Isomer

The term isomer comes from the Greek ισο (iso-) which means equally or the same and μέρος (meros) which means is a part or sharing. This word is ambiguous in an energy context. It may refer to:

• Nuclear isomer: two different nucleus' with the same number of protons and neutrons, but they behave differently.
• Chemical isomer: two different molecules with the same number and type of atoms, but different configurations and properties.