Butane and ethyl pentane are alkanes because they contain only single bonds between their carbon atoms. 2,3-dimethyl hexane is also an alkane, with methyl groups attached to the second and third carbon atoms of the hexane structure. Alkanes are highly combustible and those with fewer than five carbon atoms are gases used as fuels, while gasoline contains alkanes from pentane to decane. Alkanes are valuable components of many products and are too important as resources to be used only for fuel.