Group 15 Elements

Both and give With excess of water.

The atoms having half-filled and fully filled orbitals are comparatively more stable, hence more energy is required to remove the electron from such atoms. Therefore group 15 have more I.E. than gp. 16 elements.

In phosphorous the 3J-orbitals are available. Hence phosphorus can form pentahalides also but nitrogen cannot form pentahalide due to absence of d-orbitals.