Question

The common charges of an element can be related to the electron configuration of the element. Why would copper ions have two common charges? Explain each of them in terms of the electron configuration.

Answer 1

The electron configuration for copper, atomic number 29 (29 electrons) is:

<-----this would be the expected electron configuration but copper has an exception:

<----notice how 1 electron of the 4s subshell jumped into the 3d subshell to complete the 10 electron.

In order to form a ion the atom looses an electron from the highest subshell, in this case from the 4s, and yields:

At first look this would look energeticaly favorable yielding a Cu+ ion stable, but it is not true, since the Jahn Teller effect explains that the a d orbital is more stable with certain number of electrons in its sorroundings, hence the copper is more stable loosing another electron: