🔴 Kossel - Lewis Approach to Chemical Bonding 🔴 Lewis Symbol 🔴 Chemistry for Class 11 in HINDI

In this Chemistry video in Hindi for class 11 we explained Kossel - Lewis approach to chemical bonding. They came to the conclusion, independently, that every atom has tendency to attain the electronic configuration of the nearest noble gas, which is very much stable in nature. And the atoms achieve this by forming chemical bond by transfer of electron (in case of electrovalent bond) or by sharing electrons (in case of covalent bond). Gilbert Newton Lewis postulated that atoms achieve the stable octet when they are linked by chemical bond. Basically Lewis explained the formation of covalent bond and Walther Kossel explained electrovalent bond.

Lewis pictured the atom in terms of a positively charged ‘Kernel’ (the nucleus plus the inner electrons) and the outer shell that could accommodate a maximum of eight electrons. He, further assumed that these eight electrons occupy the corners of a cube which surround the ‘Kernel’. Thus the single outer shell electron of sodium would occupy one corner of the cube, while in the case of a noble gas all the eight corners would be occupied. This octet of electrons, represents a particularly stable electronic arrangement. In the case of sodium and chlorine, this can happen by the transfer of an electron from sodium to chlorine thereby
giving the Na+ and Cl– ions. In the case of other molecules like Cl2, H2, F2, etc., the bond is formed by the sharing of a pair of electrons between the atoms. In the process each atom attains a stable outer octet of electrons.

Lewis Symbols: In the formation of a molecule, only the outer shell electrons take part in chemical combination and they are known as valence electrons. The inner shell electrons are well protected and are generally not involved in the combination process. Lewis introduced simple notations to represent valence electrons in an atom. These notations are called Lewis symbols.

Kossel, in relation to chemical bonding, drew attention to the following facts:
• In the periodic table, the highly electronegative halogens and the highly electropositive alkali metals are separated by the noble gases;
• The formation of a negative ion from a halogen atom and a positive ion from an alkali metal atom is associated with the gain and loss of an electron by the respective atoms;
• The negative and positive ions thus formed attain stable noble gas electronic configurations. The noble gases (with the exception of helium which has a duplet
of electrons) have a particularly stable outer shell configuration of eight (octet) electrons, ns2np6.
• The negative and positive ions are stabilized by electrostatic attraction.

The bond formed, as a result of the electrostatic attraction between the positive and negative ions was termed as the electrovalent bond. The electrovalence is thus equal to the number of unit charge(s) on the ion.

Class 11
Chemistry
Chapter 4 : Chemical Bonding and Molecular Structure

Click here for the full Playlist of this Chapter :
https://www.youtube.com/watch?v=0m-1NVUiT9s&list=PLW0F47OesfFMjYr4uG4qcb1dp9nuaZ9OL

Видео 🔴 Kossel - Lewis Approach to Chemical Bonding 🔴 Lewis Symbol 🔴 Chemistry for Class 11 in HINDI канала EduPoint