Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s²
In the short form, [Kr] stands for the 36 electrons of krypton, the noble gas before strontium. 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
Strontium is in group 2, period 5, in the s-block. It has 0 unpaired electrons in the ground state, so the atom is diamagnetic.
Configuration of strontium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Sr²⁺ | [Kr] | 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 |
|---|---|---|
| 35 | Bromine | [Ar] 3d¹⁰ 4s² 4p⁵ |
| 36 | Krypton | [Ar] 3d¹⁰ 4s² 4p⁶ |
| 37 | Rubidium | [Kr] 5s¹ |
| 39 | Yttrium | [Kr] 4d¹ 5s² |
| 40 | Zirconium | [Kr] 4d² 5s² |
| 41 | Niobium | [Kr] 4d⁴ 5s¹ |
Questions students ask
What is the electronic configuration of strontium?
[Kr] 5s², or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 5s². Strontium has atomic number 38.
How many electrons are in each shell of strontium?
2, 8, 18, 8, 2 (K, L, M, N… shells in order).
How many unpaired electrons does strontium have?
0 in the ground state, so strontium atoms are diamagnetic.
What is the electronic configuration of Sr²⁺?
[Kr], with 0 unpaired electrons.