» This article is about the chemical concept. For "isomerism" of atomic nuclei, see nuclear isomer. In chemistry, isomers are compounds with the same molecular formula but different structural formulae Isomers don't necessarily share similar properties unless they also have the same functional groups. This shouldn't be confused with a nuclear isomer, which involves a nucleus at different states of excitement. There are many different classes of isomers, like stereoisomers, enantiomers, geometri… (More on Isomers)