Wolfram is also known as tungsten, which is
Swedish for heavy stone. The atomic symbol for Wolfram is W. The atomic number is 74. The
atomic weight is 183.5 grams. Its oxidation states are +2, +3, +4, +5, and +6 with six the
most stable. The density of wolfram is 19300 kg/m^3 (19.3 g/ml). Its boiling temperature
is 6203 Kelvins (5930 degrees Celsius). Its melting point is 3683 Kelvins (3410 degrees
Celsius). Natural tungsten has 5 stable isotopes. 21 unstable isotopes are recognized.
Tungsten occurs in wolframite, scheelite, huegnerite, and ferberite. Deposits of tungsten
occur in California, Colorado, South Korea, Russia, Portugal, China and Bolivia. China is
reported to have 75% of the world’s tungsten resources.
In 1779 Peter Woulfe examined the mineral now known as wolfamite and concluded that it
contained a new substance. In 1781, Scheele found that a new acid could be found in
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
Elhuyar brothers are credited with the discovery of tungsten because they found that an
acid in wolframite in 1783 that was identical to the acid of tungsten of Scheele, and
obtained that element by reduction of this acid with charcoal also in 1783.
Tungsten has its own industry. It is used for filaments for electric lamps, X-ray
targets, electron and television tubes, metal and evaporation work, electrical contact
points for automobile distributors, windings and heating elements for electrical furnaces,
and for numerous spacecraft and for machines that work in high temperatures. Tungsten
carbide is useful in the metalworking, petroleum, and mining industries. Magnesium and
calcium tungstenates are widely used in fluorescent lighting. Tungsten bronzes and other
tungsten compounds are used in paints. Some salts of tungsten are used in the chemical and
tanning industries. Tungsten can be forged, spun, drawn, and extruded, but impure tungsten
is brittle and hard to work with. The metal oxidizes in air and has to be protected at
high temperatures. It has great corrosion resistance and is attacked only slightly by most
mineral acids.
A mole indicates the quantity of a substance that is equal to its molecular mass in
grams. It is also equal to Avagadro’s number which is 6.02 times 10^23 molecules.
Moles are important because they can be used to find the number of molecules in a
substance from the mass of the substance and vice versa. This is important especially in
labs.
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