Question

Among N and O which has high first ionization enthalpy and why

Answer 1

oxygen, the element next to nitrogen has slightly smaller ionisation enthalpy as compared to that of Nitrogen. it is due to the fact that the electronic configuration of Nitrogen atom(1s²,2s²,2px¹,2py¹,2pz¹),in which 2p-orbital is half filled, is more stable than that of oxygen (1s²,2s²,2px²,2py¹,2pz¹). therefore, ionisation enthalpy of Nitrogen is more than that of oxygen.