H' at. wt. (natural) 1.007967
at. wt. (H') 1.007822
at. no. 1
m.p. - 259.140C
b.p. - 252.870C
density 0.08988 gm./l
density (liquid) 70.8 gm/i. (-2530C)
density (solid) 7016 gm/i. (-2620C)
valence 1.
Electronic configuration
| K |
L |
M |
N |
O |
P |
Q |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
| s |
s p |
s p d |
s p d f |
s p d f |
s p d f |
s p d f |
| 1 |
|
|
|
|
|
|
TUNGSTEN (Swedish, tung sten, heavy stone); also
known as WOLFRAM (from woframite, said to be named
from woff rahm or spumi lupi, because the ore interfered with
the smelting of tin and was supposed to devour the tin),
W; at. wt. 183.85; at. no.74; m.p. 34l0t200C; b.p. 59270C;
sp. gr. 19.3 (200C); valence 2, 3, 4, 5, or 6. In 1779 Peter
Woulfe examined the mineral now known as wotj?amite 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 Bergman suggested the possibility of obtaining
a new metal by reducing this acid. The de Elhuyar brothers
found an acid in wo~amite in 1783 that was identical to the
acid of lung sten (tungstic acid) of Scheele, and in that year
they succeeded in obtaining the element by reduction of this
acid with charcoal. Tungsten occurs in wo~amite, (Fe,
Mn)W04; scheelite, CaWO4; huetnerite, MnWO4; and
ferberite, FeWO4. Important deposits of tungsten occur in
California, North Carolina, South Korea, Bolivia, U.S.S.R.,
and Portugul. China is reported to have about 75 % of the
world's tungsten resources. Natural tungsten contains five
stable isotopes. Twelve other unstable isotopes are recog-
nized. The metal is obtained commercially by reducing
tungstic oxide with hydrogen or cargon. Pure tungsten is a
steel 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 melfing point
and lowest vapor pressure of all metals, and at temperatures
over 16500C has the highest tensile strength. The metal
oxidizes in air and must be protected at elevated tempera-
tures. It has excellent corrosion resistance and is attacked
only slightly by most mineral acids. The thermal expansion
is about the same as boro-silicate glass, which makes the
metal useful for glass-td-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 fur-
naces; and for numerous space missile and high-temperature
applications. High-speed tool steels, Hastelloys, Stellite,
and many other alloys contain tungsten. Tungsten carbide
is of great importance to the metalworking, mining, and
petroleum industries. Calcium and magnesium tungstates
are widely used in fluorescent lighting; other salts of tung-
sten are used in the chemical, and tanning industries.
Tungsten disulfide is a dry, high-temperature lubricant,
stable to 5000C. Tungsten bronzes and other tungsten
compounds are used in paints. Hydrogen-reduced tungsten
powder costs about 55/lb.
© 1999 F. Davies
Delphi O.E.M. Co.
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