This irregularity (as in ionisation
enthalpies) arises mainly from the extra stability of empty, half-filled
or filled f subshell Thus, the formation of Ce
IV is favoured by its
noble gas configuration, but it is a strong oxidant reverting to the
common +3 state The E
o value for Ce
4+/ Ce
3+ is + 1 74 V which
suggests that it can oxidise water