Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s²
In the short form, [Kr] stands for the 36 electrons of krypton, the noble gas before cadmium. 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
Cadmium is in group 12, period 5, in the d-block. It has 0 unpaired electrons in the ground state, so the atom is diamagnetic.
Configuration of cadmium ions
| Ion | Configuration | Unpaired | Moment (BM) |
|---|---|---|---|
| Cd²⁺ | [Kr] 4d¹⁰ | 0 | 0.00 |
Moment is the spin-only magnetic moment μ = √(n(n + 2)) Bohr magnetons, where n is the number of unpaired electrons. Positive ions lose electrons from the outermost shell first, so transition metals lose their 4s or 5s electrons before d.
Nearby elements
| Z | Element | Configuration |
|---|---|---|
| 45 | Rhodium | [Kr] 4d⁸ 5s¹ |
| 46 | Palladium | [Kr] 4d¹⁰ |
| 47 | Silver | [Kr] 4d¹⁰ 5s¹ |
| 49 | Indium | [Kr] 4d¹⁰ 5s² 5p¹ |
| 50 | Tin | [Kr] 4d¹⁰ 5s² 5p² |
| 51 | Antimony | [Kr] 4d¹⁰ 5s² 5p³ |
Questions students ask
What is the electronic configuration of cadmium?
[Kr] 4d¹⁰ 5s², or in full, 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s². Cadmium has atomic number 48.
How many electrons are in each shell of cadmium?
2, 8, 18, 18, 2 (K, L, M, N… shells in order).
How many unpaired electrons does cadmium have?
0 in the ground state, so cadmium atoms are diamagnetic.
What is the electronic configuration of Cd²⁺?
[Kr] 4d¹⁰, with 0 unpaired electrons.