Hydrocarbons are any organic compounds that contain only carbon and hydrogen. Their general molecular formula is CxHy. There are several categories of hydrocarbons:
1. Alkanes have the general formula CnH2n+2. All of the carbon-to-carbon bonds in an alkane are single bonds.
2. Alkenes have the general formula CnH2+n. There is one carbon-to-carbon double bond in an alkene. All of the other carbon-to-carbon bonds in an alkene are single bonds.
3. Alkynes have the general formula CnH2n. There is one carbon-to-carbon triple bond in an alkyne. All of the other carbon-to-carbon bonds in an alkyne are single bonds.
4. Aromatic hydrocarbons are all derivatives of benzene (C6H6), in which the six carbons form a ring with one hydrogen bonded to each carbon.