Question

Which has the lowest ionization energy: `S, S^(2-), S^(2+)`?

Answer 1

`S^(2+)`

Explanation:

S and `S^(2+)` are both 2 electrons away from having a complete valence shell (8 and 2 electrons), but it would be easier to remove electrons from the ion because it needs to lose less electrons than it needs to gain to have a full shell (needs to lose 2, but gain 4). This is the opposite for S because it needs to gain 2, but lose 6.

`S^(2-)` already has a full valence shell so it would be really hard to remove an electron from it.