Lewis Theory of Chemical Bonding

G.N. Lewis, a famous American chemist, introduced the concept of Lewis Symbols to represent the valence electron in an atom. 

Lewis and Kossel’s theory has studied the electronic configuration of noble gases. It found that the inertness of the noble gases is because of their complete octet or duplet in the Helium, which seems to have two electrons in its last shell. 

It offers generalisation, which means the atoms concerning the different elements seem to combine to complete their duplets or octet and avail the stable electronic configuration. 

This article will learn about the importance of the Kossel Lewis theory in chemical bond formation.

Importance of  Lewis Symbols

The number of dots surrounding the symbol will show the number of available valence electrons, which helps calculate the standard or group valence of the particular element.

According to the Kossel-Lewis approach, the atom related to different elements took active participation in combination to complete their octet (8 electrons in the outermost valence shell) or duplet (2 valence electrons in the outer valence shell) for attaining the nearest noble gas configuration. This complete process is known as Octet Rule.

Postulates of Lewis Theory

Lewis has discussed several facts about chemical bonding, and the important postulates comprise the following:

1. The highly electronegative halogens and highly electropositive alkali metals, seem to be segregated by the noble gases available under the periodic table.
2. The creation of the negative ion from halogen and positive ions from the alkali metals are related to electron gain and loss.
3. The positive ions and negative ions make the stable electronic configuration of noble gas configuration.
4. Each noble gas of the periodic table has the stable electronic configuration of the octet, excluding Helium which comprises duplet configuration.

Lewis Theory of Chemical Bonding Example

Considering the formation of NaCl, Na loses an electron, which chlorine (Cl) gains. By losing an electron, Na will achieve the stable configuration of Neon. On the other hand, Cl will attain the stable configuration of Argon by gaining an electron.

Importance of Lewis Postulations

Lewis’s postulates helped in:

1. Acknowledging and systemising ionic compounds
2. Creating the foundation for the latest ion-formation concepts with electron transfer

Lewis also understood that various compounds don’t fit into the concepts or categories mentioned. Lewis has provided the symbols to show the valence electron available around an atom; however, his partner Kossel introduced the postulate that explained why elements get combined with each to reach the stable electronic configuration.

Electronic Theory of Chemical Bonding:

Per this theory, which was proposed independently by Kossel & Lewis, a chemical bond is formed between atoms to get the nearest inert gas configuration. The element can achieve this configuration by either losing electrons or gaining electrons or by sharing electrons.

We can understand the structure and behaviour of atoms and molecules by using the theory of chemical bonding. This theory is an electronic theory, which means that it tries to explain chemical bonding in terms of the motions of the electrons within the atoms and molecules. 

The theory of chemical bonding makes predictions about how molecular structures and material properties are related to the arrangement of the electrons within them. 

The theory of chemical bonding has been a remarkably successful scientific theory. It has enabled us to make a wide range of predictions about the world and develop technologies such as drugs, plastics, and solar cells.

Ionic Bond:

An ionic bond is created by the overall transference of the particular number of electrons from one atom to another atom to ensure that they will achieve a stable electronic configuration. The elements of groups 1 and 2 combined with halogen, sulphur, and oxygen usually create ionic bonds. Some conditions necessary for forming the ionic bond are listed below.

1. Atoms forming the Cations i.e., positive ions, need lower ionisation energy, low electron affinity, low electronegativity, and high lattice energy.
2. Atoms forming Anions, i.e., negative ions, need to have high electron affinity, high electronegativity, high ionisation energy, and lattice energy.

Covalent Bond

The covalent bond forms when the atoms of the same or different elements will mutually combine by sharing the electrons. Therefore, we can say that a covalent bond forms by the mutual sharing of the electrons, like the formation of O2 molecules.

Conclusion

We have explained the Lewis and Kossel theory toward chemical bonding and its importance in forming ionic and electrovalent bonds. The Lewis- Kossel approach has great significance in forming chemical bonds. 

Chemical Bonds are what hold atoms together. Atoms always form these bonds with valence electrons of opposite spin. 

This aspect allows a bond formation only if both valence electrons are in the same quantum state. The two valence electrons in the bond are in different quantum states and have lower energy, and this bond is not stable.