Copper Electron Configuration
★ Exception to the Aufbau order. Predicted 1s2 2s2 2p6 3s2 3p6 3d9 4s2; measured 1s2 2s2 2p6 3s2 3p6 3d10 4s1.
Orbital diagram
- Valence electrons
- 11
- Unpaired electrons
- 1
- Block
- d-block
- Magnetism (atom)
- paramagnetic
Electrons per shell
| K (n = 1) | 2 |
|---|---|
| L (n = 2) | 8 |
| M (n = 3) | 18 |
| N (n = 4) | 1 |
Copper ion configurations
| Ion | Electrons | Configuration |
|---|---|---|
| Cu+ | 28 | [Ar] 3d10 |
| Cu2+ | 27 | [Ar] 3d9 |
How to write it
Place 29 electrons into subshells in the Aufbau order (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p), filling s with 2, p with 6, d with 10 and f with 14. Copper sits in period 4, group 11, in the d-block, so its last electron enters a d subshell. Replacing the inner electrons with the previous noble gas gives the shorthand [Ar] 3d10 4s1.
Try copper and its ions in the calculator, or see the full copper data sheet.
Copper electron configuration FAQ
What is the electron configuration of copper?
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹. Shorthand (noble gas) notation: [Ar] 3d¹⁰ 4s¹.
What is the noble gas configuration of copper?
[Ar] 3d¹⁰ 4s¹. The bracket stands for the Ar core electrons.
Why is copper’s electron configuration an exception?
The simple filling (Aufbau) order predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹ 4s², but the measured ground state is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹. Shifting an electron gives a half-filled or filled subshell, which has extra exchange stability.
How many valence electrons does copper have?
11 (1 outer s + 10 d electrons; 1 in the outermost shell).
How many unpaired electrons does copper have?
1 in the ground state, following Hund’s rule. An atom with unpaired electrons is paramagnetic.
What is the electron configuration of Cu+?
[Ar] 3d¹⁰ (28 electrons). Transition metal cations lose their outer s electrons before d electrons.
What is the electron configuration of Cu2+?
[Ar] 3d⁹ (27 electrons). Transition metal cations lose their outer s electrons before d electrons.