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Atomic: M.A.C. | Reference
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Cobalt
Electrons per shell 2,8,15,2
Electron Configuration [Ar] 3d7 4s2 open electron config
Ground state 4F9/2
Atomic Volume 6.7 cm3 mol-1
Electronegativity 1.88
Magnetic ordering Ferromagnetic
Speed of sound 4720 m s-1
Thermal Properties
Enthalpy of Atomization 26.8 kJ mol-1 @25°C
Enthalpy of Fusion 15.2 kJ mol-1
Enthalpy of Vaporisation 382.4 kJ mol-1
Heat Capacity 24.81 J mol-1 K-1
Thermal Conductivity 100 W m-1 K-1
Thermal Expansion 13 μm m-1 K-1
Hardness
Brinell hardness 700 MPa
Mohs hardness 5.0
Vickers hardness 1043 MPa
Elastic Properties
Bulk modulus 180 GPa
Poisson ratio 0.31
Shear modulus 75 GPa
Young's modulus 209 GPa
Electrical Properties
Electrical resistivity 6 Ω m
Electrical conductivity 0.172 106/cm Ω
Chemical Properties
Electrochemical Equivalent 1.0994 g Ah-1
Electron Work Function 5 eV
Valence Electron Potential (-eV) 38.7
Ionization Potential  
First 7.86
Second 17.06
Third 33.5
Incompatibilities Strong oxidizers, ammonium nitrate (NH4NO3).
Flammability
Non-combustible solid (except as dust)
Energy Levels
Kα1 (intensity 100) 6.93032 KeV
Kα2 (intensity 50) 6.9153 KeV
Kβ1 (intensity 20) 7.64943 KeV
Lα1 (intensity 100) 0.7762 KeV
Lα2 (intensity 10) 0.7762 KeV
Lβ1 (intensity 24.1) 0.7914 KeV
Lβ3 (intensity 3) 0.866 KeV
Lβ4 (intensity 0.5) 0.866 KeV
Lγ3 (intensity 13) 0.694 KeV
Ll (intensity 40) 0.6773 KeV
Atomic Radii
Empirical 135 pm
Bohr Radius 152 pm
Covalent Radius 126 pm
Van der Waals No data.
Triple covalent 96 pm
Metallic 125 pm
Oxidation States
Main Co+2
Other Co-1, Co0, Co+1, Co+3, Co+4, Co+5
Ionisation Energies (kJ mol-1) show graph
M - M+ 760
M+ - M2+ 1646
M2+ - M3+ 3232
M3+ - M4+ 4950
M4+ - M5+ 7670
M5+ - M6+ 9840
M6+ - M7+ 12400
M7+ - M8+ 15100
M8+ - M9+ 17900
M9+ - M10+ 26600
Vapour Pressure
P (Pa) 1 10 100 1K 10K 100K
T (K) 1790 1960 2165 2423 2755 3198
Crystal Structure
Structure Hexagonal close packed
a = 250.71 pm
b = 250.71 pm
c = 406.95 pm
α = 90°
β = 90°
γ = 120°