Stereoisomers are molecules that have the same molecular formula and the same sequence of bonded atoms (connectivity) but differ in the three-dimensional spatial arrangement of their atoms

. This means that while the atoms are connected in the same order, their orientation in space is different, leading to distinct chemical and physical properties. There are two main types of stereoisomers:

• Enantiomers : These are pairs of stereoisomers that are non-superimposable mirror images of each other, much like left and right hands. Enantiomers have identical physical properties except for the direction in which they rotate plane-polarized light and how they interact with other chiral molecules. They often differ significantly in biological activity

• Diastereomers : These stereoisomers are not mirror images of each other and have different physical and chemical properties. Diastereomers can occur when molecules have two or more chiral centers and include geometric isomers such as cis-trans isomers around double bonds or rings

Stereoisomerism is crucial in chemistry and biology because the different spatial arrangements can lead to different behaviors in chemical reactions and biological systems. For example, one enantiomer of a drug may be therapeutic while its mirror image may be harmful

. In summary, stereoisomers share the same molecular formula and connectivity but differ in how their atoms are arranged in three-dimensional space, leading to different properties and biological effects