This video lecture from Macromolecules (F.Sc. second year Chemistry) covers addition polymerization which takes place in three steps, initiation, propagation and termination. Free radicals are formed in the initiation step which initiates a chain reaction called propagation until terminated by another free radical or chain. Most alkenes (compounds with double bonds) polymerize in this manner. 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.