18Ar39.95
Argon
Noble gasesBlock pPeriod 3Group 18gas at 20 °C
- Configuration :
- [Ne] 3s² 3p⁶
- Atomic mass :
- 39.95 u
3D Bohr-model representation of the Argon atom (symbol Ar, atomic number Z=18). Electron shell configuration: 2, 8, 8 electrons.
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Bohr model · educational
Bohr model of argon
Argon (Ar) has 18 electrons, spread over 3 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) | 8 |
The Bohr model is a teaching picture: electrons do not travel in circular orbits, but the number of electrons per shell is exact.
Related lesson
Electron configuration
Filling rules (Aufbau, Pauli, Hund), notations like [Ar] 4s² 3d⁶, valence electrons. Iron, copper, transition metal cases.
12 minElectron configuration
Full1s² 2s² 2p⁶ 3s² 3p⁶
Short[Ne] 3s² 3p⁶
Valence electrons8
KLMNOPQ shells
K2
L8
M8
Electronegativity
Pauling—
Allen3.242
Mulliken (eV)—
Atomic radii
Empirical71 pm
Calculated71 pm
Covalent106 pm
Van der Waals188 pm
Successive ionisation energies
I₁1520.6 kJ/mol
I₂2665.8 kJ/mol
I₃3931 kJ/mol
I₄5771 kJ/mol
I₅7238 kJ/mol
Electron affinity—
Oxidation states
0
Bold states = most common.
Warm-up
Argon — 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