Combining hydrogen and carbon produces a group of organic compounds called hydrocarbons. Depending on the specific molecular formula, there can be many different types of hydrocarbons, such as the fuels propane and octane. The simplest hydrocarbon is methane, which has the chemical formula CH4.
The four classes of hydrocarbons are alkanes, alkenes, alkynes and aromatics. Alkanes are made up of single-bonded hydrogen and carbon atoms. These organic compounds usually have molecular formulas given by CnH2n+2, where n is given as an integer. Alkenes have a carbon-to-carbon double bond while alkynes exhibit triple bonds. Aromatic hydrocarbons include compounds that contain a benzene ring.
In nature, hydrocarbons are present in plants, natural rubber and in fossil fuels. Natural rubber consists of molecules that have chained units bonded together to form a polymer.