Organic

• stereoisomerism: same molecular formula but different spatial arrangement of atoms
• stereoisomerism happens with unsymmetrical carbons with chiral centres
• enantimor: 2 possible isomers (mirror images) that form because of chiral centres
• each enantimor causes the rotation of plane polarised light by 90 degrees in the opposite direction
• racemic mixture: contains equal amounts of enantimors
• racemic mixtures are optically inactive -> opposite directions of rotation by each enantimor cancels out
• optical isomers can form because of nucleophilic addition reactions - nucleophile attacks a carbonyl group from above or below c=o bond