Template:Infobox cobalt

Cobalt,  ₂₇Co

electrolytically refined cobalt chips
General properties
Name, symbol	cobalt, Co
Appearance	hard lustrous gray metal
Pronunciation	/ˈkoʊbɒlt/ KOH-bolt
Cobalt in the periodic table
– ↑ Co ↓ Rh iron ← cobalt → nickel
Atomic number (Z)	27
Group, block	group 9, d-block
Period	period 4
Element category	transition metal
Standard atomic weight (±) (Ar)	58.933194(4)
Electron configuration	[Ar] 3d7 4s2
per shell	2, 8, 15, 2
Physical properties
Color	metallic gray
Phase	solid
Melting point	1768 K ​(1495 °C, ​2723 °F)
Boiling point	3200 K ​(2927 °C, ​5301 °F)
Density near r.t.	8.90 g/cm3
when liquid, at m.p.	8.86 g/cm3
Heat of fusion	16.06 kJ/mol
Heat of vaporization	377 kJ/mol
Molar heat capacity	24.81 J/(mol·K)
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1790 1960 2165 2423 2755 3198
Atomic properties
Oxidation states	−3, −1, +1, +2, +3, +4, +5 ​(an amphoteric oxide)
Electronegativity	Pauling scale: 1.88
Ionization energies	1st: 760.4 kJ/mol 2nd: 1648 kJ/mol 3rd: 3232 kJ/mol (more)
Atomic radius	empirical: 125 pm
Covalent radius	Low spin: 126±3 pm High spin: 150±7 pm
Miscellanea
Crystal structure	​hexagonal close-packed (hcp)
Speed of sound thin rod	4720 m/s (at 20 °C)
Thermal expansion	13.0 µm/(m·K) (at 25 °C)
Thermal conductivity	100 W/(m·K)
Electrical resistivity	62.4 nΩ·m (at 20 °C)
Magnetic ordering	ferromagnetic
Young's modulus	209 GPa
Shear modulus	75 GPa
Bulk modulus	180 GPa
Poisson ratio	0.31
Mohs hardness	5.0
Vickers hardness	1043 MPa
Brinell hardness	470–3000 MPa
CAS Number	7440-48-4
History
Discovery	Georg Brandt (1732)
Most stable isotopes of cobalt
iso NA half-life DM DE (MeV) DP 56Co syn 77.27 d ε 4.566 56Fe 57Co syn 271.79 d ε 0.836 57Fe 58Co syn 70.86 d ε 2.307 58Fe 59Co 100% 59Co is stable with 32 neutrons 60Co syn 5.2714 y β−, γ 2.824 60Ni

References

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