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
Bohr model of cobalt
Cobalt (Co) has 27 electrons, spread over 4 shells. The diagram places them on circles around the nucleus, from the K shell — the closest — outward.
| Shell | Electrons |
|---|---|
| K (n = 1) | 2 |
| L (n = 2) | 8 |
| M (n = 3) | 15 |
| N (n = 4) | 2 |
The Bohr model is a teaching picture: electrons do not travel in circular orbits, but the number of electrons per shell is exact.
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Coordination chemistry — crystal field
Crystal field theory, d-orbital splitting, high/low spin complexes, complex color.
16 minElectron 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.
Warm-up
Cobalt — do you remember?
3 questions on this page. The right answer shows every time, and nothing is asked of you to play.
No account · one minute