William:
Here is some more info on tungsten:
Atomic Symbol: W
Atomic Weight: 183.85
Electron Configuration: -32-12-2
History:
(Swedish, tung sten, 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 in 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 recucing tungsten oxide with
hydrogen or carbon. Pure tungsten is a stelel-gray to tin-white metal. Very pure tungsten
can be cut with a hacksaw, and can be 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 1650C 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. tungsten and its alloys are used extensively for filaments for
electric lamps, electron and television tubes, and for metal evaporation work; for
electrical contact points for automobile distributors; X-ray targets; windings and heating
elements for electrical furnaces; and for numerous spacecraft and high-temperature
applications. High-speed tool steels, Hastelloy(R), Stellite(R), and many other alloys
contain tungsten. Tungsten carbide is of great importance to the metal-working, mining,
and petroleum industries. Calcium and magnesium tungstates are widely used in
fluorescent lighting; other salts of tungsten are used in the chemical and tanning
industries. Tungsten disulfide is a dry, high-temperature lubricant, stable to 500C.
Tungsten bronzes and other tungsten compounds are used in paints. Tungsten powder
(99.9%) costs about $50/lb.
Source: CRC Handbook of Chemistry and Physics, 1913-1995. David R. Lide, Editor in Chief. Author: C.R.
Hammond
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