Question

Why does N have positive EGE?

Answer 1

The Main Concept Behind these Statements is the Extra Stability of half filled p orbitals.

Nitrogen has a electronic configuration of 1s^2,2s^2,2p^3. As the p orbital is half filled,it has an extra stability than other elements next to it. Due to this , to add electron to nitrogen energy is required,hence it has a positive value of electron gain enthalpy .

Oxygen has a configuration of 1s^2,2s^2,2p^4. Releasing one electron give Oxygen a more stable half filled 2p orbital whereas with Nitrogen removing a electron makes its configuration less stable than the previous half filled 2p config. So 1st ionisation enthalpy of Oxygen is Less than Nitrogen