Pages

Sunday, June 19, 2016

Molybdenum chemical element

Molybdenum was discovered by Carl Wilhelm Scheele in 1778.
The chemical symbol for Molybdenum is Mo and its atomic number is 42.
We find it listed in the periodic table in Group 6 and period 5 and block.
Molybdenum belongs to the family of transition metals such as for example the Silver, the Bohrium, cadmium, ...
This element is stable.
Molybdenum came from the word molubdaina.


Molybdenum chemical element


Atomic number (Z) 42
Group, block group 6, d-block
Period: period 5
Element category: transition metal
Standard atomic weight (±) (Ar) 95.95(1)[1]
Electron configuration: [Kr] 4d5 5s1
per shell: 2, 8, 18, 13, 1

Physical properties
Phase: solid
Melting point: 2896 K ​(2623 °C, ​4753 °F)
Boiling point: 4912 K ​(4639 °C, ​8382 °F)
Density near r.t. : 10.28 g/cm3
when liquid, at m.p. 9.33 g/cm3
Heat of fusion: 37.48 kJ/mol
Heat of vaporization: 598 kJ/mol
Molar heat capacity: 24.06 J/(mol·K)

Atomic properties
Oxidation states: 6, 5, 4, 3, 2, 1,−1, −2, −4 ​(a strongly acidic oxide)
Electronegativity: Pauling scale: 2.16
Ionization energies 1st: 684.3 kJ/mol
2nd: 1560 kJ/mol
3rd: 2618 kJ/mol
Atomic radius empirical: 139 pm
Covalent radius: 154±5 pm

Crystal structure: body-centered cubic 
Speed of sound thin rod: 5400 m/s (at r.t.)
Thermal expansion: 4.8 µm/(m·K) (at 25 °C)
Thermal conductivity: 138 W/(m·K)
Thermal diffusivity: 54.3 mm2/s (at 300 K)[3]
Electrical resistivity: 53.4 nΩ·m (at 20 °C)
Magnetic ordering: paramagnetic
Young's modulus: 329 GPa
Shear modulus: 126 GPa
Bulk modulus: 230 GPa
Poisson ratio: 0.31
Mohs hardness: 5.5
Vickers hardness: 1400–2740 MPa
Brinell hardness: 1370–2500 MPa
CAS Number: 7439-98-7