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Cobalt
Block dPeriod 4Group 9solid at 20 °C
Configuration :[Ar] 3d⁷ 4s²
Atomic mass :58.933194 u
3D Bohr-model representation of the Cobalt atom (symbol Co, atomic number Z=27). Electron shell configuration: 2, 8, 15, 2 electrons.
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Bohr model · educational
Electron configuration
Full1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷ 4s²
Short[Ar] 3d⁷ 4s²
Valence electrons9
KLMNOPQ shells
K2
L8
M15
N2
Electronegativity
Pauling1.88
Allen1.84
Mulliken (eV)—
Atomic radii
Empirical135 pm
Calculated152 pm
Covalent126 pm
Van der Waals—
Ionic radii (Shannon-Prewitt)
+274.5 pm
+361 pm
Successive ionisation energies
I₁760.4 kJ/mol
I₂1648 kJ/mol
I₃3232 kJ/mol
I₄4950 kJ/mol
I₅7670 kJ/mol
Electron affinity63.7 kJ/mol
Oxidation states
-3-10+1+2+3+4+5
Bold states = most common.