Stereoisomers
- Two molecules with the same molecular formula but different structural formula are called isomers. Due to different structural formulas of isomers, they show different chemical and physical properties.
- Isomers can be classified as structural isomers and stereoisomers. This classification is on the basis of arrangement of bonded atoms in the 2D and 3D space around the central atom.
- The structural isomers have the same molecular formula but different arrangement of bonded atoms. Thus, two structural isomers must exhibit different chemical and physical properties.
- Structural isomerism can be further classified as: Chain isomerism, functional group isomerism, metamerism, tautomerism and position isomerism.
- Substances having the same molecular formula and same structural formula but differ in the spatial arrangement of atoms or groups of atoms are known as stereoisomers.
- Enantiomers: Stereoisomers which are non-superimposable mirror images of each other are called enantiomers. They are classified as ‘d’ and ‘l’ isomers.
- Diastereomers: The optical isomers which are neither mirror image non-superimposable to each other are called diastereomers.
Stereoisomers Questions
Question 1: Stereoisomers are the Substances having the same molecular formula and same structural formula but differ in the ___________ of atoms.
(a) Bonds
(b) Spatial arrangement
(c) Molecular formula
(d) Masses
Solution : Substances having the same molecular formula and same structural formula but differ in the spatial arrangement of atoms.
Answer : (b)
Question 2: Stereoisomers which are non-superimposable mirror images of each other are called ___________.
(a) Diastereoisomers
(b) Racemic mixtures
(c) Enantiomers
(d) All the above
Solution : Stereoisomers which are non-superimposable mirror images of each other are called enantiomers.
Answer : (c)
Question 3: The optical isomers which are neither mirror image nor superimposable to each other are called ____________.
(a) Diastereoisomers
(b) Racemic mixtures
(c) Enantiomers
(d) All the above
Solution : The optical isomers which are neither mirror image nor superimposable to each other are called diastereomers.
Answer : (a)
Frequently Asked Questions
What is a Stereoisomer example?
Stereo-isomers are compounds with the same molecular formula but different atomic arrangement in three dimensional space. Stereo-isomers can be of two types
Geometrical isomers- Also known as diastereomers or cis-trans isomers, these isomers results from different arrangement of atoms in molecules having double bond or ring structure. For example, cis-2-butene and trans-2-butene.
In cis-2-butene, the methyl groups are on one side of double bond and hydrogen on the other side.
In trans-2-butene, the two methyl groups are on opposite sides around the double bond and so are two hydrogen atoms.
Optical isomers- Also known as enantiomers, these isomers have structures which are mirror images of each other and can’t be superimposed over each other in any orientation.
How many stereoisomers are possible for the compound?
1,2dibromocyclohexane
What are stereoisomers and enantiomers?
Stereo-isomers are compounds with the same molecular formula but different atomic arrangement in three dimensional space. Stereoisomers are of two types- Geometrical isomers or diastereomers and optical isomers or enantiomers.
Enantiomers are one type of stereo-isomers. These isomers have structure, which are non-superimposable mirror images of each other in every possible orientation.
How many stereoisomers are there?
Stereoisomers are of two types-
Geometrical isomers- Also known as cis-trans isomers, these isomers results from different arrangement of atoms in molecules having double bond or ring structure. For example, cis-2-butene and trans-2-butene.
In cis-2-butene, the methyl groups are on one side of double bond and hydrogen on the other side.
In trans-2-butene, the two methyl groups are on opposite sides around the double bond and so are two hydrogen atoms.
Optical isomers- These isomers have structures which are mirror images of each other and can’t be superimposed over each other in any orientation.