# How do structural isomers arise?

Structural isomerism arises from differing connectivity. An organic formula of ${C}_{4} {H}_{10}$ can give rise to two structural isomers: $\text{n-butane,}$ ${H}_{3} C - C {H}_{2} C {H}_{2} - C {H}_{3}$; and $\text{methylpropane or isobutane,}$ ${H}_{3} C - C H \left(C {H}_{3}\right) C {H}_{3}$.
As the organic formula becomes larger, the number of possible isomers necessarily increase. ${C}_{5} {H}_{12}$ can generate 3 structural isomers. And $\text{hexane}$, ${C}_{6} {H}_{14}$ can generate 5 structural isomers. And so on...........the larger alkanes can generate many structural isomers.