Full configuration
1s² 2s² 2p⁶ 3s²
In the short form, [Ne] stands for the 10 electrons of neon, the noble gas before magnesium. Only the electrons after it are written out.
Orbital diagram
2s↑↓
2p↑↓↑↓↑↓
3s↑↓
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
Magnesium is in group 2, period 3, in the s-block. It has 0 unpaired electrons in the ground state, so the atom is diamagnetic.
Configuration of magnesium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Mg²⁺ | [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 |
|---|---|---|
| 9 | Fluorine | [He] 2s² 2p⁵ |
| 10 | Neon | [He] 2s² 2p⁶ |
| 11 | Sodium | [Ne] 3s¹ |
| 13 | Aluminium | [Ne] 3s² 3p¹ |
| 14 | Silicon | [Ne] 3s² 3p² |
| 15 | Phosphorus | [Ne] 3s² 3p³ |
Questions students ask
What is the electronic configuration of magnesium?
[Ne] 3s², or in full, 1s² 2s² 2p⁶ 3s². Magnesium has atomic number 12.
How many electrons are in each shell of magnesium?
2, 8, 2 (K, L, M, N… shells in order).
How many unpaired electrons does magnesium have?
0 in the ground state, so magnesium atoms are diamagnetic.
What is the electronic configuration of Mg²⁺?
[Ne], with 0 unpaired electrons.