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Tungsten

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Tungsten

Tungsten (also called wolfram) is a chemical element; it has symbol W (from German: Wolfram). Its atomic number is 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternative name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements, melting at 3,422 °C (6,192 °F; 3,695 K). It also has the highest boiling point, at 5,930 °C (10,706 °F; 6,203 K). Its density is 19.254 g/cm3, comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work into metal. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in gas tungsten arc welding, superalloys, and radiation shielding. Tungsten's hardness and high density make it suitable for military applications in penetrating projectiles. Tungsten compounds are often used as industrial catalysts. Its largest use is in tungsten carbide, a wear-resistant material used in metalworking, mining, and construction. About 50% of tungsten is used in tungsten carbide, with the remaining major use being alloys and steels: less than 10% is used in other compounds. Tungsten is the only metal in the third transition series that is known to occur in biomolecules, found in a few species of bacteria and archaea. However, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to most forms of animal life.

Infobox

Pronunciation
/ˈtʌŋstən/ ⓘ (TUNG-stən)
Alternative name
Wolfram, pronounced: /ˈwʊlfrəm/ (WUUL-frəm)
Allotropes
α-tungsten (common), β-tungsten
Appearance
Grayish white, lustrous
Atomic number (Z)
74
Group
group 6
Period
period 6
Block
d-block
Electron configuration
[Xe] 4f14 5d4 6s2
Electrons per shell
2, 8, 18, 32, 12, 2
Phase at STP
solid
Melting point
3695 K (3422 °C, 6192 °F)
Boiling point
6203 K (5930 °C, 10706 °F)
Density (at 20° C)
19.254 g/cm3
when liquid (at m.p.)
17.6 g/cm3
Heat of fusion
52.31 kJ/mol
Heat of vaporization
774 kJ/mol
Molar heat capacity
24.27 J/(mol·K)
P (Pa)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 3477 3773 4137 4579 5127 5823
at T (K)
3477
Oxidation states
common: 4, 6 −4, −2, −1, 0, 1, 2, 3, 5
Electronegativity
Pauling scale: 2.36
Ionization energies
1st: 770 kJ/mol 2nd: 1700 kJ/mol
Atomic radius
empirical: 139 pm
Covalent radius
162±7 pm
Natural occurrence
primordial
Crystal structure
body-centered cubic (bcc) (cI2)
Lattice constant
a = 316.52 pm (at 20 °C)
Thermal expansion
4.42×10−6/K (at 20 °C)
Thermal conductivity
173 W/(m⋅K)
Electrical resistivity
52.8 nΩ⋅m (at 20 °C)
Magnetic ordering
paramagnetic
Molar magnetic susceptibility
59.0×10−6 cm3/mol (298 K)
Young's modulus
411 GPa
Shear modulus
161 GPa
Bulk modulus
310 GPa
Speed of sound thin rod
4620 m/s (at r.t.) (annealed)
Poisson ratio
0.28
Mohs hardness
7.5
Vickers hardness
3430–4600 MPa
Brinell hardness
2000–4000 MPa
CAS Number
7440-33-7
Naming
the old Swedish name for the mineral scheelite, from which it was isolated; means 'heavy stone'
Discovery and first isolation
Juan José Elhuyar and Fausto Elhuyar (1783)
Named by
Torbern Bergman (1781)
Symbol
"W": from Wolfram, originally from Middle High German wolf-rahm 'wolf's foam' describing the mineral wolframite
Main isotopes
mw- body Main isotopes Decay Isotope abun­dance half-life (t1/2) mode pro­duct 180W 0.120% 1.59×1018 y α 176Hf 181W synth 120.96 d ε 181Ta 182W 26.5% stable 183W 14.3% stable 184W 30.6% stable 185W synth 75.1 d β− 185Re 186W 28.4% stable 187W synth 23.81 h β− 187Re 188W synth 69.77 d β− 188Re
180W
0.120%
181W
synth
182W
26.5%
183W
14.3%
184W
30.6%
185W
synth
186W
28.4%
187W
synth
188W
synth

Tables

at T (K)
at T (K)
P (Pa)
at T (K)
1
3477
10
3773
100
4137
1 k
4579
10 k
5127
100 k
5823
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
3477
3773
4137
4579
5127
5823
mw- Isotope
mw- Isotope
Main isotopes
mw- Isotope
Main isotopes
abun­dance
Main isotopes
half-life (t1/2)
Decay
mode
Decay
pro­duct
180W
180W
Main isotopes
180W
Main isotopes
0.120%
Main isotopes
1.59×1018 y
Decay
α
Decay
176Hf
181W
181W
Main isotopes
181W
Main isotopes
synth
Main isotopes
120.96 d
Decay
ε
Decay
181Ta
182W
182W
Main isotopes
182W
Main isotopes
26.5%
Main isotopes
stable
183W
183W
Main isotopes
183W
Main isotopes
14.3%
Main isotopes
stable
184W
184W
Main isotopes
184W
Main isotopes
30.6%
Main isotopes
stable
185W
185W
Main isotopes
185W
Main isotopes
synth
Main isotopes
75.1 d
Decay
β−
Decay
185Re
186W
186W
Main isotopes
186W
Main isotopes
28.4%
Main isotopes
stable
187W
187W
Main isotopes
187W
Main isotopes
synth
Main isotopes
23.81 h
Decay
β−
Decay
187Re
188W
188W
Main isotopes
188W
Main isotopes
synth
Main isotopes
69.77 d
Decay
β−
Decay
188Re
Main isotopes
Decay
mw- Isotope
abun­dance
half-life (t1/2)
mode
pro­duct
180W
0.120%
1.59×1018 y
α
176Hf
181W
synth
120.96 d
ε
181Ta
182W
26.5%
stable
183W
14.3%
stable
184W
30.6%
stable
185W
synth
75.1 d
β−
185Re
186W
28.4%
stable
187W
synth
23.81 h
β−
187Re
188W
synth
69.77 d
β−
188Re

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