Why does Slightly decrease in EI2 between nitrogen and oxygen influence ionisation energies?

- Oxygen has 1 more proton than nitrogen, electron removed is in 2p sub shell - Electrons removed from nitrogen is from orbital that contains an unpaired electrons - Electrons removed from oxygen is from orbital that contains a pair of electrons - Extra repulsion between pair of electrons in this orbitals results in less energy being needed to remove an electron. - IE1 for oxygen is lower because of spin pair repulsion