Aliphatic and aromatic compounds

In organic chemistry, hydrocarbons can be divided into aromatic compounds which contain aromatic rings, also known as benzene rings, and aliphatic compounds which do not.

An aromatic ring is a cylic arangement of six carbon atoms, in which delocalised electrons in the unused p-orbitals overlap to form a ring shaped bond above and below the planar ring, making it more stable than would be expected. The simplest aromatic compound is benzene, which consists of exactly one aromatic ring and is thus more stable than would otherwise be expected.

Examples: - Methane is an aliphatic compound, and contains no aromatic rings. - Benzene is an aromatic compound, as it is an aromatic ring. - Toluene is an aromatic compound, as it contains an aromatic ring bonded to a methyl group.