In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon, and thus are group 14 hydrides. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls. Compounds of hydrogen and carbon are called hydrocarbons.
Homologous series of Alkanes: CnH2n+2
Homologous series of Alkenes: CnH2n
Homologous series of Alkynes: CnH2n-2
Structure of the first member of each series:

Addition reaction or hydrogenation converts alkenes into alkanes.
