Isomerism types characteristic of alkanes.

Alkanes usually show structural and optical isomerism.

Structural isomers are molecules with: the same molecular formula; various structural formulas. The structural isomers of alkanes have: the same number of carbon and hydrogen atoms; different arrangement of carbon and hydrogen atoms.

Optical isomers are stereoisomers formed when there are asymmetric centers, for example carbon with four different groups attached to it. Enantiomers are two optical isomers (i.e. isomers that are reflections of each other). Each stereocenter in one isomer has an opposite configuration in the other. Compounds that are enantiomers of each other have the same physical properties, with the exception of the direction in which they rotate polarized light and how they interact with different optical isomers of other compounds.