Question

Explain the difference between the valence electrons and the covalency of an element.

Answer 1

Valency is the number of free electron/electrons in the outermost shell of an element. The greatest valency could be 4.

When the valency of an element is 4 it can neither lose nor accept 4 electrons to form an ionic bond , because it would be difficult for nucleus with six protons to hold on to ten electrons, that is four extra electrons.(take in case of carbon with valency 4).

Also it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to just two electrons. Carbon overcomes this problem this problem by sharing its valence electrons with atoms of other elements.not just carbon but many other elements form molecule by sharing the outer shell electron in this manner such bonds which are formed by sharing of an electron pair between two atoms are known as covalent bond.