3D Bohr-model representation of the Selenium atom (symbol Se, atomic number Z=34). Electron shell configuration: 2, 8, 18, 6 electrons.
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Bohr model · educational
Bohr model of selenium
Selenium (Se) has 34 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) | 18 |
| N (n = 4) | 6 |
The Bohr model is a teaching picture: electrons do not travel in circular orbits, but the number of electrons per shell is exact.
Electron configuration
Full1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴
Short[Ar] 3d¹⁰ 4s² 4p⁴
Valence electrons6
KLMNOPQ shells
K2
L8
M18
N6
Electronegativity
Pauling2.55
Allen2.424
Mulliken (eV)—
Atomic radii
Empirical115 pm
Calculated103 pm
Covalent120 pm
Van der Waals190 pm
Ionic radii (Shannon-Prewitt)
-2198 pm
Successive ionisation energies
I₁941 kJ/mol
I₂2045 kJ/mol
I₃2973.7 kJ/mol
I₄4144 kJ/mol
I₅6590 kJ/mol
Electron affinity195 kJ/mol
Oxidation states
-2-1+1+2+3+4+5+6
Bold states = most common.
Warm-up
Selenium — do you remember?
3 questions on this page. The right answer shows every time, and nothing is asked of you to play.
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