Write the electronic configurations of the following ions:
a) `H^(-)`, b) `Na^(+)` and c) `S^(2-)`

Explanation

a) `H^(-)=1s^(2)`,
b) `Na^(+)=1s^(2)2s^(2)2p^(6)` and
c) `S^(2-)=1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)`