Hydrocarbons

Hydrocarbons are a class of molecules that contain only carbon and hydrogen atoms. Some of them make very good fuels. Gasoline contains a mixture of hydrocarbons. Unsaturated hydrocarbons, which contain one or more double bonds, are useful chemicals for many reactions.

Linear saturated hydrocarbons

The simplest hydrocarbons are linear molecules in which each carbon atoms is bonded to two other carbons atoms, in a linear fashion, except for the carbon atoms at the ends, which are only bonded to one other carbon atom. Saturated hydrocarbon names generally end with the suffix "ane" which distinguishes them from unsaturated hydrocarbons, which end with the suffix "ene".

Linear saturated hydrocarbons are also referred to as paraffins or alkanes. Their general formula is C_nH_n+2.

Some example alkanes

Name	Formula	CnH2n
Methane	CH4	CH4
Ethane	CH3–CH3	C2H6
Propane	CH3–CH2–CH3	C3H8
Butane	CH3–(CH2)2–CH3	C4H10
Pentane	CH3–(CH2)3–CH3	C5H12
Hexane	CH3–(CH2)4–CH3	C6H14
Heptane	CH3–(CH2)5–CH3	C7H16
Octane	CH3–(CH2)6–CH3	C8H18
Nonane	CH3–(CH2)7–CH3	C9H20
Decane	CH3–(CH2)8–CH3	C10H22

Linear unsaturated hydrocarbons

Unsaturated hydrocarbons are useful precursor molecules for many reactions. Because they contain one or more double bonds, a large variety of chemical transformations are possible. Unsaturated hydrocarbons generally end with the "ene" suffix, although common names are sometimes used instead of the IUPAC designation. In addition, a numerical prefix is used to indicate the position of the double bond(s).

Linear unsaturated hydrocarbons are also called olefins or alkenes.

Hydrocarbon name	Chemical Formula
Ethene	CH2-CH2
Propene	CH2-CH-CH3
1-Butene	CH2-CH-CH2-CH3
2-Butene	CH3-CH-CH-CH3
1-Pentane	CH2-CH-(CH)2-CH2-CH3