Nomenclature of stereo-isomers [R-S & E-Z]

In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, but the bond connections or their order differs. By definition, molecules that are stereoisomers of each other represent the same structural isomer.

Since their structural formulae are same, simple IUPAC nomenclature rules give same name to both the stereo-isomers. To differentiate them further few rules have been introduced under the name "Nomenclature of Stereo-isomers".  Course includes

1. Cahn-Ingold-Prelog (CIP) priority rules; This is the common step towards both E-Z and R-S Nomenclature. Here we differentiate the groups attached to the stereocenter based on atomic number. The CIP sequence rules contribute to the precise naming of every stereoisomer of every organic molecule

2. E-Z nomenclature of alkenes; This nomenclature is specifically applicable to the double-bonded stereocenters. The need of E-Z nomenclature becomes significant where cis trans nomenclature fails. Here we have the cases of geometrical isomerism.

3. R-S nomenclature of 'sp3' hybridized carbon; This nomenclature is applicable for tetrahedral stereocenters. Here we have the cases of enantiomers (optical isomers).