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Tungsten (pronounced), also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74. Tungsten is as known the heaviest materials except gold of the nature resources, for the density of tungsten is 19.25 g•cm−3(near r.t.). For the same reason, tungsten related products, alloys(Nickel-Copper-Ferro Binder), other elements doped(Al-doped, Th-doped, La-dope, Ce-dopd and K-doped) and carbides( carbonized tungsten powder with cobalt or Nickel binder) have the special ccharacteristics as pure tungsten, then it always named heavy stone.
Tungsten is a typiacl element of transition element Group VI and shows oxidation states from +6 to-2 and, particularly in its oxides, forms many non-stoicheiometric compounds. There is little aqueous chemistry except that of complex oxy-anions and some complex halides. The hexahalides are moleular but lower halides are polymeric and the lowest halides show extensive W-W bonding (more than Mo). Carbonyl and phos-phine derivatives are typical low oxidation state compounds. Complexes are formed, particularly by O-and S-ligands in higher oxidation states and by P-ligands in low oxidation states. Complex cyanides are well established.
Tungsten is one of Nonferrous Metals, and also it is as molybdenum and rare earth which are Refractory Metals, in the modern industrial time, it is the most important Strategic Metals for IT industrial and military industrial.
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