Homologous Series | Chemistry | CSEC CXC lessons online – Study Guide

The Homologous Series - organic chemistry

The millions of organic compounds existent can be broken down into categories or series, due to their properties, called homologous series.

A Homologous series is a group of organic compounds which are classified together due to their similarities in properties i.e. chemical behavior etc

N.B. Hydrocarbons are organic compounds containing hydrogen and carbon ONLY

Hydrocarbons comprise of the following:



Alkanes make up  the simplest homologous series. They are saturated i.e. they contain c-c bonds only. They are relatively unreactive

General formula: Cn H2n +2

First four members

Methane  C1 H4 

Ethane      C2 H6 

Propane   C3 H8 

Butane      C4 H10 



Alkenes contains carbon to carbon double bonds and are unsaturated


General formula: Cn H2n

First four members

Methene  C1 H2

Ethene      C2 H4

Propene   C3 H6

Butene      C4 H8