Hydrocarbons are compounds that only contain carbon and hydrogen. Hydrocarbons
can be classified further by the type of bonds they contain. If a hydrocarbon contains only
single bonds, it is an alkane. If it contains one or more carbon-carbon double bonds, it is
classified as an alkene. If it contains one or more triple bonds between two carbon atoms, it
is an alkyne. If it contains a benzene ring, it is considered aromatic. (If it does not contain a
benzene ring, it is aliphatic. Therefore, alkanes, alkenes, and alkynes are all aliphatic
hydrocarbons.) These types of compounds react in different ways, so it is possible to
distinguish between them using experimental tests.