Isomers

What are isomers?

Two compounds with the same molecular formula. Given this broad definition, there are many types of isomers:

• Structural isomers:
  Two compounds with the same molecular formula but a differing arrangement of atoms. Structural isomers can also be called constitutional isomers.
• Stereoisomers:
  Two compounds with the same molecular formula and the same order of atom attachment, but a differing spatial arrangement of atoms.
  • Enantiomers:
    Stereoisomers that are mirror images of each other and are identified by R and S nomenclature and are optically active.
  • Diastereomers:
    Stereoisomers that are not mirror images of each other.
  • Geometric isomers:
    Stereoisomers that differ in the arrangements of atoms in molecules with double bonds and are identified by cis-/trans- designations.