Question

Oxygen has lower ionization enthalpy than nitrogen and fluorine. Why​

Answer 1

Answer:

It is due to an electron being added to an already half full orbital in oxygen, which results in electron electron repulsion, which will lower the ionisation energy.

Answer 2

Explanation:

Oxygen has low ionisation energy (than that of nitrogen). It is due to an electron being added to an already half full orbital in oxygen, which results in electron electron repulsion, which will lower the ionisation energy. ... As Nitrogen is more stable, therefore it is much difficult to remove the valence electron.