Question

In what order do electrons get removed for the formation of an ion?

For example, for the formation of `Cu^(3+)` ion, after the removal of first electron from 4s, in which order would the next two electrons get removed i.e. are both electrons removed from same orbital or are both electrons removed from two different orbitals ?

P.S. I understand that `Cu^(3+)` is not stable but please still answer my question.

Answer 1

Ok, so when you figure out the positions of electrons in different suborbitals, you go by energy level (so the order is 1s 2s 2p 3s 3p 4s 3d etc.).

However, when you're removing electrons to form ions, you go by orbitals (so the reversed order is 1s 2s 2p 3s 3p 3d 4s etc.).

So copper has electron configuration `["Ar"]\ 3d^10\ 4s^1`. The first electron removed is from `4s`, which leaves `["Ar"]\ 3d^10`. The second and third electrons are from the `3d` suborbital, leaving `["Ar"]\ 3d^8`.