Full configuration
1s² 2s² 2p⁶ 3s² 3p¹
In the short form, [Ne] stands for the 10 electrons of neon, the noble gas before aluminium. Only the electrons after it are written out.
Orbital diagram
2p↑↓↑↓↑↓
3s↑↓
3p↑
Outer subshells only. Each box is an orbital; electrons fill singly first (Hund's rule), then pair up with opposite spins.
What the configuration tells you
Aluminium is in group 13, period 3, in the p-block. It has 1 unpaired electron in the ground state, so the atom is paramagnetic.
Configuration of aluminium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Al³⁺ | [Ne] | 0 | 0.00 |
Moment is the spin-only magnetic moment μ = √(n(n + 2)) Bohr magnetons, where n is the number of unpaired electrons.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 10 | Neon | [He] 2s² 2p⁶ |
| 11 | Sodium | [Ne] 3s¹ |
| 12 | Magnesium | [Ne] 3s² |
| 14 | Silicon | [Ne] 3s² 3p² |
| 15 | Phosphorus | [Ne] 3s² 3p³ |
| 16 | Sulphur | [Ne] 3s² 3p⁴ |
Questions students ask
What is the electronic configuration of aluminium?
[Ne] 3s² 3p¹, or in full, 1s² 2s² 2p⁶ 3s² 3p¹. Aluminium has atomic number 13.
How many electrons are in each shell of aluminium?
2, 8, 3 (K, L, M, N… shells in order).
How many unpaired electrons does aluminium have?
1 in the ground state, so aluminium atoms are paramagnetic.
What is the electronic configuration of Al³⁺?
[Ne], with 0 unpaired electrons.