Tungsten (W)

Pure tungsten is a steel-gray to tin-white metal. Very pure tungsten can be cut with a hacksaw, forged, spun, drawn, and extruded. The impure metal is brittle and can be worked only with difficulty. Tungsten has the highest melting point of all metals, and at temperatures over 1650°C has the highest tensile strength. The metal oxidizes in air and must be protected at elevated temperatures. It has excellent corrosion resistance and is attacked only slightly by most mineral acids. The thermal expansion is about the same as borosilicate glass, which makes the metal useful for glass-to-metal seals.

The name derives from the Swedish tungsten for "heavy stone". The symbol W derives from the German wolfram, which was found with tin and interfered with the smelting of tin. It was said to eat up tin like a wolf eats up sheep. The element was discovered by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1781. Tungsten metal was first isolated by the Spanish chemists Fausto Elhuyar and his brother Juan José in 1783.

Tungsten was discovered by Juan José and Fausto Elhuyar, Spanish chemists and brothers, in 1783 in samples of the mineral wolframite ((Fe, Mn)WO4). Today, tungsten is primarily obtained from wolframite and scheelite (CaWO4) using the same basic method developed by José and Elhuyar. Tungsten ores are crushed, cleaned and treated with alkalis to form tungsten trioxide (WO3). Tungsten trioxide is then heated with carbon or hydrogen gas (H2), forming tungsten metal and carbon dioxide (CO2) or tungsten metal and water vapor (H2O).

From Swedish, tung sten meanig heavy stone. In 1779 Peter Woulfe examined the mineral now known as wolframite and concluded it must contain a new substance. Scheele, in 1781, found that a new acid could be made from tungsten (a name first applied about 1758 to a mineral now known as scheelite). Scheele and Berman suggested the possibility of obtaining a new metal by reducing this acid. The de Elhuyar brothers found acid in wolframite in 1783 that was identical to the acid of tungsten (tungstic acid) of Scheele, and in that year they succeeded in obtaining the element by reduction of this acid with charcoal. Tungsten occurs in wolframite, scheelite, huebnertie, and ferberite. Important deposits of tungsten occur in California, Colorado, South Korea, Bolivia, Russia, and Portugal. China is reported to have about 75% of the world's tungsten resources. Natural tungsten contains five stable isotopes. Twenty one other unstable isotopes are recognized. The metal is obtained commercially be reducing tungsten oxide with hydrogen or carbon.