Rucete ✏ Chemistry In a Nutshell
Isomerism
Isomerism happens when two organic compounds have the same molecular formula but different structural formulas. #
Isomerism is classified into two categories.
Structural Isomerism
and
Stereoisomerism
Let me give you a brief.
Structural Isomerism
This occurs as compounds with different structural for structural formulae.
1. Chain and branched-chain isomers
These compounds have different carbon skeletons.
2. Positional isomers
These have the same carbon skeleton. However, they have the functional group is attached to different
positions on their carbon skeleton.
3. Functional group isomers
These occur since isomeric molecules have different physical and chemical properties when they belong to different homologous series.
Example
Aldehydes and Ketones
They have the same number of carbon atoms.(CnH2nO)
However, they show difference.
Propanal : CH3CH2CHO
Propanone: CH3COCH3
There are other examples : Alcohols and Ethers, Alkenes and Cyclic Alkanes, Alkynes and Cyclic Alkenes, Carboxylic Acids and Esters
Stereoisomerism
The different spatial arrangements of atoms in a molecule cause this form of isomerism.
1. Geometric isomerism
This happens in compounds where the presence of a C=C double bond or a C—C ring structure prevents free rotation. Geometric isomers are also known as cis- and trans-isomers. They have atoms or groups of atoms that are arranged in a particular spatial structure.
2. Optical isomerism
This arises when four different atoms or groups of atoms are connected to the same carbon.
These characteristics are depicted in the image above. Since they cannot be superimposed, after reflection in a plane of symmetry and rotating the result 180 degrees, you end up with a new molecular structure.