CBSE Tuts

CBSE Maths notes, CBSE physics notes, CBSE chemistry notes

NEET Chemistry Notes Some Basic Principles and Techniques – Isomerism

NEET Chemistry Notes Some Basic Principles and Techniques – Isomerism

Isomerism

Isomerism

The compound having same molecular formula but differ in properties are known as isomers and the phenomenon is called isomerism.

Structural Isomerism

In this type of isomerism, compounds have same molecular formula but different structures.

  • Chain Isomerism

It arises when two or more compounds have similar molecular formula but different carbon skeletons, e.g.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 1

  •  Position Isomerism

It arises when two or more compounds have same molecular formula but different position of functional groups or substituents
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 2

  • Functional Isomerism

It arises when two or more compounds have the same molecular formula but different functional group, e.g. C3H60 represents an aldehyde and a ketone as:
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 3

  • Metamerism

It arises due to different alkyl groups on either side of the same functional group in the molecule

e.g.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 4

  • Tautomerism

It is a special type of functional isomerism arises in carbonyl compounds containing NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 10 atom.

e.g.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 5
Stereoisomerism

The compounds having same molecular formula but different spatial arrangement of atoms or groups are called stereoisomers and the phenomenon is called stereoisomerism.

Stereoisomerisnf is of three types:

  • Geometrical Isomerism

The isomers having same molecular formula but different spatial arrangement of atoms about the double bond are known as geometrical isomers and this phenomenon is called geometrical isomerism, e.g.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 6

  • Optical Isomerism

Compounds having similar physical .and chemical properties but differ only in behaviour towards plane polarised light are called enantiomers and show optical isomerism
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 7

  • Conformational Isomerism

In conformational isomerism because of the free rotation of carbon-carbon single bond, different arrangement of atoms in space are obtained.

Fission of a Covalent Bond

Carbon forms a number of different types of organic compounds because it forms covalent bonds with itself and with other elements like Ii, O, N, X, P and S etc., in a variety of ways. For better understanding of organic chemistry, it is necessary to understand some basic terms, processes and basic principles. The organic reactions begin with the breakage of covalent bond.

Homolytic Fission

In this, one of the electrons of the shared pair in a covalent bond goes with each of the bonded atoms. Generally, homolytic fission takes place in non-polar covalent molecules in the presence of sunlight or high temperature.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 8

Heterolytic Fission

In this, the bond breaks in such a fashion that the shared pair of electrons goes with one of the fragments, arising positive and negative charges.
NEET Chemistry Notes Some Basic Principles and Techniques - Isomerism 9
Heterolytic fission generally takes place in polar covalent molecules but in non-polar molecules, it takes place in the presence of catalyst like AlC13 (anhyd.), FeC13 (anhyd.) etc.

Reaction Intermediates

Most of the chemical reactions require certain chemical species to occur. These species are generally short lived, highly reactive and are called reactive intermediates, e.g. free radicals, carbocations, carbanions, carbenes, nitrenes, etc.

ChemistryPhysicsBiology