# Why are alkenes, alkanes, and alkynes with 5 carbon atoms each not considered isomers?

Apr 15, 2018

See below...

#### Explanation:

For the compounds to be isomers they must have identical condensed formula.

Alkane with $n$ $C$ atoms : ${C}_{n} {H}_{2 n + 2}$

Alkene with $n$ $C$ atoms : ${C}_{n} {H}_{2 n}$

Alkyne with $n$ $C$ atoms : ${C}_{n} {H}_{2 n - 2}$

The compounds clearly differs in the number of $H$ atoms per molecule and hence cannot be considered as isomers.