Why are certain compounds called hydrocarbons?

Hydrocarbons are a group of compounds made up of carbon and hydrogen. The general formula of homologous series of alkanes is CnH2n+2, of alkenes is CnH2n and of alkynes is CnH2n-2. The reaction that converts alkenes to alkanes is an addition reaction. It is as follows: CH2=CH2 + H2 --Ni catalyst--> Heat CH3-CH3. For this reaction catalysts like Raney Ni, Pt and Pd can be used.