Question

Electronic theory of valency was presented by:
(A) Pauling
(B) Werner
(C) Kossel and Lewis
(D) Heitler and London

Answer 1

Hint Electronic theory of valency states that electrons themselves are responsible for chemical combination. It is the tendency of electrons to occupy inert electronic configuration of the nearest inert gas.

Complete step by step answer:
- The Electronic theory of valency states that every element has a tendency to attain electronic configuration of the nearest inert gas, as it is the most stable configuration called stable octet, which consists of 8 electrons or a duplet consisting 2 electrons and the number of electrons it accepts or donates is its valency.
- According to electronic configuration, the stable number is required to make the stability.
- For example, Boron has electronic configuration 2,3. So, in this case, it would like to accept 3 electrons to attain octet. And so, its valency would be +3. Since, oxygen has atomic no. 8 with electronic configuration 2,6 and needs to gain 2 electrons to become stable, so valency 2.
- The electronic theory of valency was independently originated by Gilbert N. Lewis and Walther Kossel in 1916. This theory was later applied by Langmuir in 1919.
- The stable configuration is attained to form steadiness. It is achieved by either transference of electrons, sharing of electrons or donation of lone pairs of electrons.

So, the answer to the question is (C) Kossel and Lewis.

Note: The electrons present in the outermost orbit of each and every element are called valence electrons and that shell is called valence shell. The valency of every element is explained on the basis of the number of electrons present in it.