A homologous series may be defined as a family of organic compounds having the same functional group,and the successive(adjacent) members of which differ by a CH
unit or 14 mass units.
Two consecutive members of homologous series of Aldehydes: CH
CHO and C
A carbon compound is made up of two parts: R-F,where R is the hydrocarbon part and F is the functional group part.
So,this R (hydrocarbon) part determines the physical properties of a compound and the F (functional group) part determines the chemical properties of the compound.