Template:Infobox molybdenum

Molybdenum,  ₄₂Mo

General properties
Name, symbol	molybdenum, Mo
Appearance	gray metallic
Pronunciation	/ˌmɒlɪbˈdiːnəm/ or /məˈlɪbdᵻnəm/ MOL-ib-DEE-nəm or mə-LIB-di-nəm
Molybdenum in the periodic table
Cr ↑ Mo ↓ W niobium ← molybdenum → technetium
Atomic number (Z)	42
Group, block	group 6, d-block
Period	period 5
Element category	transition metal
Standard atomic weight (±) (Ar)	95.95(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)
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2742 2994 3312 3707 4212 4879
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
Miscellanea
Crystal structure	​body-centered cubic (bcc)
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)
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
History
Discovery	Carl Wilhelm Scheele (1778)
First isolation	Peter Jacob Hjelm (1781)
Most stable isotopes of molybdenum
iso NA half-life DM DE (MeV) DP 92Mo 14.84% >1.9×1020 y (β+β+) 1.6491 92Zr 93Mo syn 4×103 y ε – 93Nb 94Mo 9.25% – (SF) <4.485 95Mo 15.92% – (SF) <4.531 96Mo 16.68% – (SF) <5.771 97Mo 9.55% – (SF) <6.226 98Mo 24.13% >1×1014 y (β−β−) 0.1125 98Ru 99Mo syn 65.94 h β− 0.436, 1.214 99mTc γ 0.74, 0.36, 0.14 – 100Mo 9.63% 7.8×1018 y β−β− 3.04 100Ru
Decay modes in parentheses are predicted, but have not yet been observed

References

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