Question

What is the covalency of oxygen and nitrogen molecules?
A. $0,0$.
B. $1,2$.
C. $2,3$.
D. $3,3$.

Answer 1

Hint: We know, Covalency is defined as the number of electrons present in the outermost shell which is shared by an atom in a compound. The atomic number of oxygen and nitrogen is $8$ and $7$ respectively.

Complete step by step answer: Now we see the chemical activity of a substance related to the valence electrons.
The chemical activity of a compound or an atom depends on the number of outermost electrons. If the outermost shells are filled then the atom is inert. If the outermost shell is not filled then to fill the outermost shell, it accepts or donates electrons between other atoms.
We know that the valency of an atom is the number of electrons present in the outermost shell. If the electrons are shared between covalent compounds then it is termed as covalency.
For Example, The number of valence electrons in carbon is four and it needs four more electrons to have filled outermost electrons and hydrogen has one electron in its valence shell so carbon shares electrons with four hydrogen atoms. Thus the covalency of carbon is four.
The number of valence electrons in oxygen is six and it needs two electrons to have a filled configuration. Thus, the covalency of oxygen is two as it forms a double bond and the number of valence electrons in nitrogen is five and it needs three electrons to have a filled configuration that of nitrogen is three as it forms a triple bond.
So, the correct answer is “Option C”.

Note: We must remember that the covalency and electrovalency are different from each other. If the donation or acceptance of electrons occurs in an ionic compound then it is called electrovalency.