Copper (Cu)
Element 29 · transition metal · group 11, period 4
Copper is element 29, a transition metal in group 11 and period 4. Its electron configuration is [Ar] 3d10 4s1. The shells fill 2, 8, 18, 1. Courses differ here. Counting only the outer s subshell gives 1; counting the inner d subshell with it gives 11, which is the group number. It commonly forms ions with a charge of +2, +1.
- 29 protons
- 1/11 valence e−
- +2, +1
- d-block
Properties
| Atomic number | 29 |
|---|---|
| Symbol | Cu |
| Standard atomic weight | 63.546 u |
| Group | 11 |
| Period | 4 |
| Block | d-block |
| Category | transition metal |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s1 |
| Noble-gas notation | [Ar] 3d10 4s1 |
| Electrons per shell | 2, 8, 18, 1 |
| Valence electrons | 1 or 11 |
| Common ionic charge | +2, +1 |
| Electronegativity (Pauling) | 1.9 |
| Protons / electrons | 29 / 29 |
Electron configuration of copper
Orbitals fill from the lowest energy upward. Writing that out for copper gives 1s2 2s2 2p6 3s2 3p6 3d10 4s1, which is 1s2 2s2 2p6 3s2 3p6 3d10 4s1 in plain text.
Everything up to Ar is the same as in that noble gas, so it is usually abbreviated to [Ar] 3d10 4s1. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 6 | 6 |
| 3s | 2 | 2 |
| 3p | 6 | 6 |
| 3d | 10 | 10 |
| 4s | 1 | 2 |
Copper ion charge
Copper commonly forms ions with a charge of +2, +1.
Common questions
How many valence electrons does copper have?
There is no single agreed answer for copper. Courses differ here. Counting only the outer s subshell gives 1; counting the inner d subshell with it gives 11, which is the group number. Check which convention your course uses before answering.
What is the electron configuration of copper?
1s2 2s2 2p6 3s2 3p6 3d10 4s1, or [Ar] 3d10 4s1 written from the previous noble gas. Orbitals fill lowest energy first, but copper is one of the elements that breaks that order - a half-filled or filled d subshell is stable enough to be worth borrowing an s electron for.
What is the charge of copper?
Copper commonly forms ions with a charge of +2, +1. Transition metals have several accessible oxidation states, which is why more than one charge is listed.
How many protons, electrons and neutrons does copper have?
A neutral copper atom has 29 protons and 29 electrons. Its standard atomic weight is 63.546, so the most common isotope has about 35 neutrons.
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