There are three types of structural isomers: chain isomers, functional group isomers and positional isomers. Chain isomers have the same molecular formula but different arrangements or branches. Functional group isomers have the same formula but different functional groups.
In fact, the formula for all alkanes is CnH2n + 2. You have already seen that butane (C4H10) has an isomer, 2-methylpentane. These are the only two isomers of this molecule.
Butane and isobutane (C4H10) are structural isomers of each other. Pentan-1-ol, pentan-2-ol, and pentan-3-ol are structural isomers that exhibit position isomerism. Cyclohexane and hex-1-ene are examples of functional group structural isomers.
Learn more about structural isomers here:
