Enantiomers and diastereomers are two types of stereoisomers, which are molecules with the same molecular formula and sequence of bonded atoms but differ in their three-dimensional arrangement in space.Enantiomers are non-superimposable mirror images of each other. They have the same physical and chemical properties, except for their interaction with plane-polarized light and their interaction with other chiral molecules. Enantiomers have opposite configurations at all chiral centers.Diastereomers, on the other hand, are stereoisomers that are not mirror images of each other. They have different physical and chemical properties and can have different configurations at one or more chiral centers.A molecule is considered chiral if it cannot be superimposed on its mirror image. Chiral molecules usually have at least one chiral center, which is a carbon atom bonded to four different groups. To determine if a molecule is chiral or achiral, you can look for the presence of chiral centers and check if the molecule has a plane of symmetry. If a molecule has a plane of symmetry, it is achiral.For example, consider the chiral molecule 2-butanol CH3-CH OH -CH2-CH3 . It has a chiral center at the second carbon atom, which is bonded to four different groups: a hydrogen atom, a hydroxyl group, a methyl group, and an ethyl group. Its enantiomers are R -2-butanol and S -2-butanol, which are non-superimposable mirror images of each other.If we consider 2,3-dichlorobutane CH3-CHCl-CHCl-CH3 , it has two chiral centers at the second and third carbon atoms. There are four possible stereoisomers for this molecule: R,R -2,3-dichlorobutane, S,S -2,3-dichlorobutane, R,S -2,3-dichlorobutane, and S,R -2,3-dichlorobutane. The first two are enantiomers, and the last two are also enantiomers. However, the R,R and R,S forms, as well as the S,S and S,R forms, are diastereomers since they are not mirror images of each other.