(i) Screening effect: The inner electrons between valence electron and nucleus shield’s the valence electron from nucleus; it is called shielding effect.
(ii) Penetration effect: Due to shape of the orbital, s-electron penetrates nearer to the nucleus than p, d or electrons and more tightly held.
(iii) Metallic character: Lower the ionization energy, more will be tendency to lose electron, higher will be metallic character.
