Electron Configuration of Copper (Cu)
Copper (Cu, Z = 29) has the electron configuration [Ar] 3d¹⁰ 4s¹, filling 4 shells with 2, 8, 18, 1 electrons.
Teachers call it "one fact, fully handled" — exactly what this page does for Copper. The answer sits at the top in bold; scroll for the working, the shell-by-shell breakdown and the two questions students ask most. Need the whole picture instead — history, characteristics, uses, exam questions? The full Copper page is one click away.
Copper: every subshell, one by one
Start from 1s and follow the running total: this is exactly how examiners expect you to build Copper's configuration on paper.
| Subshell | Electrons | Total so far |
|---|---|---|
| [Ar] | 0 | 18 |
| 3d | 10 | 28 |
| 4s | 1 | 29 |
Electrons per shell (K, L, M…)
Grouped by principal quantum number instead of subshell, Copper carries 2 in shell 1, 8 in shell 2, 18 in shell 3, 1 in shell 4. The outermost shell holds 1 electron — the ones that do all the bonding.
How to derive it yourself
Follow the aufbau order (1s → 2s → 2p → 3s → 3p → 4s → 3d → …), pouring 29 electrons into orbitals of capacity 2 (s), 6 (p), 10 (d) and 14 (f) until none remain. Write the filled inner shells as the nearest noble-gas core — for Copper that gives [Ar] 3d¹⁰ 4s¹.
Note: Copper is one of the textbook exceptions to strict aufbau filling — a half-filled or fully-filled d subshell buys extra stability, so its ground-state configuration is [Ar] 3d¹⁰ 4s¹.
Students also ask
How many electron shells does Copper have?
Copper is in period 4, so its electrons occupy 4 shells, holding 2, 8, 18, 1 electrons respectively.
How many valence electrons does Copper have?
Its outermost shell holds 1 electron, so Copper has 1 valence electron that take part in bonding.
What is the noble-gas shorthand for Copper?
The shorthand form is exactly [Ar] 3d¹⁰ 4s¹.