Naming Enantiomers by the R,S System

How do we name the different stereoisomers of a compound like 2-bromobutane so that we know which one we are talking about We need a system of nomenclature that indicates the arrangement of the atoms or groups around the asymmetric center. Chemists use the letters R and S for this purpose. For any pair of enantiomers with one asymmetric center, one member 

How the relative priorities of groups is determined is also discussed in Section 5.7. 

The greater the atomic number of the atom directly attached to the asymmetric center, the higher the priority of the substituent. 

If the atoms attached to the asymmetric center are the same, the atoms attached to those atoms are compared. 

Clockwise specifies R if the lowest priority substituent is on a hatched wedge. 

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