Tungsten, also known as wolfram, is a chemical element with the chemical symbol W and atomic number 74. Tungsten word comes from the Swedish language directly translatable tung sten heavy stone, so it is commonly called volfram Swedish.
A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth as in chemical compounds. He was identified as a new element in 1781, and first isolated in 1783 as a metal. Its important minerals are wolframite and scheelite. The free element is remarkable for its strength, particularly the fact that it has a melting point of the highest of all metals and non-allies, the second highest of all the elements after carbon. Equally remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than lead. Tungsten with minor amounts of impurities is often brittle and hard, making it difficult to work. However, pure tungsten, but still difficult, is more ductile, and can be cut with a hacksaw hard steel.
The unalloyed elemental form is used mainly in electrical applications. Many tungsten alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (as both the filament and target), TIG welding electrodes and superalloys. The hardness of tungsten and high density to give military applications in penetrating projectiles. Tungsten compounds are most often used in industry as catalysts.
Tungsten is the only metal from the third transition series that is known to occur in biomolecules, where it is used in some species of bacteria. It is the heaviest element known to be used by any living organism. Tungsten and molybdenum interfere with copper metabolism, and is slightly toxic to animal life.
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