Tantalum
Tantalum is a metal element denoted by the atomic symbol Ta. It has an atomic number of 73, and the average atomic weight of its two naturally occurring isotopes is 180.9479. It is a very hard, heavy, grey metal that is malleable and ductile. It has one of the highest melting points of any element at 5462.6°F (3017°C). At temperatures of less than 302°F (150°C), it is very unreactive and is attacked only by hydrofluoric acid and its acid salts and by sulfur trioxide. It is much more reactive at higher temperatures.
In 1802, the Swedish chemist and mineralogist Anders Gustaf Ekeberg (1767-1813) discovered tantalum in two minerals, tantalite, from Finland, and yttrotantalite, from Sweden. The name tantalum comes from the Greek mythological character, Tantalos, father of Niobe.
Questions were raised almost immediately as to whether the new element was really such or whether it was identical with niobium, which had been discovered a year earlier. The great English chemist W. H. Wollaston analyzed both materials and concluded that they were identical. Wollaston's view was accepted by chemists for nearly half a century. Then, in 1844, the German chemist Heinrich (1795-1864) reopened the debate and eventually showed that niobium and tantalum really are different from each other.
The confusion between the two elements is not difficult to understand. They always occur together and are extremely difficult to separate from each other. A pure sample of tantalum metal was not produced until the German chemist Werner von Bolton did so in 1903.
Tantalum is found in nature as part of the mineral columbite-tantalite. It is found throughout the world in places such as Australia, Brazil, Nigeria and Canada. It is purified commercially by electrolysis or by a reduction process with potassium fluorotantalate and sodium.
Alloys of tantalum reflect the metal's properties and tend to have high melting points, great strength, and good ductility. They are used in making pen points, analytical weights, and laboratory equipment for chemistry, medicine, and dentistry. Because tantalum is so chemically inert, and because it causes no reactions in body tissue, it is increasingly used in making prosthetic devices such as artificial hips and knees. Compounds of tantalum such as tantalum oxide are used for making camera lenses. Other compounds are used as catalysts, electrolytic capacitors, and vacuum furnace parts.
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