Tungsten

Tungsten (also called wolfram)[9][10] is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name.

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Tungsten, ₇₄W

Tungsten
Pronunciation	/ˈtʌŋstən/ ​(TUNG-stən)
Alternative name	wolfram, pronounced: /ˈwʊlfrəm/ (WUUL-frəm)
Allotropes	α-tungsten (common), β-tungsten
Appearance	grayish white, lustrous
Standard atomic weight Ar°(W)
	183.84±0.01 183.84±0.01 (abridged)[1]
Tungsten in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Mo ↑ W ↓ Sg tantalum ← tungsten → rhenium
Atomic number (Z)	74
Group	group 6
Period	period 6
Block	d-block
Electron configuration	[Xe] 4f14 5d4 6s2[2]
Electrons per shell	2, 8, 18, 32, 12, 2
Physical properties
Phase at STP	solid
Melting point	3695 K ​(3422 °C, ​6192 °F)
Boiling point	6203 K ​(5930 °C, ​10706 °F)
Density (near r.t.)	19.25 g/cm3
when liquid (at m.p.)	17.6 g/cm3
Heat of fusion	52.31 kJ/mol[3][4]
Heat of vaporization	774 kJ/mol
Molar heat capacity	24.27 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 3477 3773 4137 4579 5127 5823
Atomic properties
Oxidation states	−4, −2, −1, 0, +1, +2, +3, +4, +5, +6 (a mildly acidic oxide)
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
Spectral lines of tungsten
Other properties
Natural occurrence	primordial
Crystal structure	​body-centered cubic (bcc)
Speed of sound thin rod	4620 m/s (at r.t.) (annealed)
Thermal expansion	4.5 µm/(m⋅K) (at 25 °C)
Thermal conductivity	173 W/(m⋅K)
Electrical resistivity	52.8 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic[5]
Molar magnetic susceptibility	+59.0×10−6 cm3/mol (298 K)[6]
Young's modulus	411 GPa
Shear modulus	161 GPa
Bulk modulus	310 GPa
Poisson ratio	0.28
Mohs hardness	7.5
Vickers hardness	3430–4600 MPa
Brinell hardness	2000–4000 MPa
CAS Number	7440-33-7
History
Discovery and first isolation	Juan José Elhuyar and Fausto Elhuyar[7] (1783)
Named by	Torbern Bergman (1781)
Symbol	"W": from Wolfram, originally from Middle High German wolf-rahm 'wolf's foam' describing the mineral wolframite[8]
Isotopes of tungsten v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 180W 0.120% 1.8×1018 y α 176Hf 181W synth 121.2 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
Category: Tungsten view talk edit | references

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).[11] Its density is 19.30 grams per cubic centimetre (0.697 lb/cu in),[12] comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead.[13] Polycrystalline tungsten is an intrinsically brittle[14][15][16] 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.[17]

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.

Tungsten is the only metal in the third transition series that is known to occur in biomolecules, being 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.[18][19]