Answer:
Molecules that have the same chemical formula (same numbers of each atom) but different three-dimensional shapes are called Stereoisomers.
Step-by-step explanation:
Stereoisomerism is a phenomenon in which molecules have same molecular formula but have different arrangement of atoms or group of atoms in space. It is further classified as;
i) Geometrical Isomerism:
In this class of isomerism the groups or atoms about the double bond occupies different region in space. It is also called as cis-trans isomerism.
ii) Optical Isomerism:
In this class the molecules having same molecular formula differ in their interaction towards plane polarized light.