Chirality refers to the configuration, or "handedness," of an asymmetric chemical compound. A chiral object is not superimposable on its mirror image, meaning they cannot be laid one on top of the other so that all like parts coincide. Stereochemistry is concerned with the structures of molecules in three dimensions. Isomers are different compounds with the same molecular formula. A molecular formula is a formula that indicates the number of atoms of each type of element in a molecule.

At A Glance

  • Molecules can exist as constitutional isomers or stereoisomers. The stereochemistry of a chirality center can be determined using the Cahn-Ingold-Prelog method.
  • The Cahn-Ingold-Prelog system is used to identify enantiomeric structures by assigning a priority based on the atomic number to each atom attached to a single tetrahedral atom with four different groups.
  • Molecules with a chirality center can exist as a pair of stereoisomers called enantiomers that have identical physical properties. However, in a chiral environment (such as polarized light), a pair of enantiomers will exhibit different properties, such as equal but opposite rotation of polarized light.
  • Pairs of isomers can be enantiomers, diastereomers, or meso. If a compound has a plane of symmetry and a chirality center, it is a meso compound. Enantiomers are stereoisomers that are nonsuperposable mirror images of each other, and diastereomers are stereoisomers that are nonsuperposable and not mirror images of each other.
  • Fischer projections are another way of visually representing chirality.