Question

What is isomerism? Draw the structural isomers of butane and pentane.

Answer 1

Hint: Isomerism is the phenomenon of molecules with the same molecular formula, but with different structures. Alkanes are the saturated hydrocarbons and can exhibit chain isomerism. Chain isomerism is one of the classifications of structural isomerism.

Complete answer:
Chemical compounds are classified into functional groups based on the groups present in it. hydrocarbons are the chemical compounds that consist of only carbon and hydrogen atoms. Alkanes, alkenes, and alkynes belong to hydrocarbons.
The compounds with the same molecular formula, but with different structures are known as structural isomers and the phenomenon is known as structural isomerism.
Alkanes are the saturated hydrocarbons with the general molecular formula of $C_n{H}_{2n+2}$ , where n is the number of carbon atoms. Alkanes can exhibit only chain isomerism which means there is a difference in carbon skeleton.
Butane is an alkane with molecular formula of $C_4{H}_{10}$ , it can exist in two different structural isomers.
The structure of n-butane $C{H}_{3}C{H}_{2}C{H}_{2}C{H}_3$
The structure of $2-$ methyl propane $C{H}_{3}CH\left(C{H}_3\right)C{H}_3$
Pentane is an alkane with the molecular formula of $C_5{H}_{12}$ , it can exist in three different structural isomers. They are n-pentane, iso-pentane, and neopentane.
The structure of n-pentane is $C{H}_{3}C{H}_{2}C{H}_{2}C{H}_{2}C{H}_3$
The structure of iso-pentane is $C{H}_{3}CH\left(C{H}_3\right)C{H}_{2}C{H}_3$
The structure of neopentane is $C{\left(C{H}_3\right)}_4$ .

Note:
Structural isomerism was classified into five types, they are chain isomerism, position isomerism, functional isomerism, metamerism and tautomerism. As the alkanes do not have any functional group or unsaturation bonds, these compounds can exhibit only chain isomerism.