Homologous series- Carbon atoms can be linked together to form chains of varying lengths. These chains can be branched also. In addition hydrogen atom or other atom on these carbon chains can be replaced by any of the functional groups. The presence of a functional group such as alcohol decides the properties of the carbon compound, regardless of CH3OH, C2H5OH, C3H7OH and C4H9OH are all are very similar. Hence , such a series of compounds in which the same functional group substitutes for hydrogen in a carbon chains is called homologous series.
A)HCOOH – Methanoic acid B)CH3COCH3 – Propanone
CH3COOH – Ethanoic acid CH3COCH2CH3 – Butan-2-one
CH3CH2COOH – Propanoic acid CH3COCH2CH2CH3– Pentane-2-one
CH3CH2CH2COOH – Butanoic acid CH3COC4H9 – Hexane-2-one
CH3CH2CH2CH2COOH -Pentanoic acid CH3COC5H11 – Heptane-2-one
C)HCHCH2 – Ethene
CH3CHCH2 – Propene
CH3CH2CHCH2 – But-1-ene
CH3CH2CH2CHCH2 – Pent-1-ene
CH3CH2CH2CH2CHCH2 – Hex-1-ene