This video lecture from Chemical Bonding (F.Sc. First Year Chemistry) covers the concept of first, second and third Ionization energy and the reasons why higher Ionization energies are larger than the first ionization energy. The concept of estimation of valency of the element with the gap of the ionization energies are also discussed. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.