The difference between primary, secondary, and tertiary amines lies in the number of carbon atoms directly attached to the nitrogen atom in their molecular structure. 1. Primary amine: In a primary amine, the nitrogen atom is bonded to one carbon atom and two hydrogen atoms. The general formula for a primary amine is RNH2, where R is an alkyl or aryl group.Example: Methylamine CH3NH2 2. Secondary amine: In a secondary amine, the nitrogen atom is bonded to two carbon atoms and one hydrogen atom. The general formula for a secondary amine is R2NH, where both R groups can be the same or different alkyl or aryl groups.Example: Dimethylamine [ CH3 2NH]3. Tertiary amine: In a tertiary amine, the nitrogen atom is bonded to three carbon atoms and has no hydrogen atoms directly attached to it. The general formula for a tertiary amine is R3N, where all three R groups can be the same or different alkyl or aryl groups.Example: Trimethylamine [ CH3 3N]