This video lecture from Fundamental Principles of Organic Chemistry (F.Sc. second year Chemistry) covers Stereo Isomerism. In this type of isomerism, 2 different molecules may have same molecular formula and even same structure but owing to different orientation in 3d space, they exist as different molecules or stereo isomers of each other. The second type of stereo isomers are optical isomers which exist because of a chiral carbon atom (with different groups on each side) bonding in different ways. These isomers are mirror images of each other and give special optical characteristics to the material in which they are contained. These materials deflect (or bend) the path of a polarized light falling on them. 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.