Comparison of the molecules structures of a primary, secondary and tertiary amine (respectively from left to right at the start and end of the clip). Atoms are colour-coded spheres: nitrogen (blue), carbon (black) and hydrogen (white). An amine is an organic molecule in which a nitrogen atom carries a lone pair of electrons, unlike in other nitrogen-containing compounds such as amides, in which the lone pair is delocalised through nearby bonds. The primary, secondary and tertiary classification refers to the number of carbon atoms bonded to the nitrogen atom. This affects the chemistry of the compound. These three molecules are isomers, all having the same formula: C3H9N. However they are different chemicals with different properties. From left to right they are: propylamine (a primary amine), ethylmethylamine (secondary) and the tertiary amine trimethylamine.