Tungsten or Wolfram
| Number: | 74 |
| Symbol: | W |
| Atomic Weight: | 183.85 |
| Discovery: | J. and F. d'Elhuyar purified tungsten in 1783, although Peter Woulfe examined the mineral which came to be known as wolframite and determined that it contained a new substance. |
| Electron Configuration: | [Xe]6s24f145d4 |
| Word Origin: | Swedish tung sten, heavy stone or wolf rahm and spumi lupi, because the ore wolframite interfered with tin smelting and was believed to devour the tin. |
| Isotopes: | Natural tungsten consist of five stable isotopes. Twelve unstable isotopes are known. |
| Properties: | Tungsten has a melting point of 3410+/-20°C, boiling point of 5660°C, specific gravity of 19.3 (20°C), with a valence of 2, 3, 4, 5, or 6. Tungsten is a steel-gray to tin-white metal. Impure tungsten metal is quite brittle, although pure tungsten can be cut with a saw, spun, drawn, forged, and extruded. Tungsten has the highest melting point and the lowest vapor pressure of the metals. At temperatures exceeding 1650°C, it has the highest tensile strength. Tungsten oxidizes in air at elevated temperatures, although it generally has excellent corrosion resistance and is minimally attacked by most acids. |
| Uses: | The thermal expansion of tungsten is similar to that of borosilicate glass, so the metal is used for glass/metal seals. Tungsten and its alloys are used to make filaments for electric lamps and television tubes, as electrical contacts, x-ray targets, heating elements, for metal evaporation components, and for numerous other high temperature applications. Hastelloy, Stellite, high-speed tool steel, and numerous other alloys contain tungsten. Magnesium and calcium tungstenates are used in fluorescent lighting. Tungsten carbide is important in the mining, metalworking, and petroleum industries. Tungsten disulfide is used as a dry high-temperature lubricant. Tungsten bronze and other tungsten compounds are used in paints. |
| Sources: | Tungsten occurs in wolframite, (Fe, Mn)WO4, scheelite, CaWO4, ferberite, FeWO4, and huebnerite, MnWO4. Tungsten is produced commercially by reducing tungsten oxide with carbon or hydrogen. |
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