What would be the electron configuration of Copper (Cu)?

Explanation:

In order to write the Copper electron configuration we first need to know the number of electrons for the Cu atom (there are 29 electrons). Once we have the configuration for Cu, the ions are simple. When we write the configuration we'll put all 29 electrons in orbitals around the nucleus of the Copper atom.

Therefore the expected electron configuration for Copper will be 1s22s22p63s23p64s23d9.

Half-filled and fully filled subshell have got extra stability. For the Cu+ ion we remove one electron from 4s1 leaving us with: 1s22s22p63s23p63d10.

For the Cu2+ ion we remove a total of two electrons (one from the 4s1 and one form the 3d10) leaving us with 1s22s22p63s23p63d9

Therefore, 1s22s22p63s23p63d9.

Hope this helps. Also note that copper is an exception to the rules for writing electron configurations.