft, and missile parts. Tantalum is completely immune to body
liquids and is a nonirritating material. It has, therefore, found wide use in making
surgical appliances. Tantalum oxide is used to make special glass with high index of
refraction for camera lenses. The metal has many other uses.
The price of (99.9%) tantalum in Dec. 1988 was about $50/oz.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
[an error occurred while processing this directive]