Alkane
![Different C4 alkanes and cycloalkanes (left to right): n-butane and isobutane are the two C4H10 isomers; cyclobutane and methylcyclopropane are the two C4H8 isomers. Bicyclo[1.1.0]butane is the only C4H6 compound and has no isomer; tetrahedrane (below) is the only C4H4 compound and also has no isomer.](/uploads/202501/30/Saturated_C4_hydrocarbons_ball-and-stick1003.png)
In organic chemistry, an alkane, or paraffin (a historical name that also has other meanings), is a saturated hydrocarbon. Alkanes consist only of hydrogen and carbon atoms and all bonds are single bonds. Alkanes (technically, always acyclic or open-chain compounds) have the general chemical formula CnH2n+2. For example, methane is CH4, in which n = 1 (n being the number of carbon atoms). Alkanes belong to a homologous series of organic compounds in which the members differ by a molecular mass of 14.03 u (mass of a methylene group, —CH2—, one carbon atom of mass 12.01 u, and two hydrogen atoms of mass ~1.01 u each). There are two main commercial sources: petroleum (crude oil) and natural gas.