The electronic configuration of atom is one of the important factor which affects the value of ionisation potential and electron gain enthalpy.

Explanation

(i) Electronic configuration of an atom affects the value of ionization potential and electron given enthalpy.
(ii) Half filled valence shell electronic configuration and completely filled valence shell electronic configuration are more stable than partially filled electronic configuration.
(iii) For eg Beryllium `(Z=4)1s^(2),2s^(2)` (completely filled electronic configuration) Both beryllium and nitrogen have high ionization energy due to more stable nature.
(iv) In the case of beryllium `(1s^(2)2s^(2))` , nitrogen `(1s^(2),2s^(2),2p^(3))` the addition of extra electron will disturb their stable electronic configuration and they have almost zero electron affinity
(v) Noble gases have stable `n^(2),np^(6)` configuration and the addition of further electron is unfavorable and they have zero electron affinity.