What is a homologous series? Explain with an example.

Homologous series

• “A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series”
• A homologous series is a series of compounds of carbon that have different numbers of carbon atoms but have the same functional group.
• Due to the different numbers of carbon atoms, the physical properties of the compounds in this series are not the same.

Example of homologous series

• Methane $\left({\mathrm{CH}}_4\right)$, ethane $\left({\mathrm{C}}_2{\mathrm{H}}_6\right)$, propane $\left({\mathrm{C}}_3{\mathrm{H}}_8\right)$ and butane $\left({\mathrm{C}}_4{\mathrm{H}}_{10}\right)$ belong to the homologous series of alkanes.
• The general formula of this homologous series of an alkanes is ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$