Full configuration
1s² 2s² 2p⁶ 3s² 3p³
In the short form, [Ne] stands for the 10 electrons of neon, the noble gas before phosphorus. 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
Phosphorus is in group 15, period 3, in the p-block. It has 3 unpaired electrons in the ground state, so the atom is paramagnetic.
Configuration of phosphorus ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| P³⁻ | [Ar] | 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 |
|---|---|---|
| 12 | Magnesium | [Ne] 3s² |
| 13 | Aluminium | [Ne] 3s² 3p¹ |
| 14 | Silicon | [Ne] 3s² 3p² |
| 16 | Sulphur | [Ne] 3s² 3p⁴ |
| 17 | Chlorine | [Ne] 3s² 3p⁵ |
| 18 | Argon | [Ne] 3s² 3p⁶ |
Questions students ask
What is the electronic configuration of phosphorus?
[Ne] 3s² 3p³, or in full, 1s² 2s² 2p⁶ 3s² 3p³. Phosphorus has atomic number 15.
How many electrons are in each shell of phosphorus?
2, 8, 5 (K, L, M, N… shells in order).
How many unpaired electrons does phosphorus have?
3 in the ground state, so phosphorus atoms are paramagnetic.
What is the electronic configuration of P³⁻?
[Ar], with 0 unpaired electrons.