This video lecture from Periodic Classification of Elements and Periodicity (F.Sc. second year Chemistry) covers: A detailed discussion of Ionic, Covalent and Vander Waals radii. The nuclear charge within periods and the extra orbit in every period and the similarity of behavior that is followed within the periodic table in groups and in periods. 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.