A pair of enantiomers is a pair of molecules that are non-superimposable
mirror images of each other. Shown here are a pair of imaginary enantiomers,
with different colors representing different atoms or groups attached to
the stereogenic carbon atom. The point being illustrated is that a tetrahedral
carbon atom with four different atoms or groups attached will almost always
be chiral. This is a consequence of geometry. Two enantiomers will have
identical properties unless those properties are measured in a chiral way
(i.e. rotation of plane polarized light, taste, smell, etc.). Recall that
each enantiomer will rotate plane polarized light an equal magnitude, but
opposite direction.