Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹
In the short form, [Ar] stands for the 18 electrons of argon, the noble gas before gallium. Only the electrons after it are written out.
Orbital diagram
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
Gallium is in group 13, period 4, in the p-block. It has 1 unpaired electron in the ground state, so the atom is paramagnetic.
Configuration of gallium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Ga³⁺ | [Ar] 3d¹⁰ | 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 |
|---|---|---|
| 28 | Nickel | [Ar] 3d⁸ 4s² |
| 29 | Copper | [Ar] 3d¹⁰ 4s¹ |
| 30 | Zinc | [Ar] 3d¹⁰ 4s² |
| 32 | Germanium | [Ar] 3d¹⁰ 4s² 4p² |
| 33 | Arsenic | [Ar] 3d¹⁰ 4s² 4p³ |
| 34 | Selenium | [Ar] 3d¹⁰ 4s² 4p⁴ |
Questions students ask
What is the electronic configuration of gallium?
[Ar] 3d¹⁰ 4s² 4p¹, or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹. Gallium has atomic number 31.
How many electrons are in each shell of gallium?
2, 8, 18, 3 (K, L, M, N… shells in order).
How many unpaired electrons does gallium have?
1 in the ground state, so gallium atoms are paramagnetic.
What is the electronic configuration of Ga³⁺?
[Ar] 3d¹⁰, with 0 unpaired electrons.