Tungsten

Tungsten is a chemical element with the symbol W and atomic number 74. The name tungsten comes from the former Swedish name for the tungstate mineral scheelite, tung sten or "heavy stone". Tungsten is a rare metal found naturally on Earth almost exclusively combined with other elements in chemical compounds rather than alone. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include wolframite and scheelite.

Characteristics

Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. Tungsten's hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are also often used as industrial catalysts.

Occurrence

Tungsten is the 59th most abundant element in the Earth's crust and is nearly always found in chemical combination. It is about as abundant as tin or lead.

History

The element was discovered by the Swedish chemist Carl Wilhelm Scheele in 1781. Tungsten was first isolated as a metal in 1783 by the Spanish chemists Juan José Elhuyar and Fausto Elhuyar.

Applications

The most common use of tungsten is in bulb and tube filaments and electrodes, as well as in wear-resistant tools and alloys. Tungsten carbide (WC or W2C) is an extremely hard tungsten compound. It is used in the tips of drill bits, high speed cutting tools and in mining machinery.

Biological role

Tungsten is used in enzymes in a few species of bacteria, but is not known to be used by any higher organisms. Tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to animal life.

Precautions

Tungsten compounds should be handled with care. The metal dust presents a fire hazard in the workshop. Tungsten is considered to be of low toxicity.

See also

• List of chemical elements
• Periodic table

Tungsten Resources
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