For two compounds,do the compounds have the same molecular formula?
This diagram created using Inspiration® by Inspiration Software, Inc.

This chart is modified from http://www.chem.ucalgary.ca/courses/351/Carey/Ch07/ch7-1.html.

Formal definitions of the types of isomers are given plus more examples of molecules in Chime.

Why the big interest in isomers?  

In general, isomers have a difference in physical, chemical, and/or biological properties.  The chain length, position of groups, and the type of functional groups change the properties and the chemical reactivity of isomers.

Optically active isomers or enantioners have the same physical properties, except that they rotate polarized light in opposite directions.  However, their reactivity in biochemical systems is drastically different - one isomer reacts and the other does not!

The differences in various properties allows isomers to be separated in most cases.  Only conformational isomers, differences due to free rotation about single bonds, cannot be separated.

These aspects are examined in greater detail in organic chemistry and biochemistry.

Return to Structure and Bonding: More About Isomers page.