Physical properties of tungsten

       Physical properties of tungsten

Tungsten is obtained industrially by the decomposition of tungsten oxide by the reaction of hydrogen or carbon. Pure tungsten is a metal between off-white and tin-white. Pure tungsten can be cut with a hacksaw, as well as forged, spun, drawn and extruded. Impure tungsten is fragile and difficult to do so. Tungsten has the highest melting point among all metals, and has the highest tensile strength when the temperature exceeds 1650°C. Metals are oxidized in air and must be stored at high temperatures. Tungsten is very resistant to corrosion, and most mineral acids can only slightly corrode it.



The physical properties of tungsten are as follows:



Element symbol: W

         Atomic Number: 74

         Nuclear charge number: 74

CAS: 7440-33-7[1]

         Stable isotopes and their percentages: 180(0.14); 182(26.41); 183(14.40); 184(30.64); 186(28.41)

Atomic volume: (cc/mol) 9.53

         Relative atomic mass: 183.84

         The content of elements in the sun: (ppm) 0.004%

         The content of elements in seawater: (ppm) 0.000092%

         Electronic shell structure of free atoms: 1s22s22p63s23p63d104s24p64d104f145s25P65d46S2

         Atomic radius: 137pm

         Peripheral electron layer arrangement: 5d4 6s2

         Electron layer: K-L-M-N-O-P

         The speed of sound in it: (m/S) 4620

         Oxidation state: Main W-4, W-2, W-1, W0, W+2, W+3, W+4, W+5, W+6

         Ionization energy (kJ/mol): M - M+ 770 M+ - M2+ 1700 M2+ - M3+ 2300 M3+ - M4+ 3400 M4+ - M5+ 4600 M5+ - M6+ 5900

         First ionization energy: 775kJ/mol.

         Electronegativity: 1.7.

         Density: 19.35 grams per cubic centimeter.

         Crystal structure and lattice constants:

α-W: The unit cell is a body-centered cubic unit cell, and each unit cell contains 2 metal atoms. β-W: cubic lattice a=5.046 nm (below 630°C

Cell parameters:   

a = 316.52 pm

b = 316.52 pm

c = 316.52 pm

α = 90°

β = 90°

γ = 90°

         Melting point: 3410±20℃

         Boiling point: 5927℃

         Mohs hardness: 7.5

         Latent heat of fusion: 40.13±6.67kJ/mol

         Sublimation heat: 847.8 kJ/mol (25℃)

         Heat of evaporation: 823.85±20.9kJ/mol (boiling point)

         Resistance temperature coefficient: 0.00482 I/℃

Electron work function: 4.55 eV

         Thermal neutron capture surface: 19.2 b

         Elastic modulus: 35000—38000 MPa (wire)

         Torsional modulus: ~36000Mpa

         Bulk modulus: 3.108×1011－1.579×107t+0.344×103t2 Pa

         Shear modulus: 4.103×1011－3.489×107t+7.55×103t2 Pa

         Compressibility: 2.910-7 cm/kg

         Tungsten is available in two variants, alpha and beta. At standard temperature and pressure, the α-type is a stable body-centered cubic structure. Beta tungsten can only appear in the presence of oxygen. It is stable below 630 °C, and is converted into α tungsten above 630 °C, and this process is irreversible.