(i) Increases down a group
Reason : At each succeeding element down a group the number of shells increases, so the distance of the valence shell from the nucleus increases, the effective nuclear force of attraction decreases on the last shell, so it becomes easy for the atom to lose electrons.
(ii) Decreases in a period from left to right.
Reason : As the effective nuclear charge on the valence shell electron increases, the attraction between the valence electron and nucleus increases, so it becomes difficult to lose electrons.
