Question

The theory developed by Kossel and Lewis are called:
(A) Valence bond theory
(B) Electronic theory of valence
(C) Ligand field theory
(D) None of the above

Answer 1

Hint: Any system with more energy is less stable. So every system tends to attain stability by losing energy. The same is followed by an atom according to the octet rule.

Complete step by step answer:
Kossel and Lewis developed the electronic theory of valence to explain the formation of chemical bonds between the two atoms. According to this theory, every atom tries to attain octet configuration (presence of eight electrons) in its valence shell by losing or gaining or by sharing of electrons. This is known as the "Octet Rule".
The electrostatic forces of attraction that hold two oppositely charged ions together are known as electrovalent bonds.
Atoms attain stability by forming bonds. The process of bond formation is associated with the lowering of its energy.
It is only the valence electrons that participate in chemical bonding, but not inner electrons.
To understand the concept of valence electrons Lewis introduced this concept of representing valence electrons with dots and these are named the Lewis symbols.
Are Lewis symbols important? Yes they are!
They provide the number of outermost electrons around the atom. With the help of the number of outermost or valence electrons we can easily calculate the valency of the atom.
Kossel claims that to gain stability halogens gain electrons while alkali metals loose electrons. During these processes they acquire the octet configuration.

The correct option is (B) Electronic theory of valence.

Note: The electron bond formation is explicitly defined in two ways. They are ionic (which includes complete transfer of electrons) and covalent (which includes sharing of electrons) bonding.