What is the electron configuration of Cl-?
and in ground state (no charge), the number of protons is equal to the number of electrons, then
Therefore, the ground state electron configuration of the element, chlorine is:
For a ground state element to become an ion, it has to either gain or lose an electron in its outermost orbital. Elements usually do this in order to gain the electron stability of the noble gases (octet rule).
Now, for you to be not confuse, you always have to remember that:
(1) electron gain will result to a
(2) electron loss will result to a
The chloride ion,
Thus, the electron configuration for