The nitrogen atom shows a maximum covalency of

Options

A. six
B. five
C. four
D. three

Answer

C

Explanation

Usually, the number of bonds formed by an atom (of representative element like N) that is bonded to less electronegative atoms (like H) will be equal to 8 minus its group number (old nomenclature) in the periodic table. Thus, N usually forms `8-5=3` covalent bonds.
The number of bonds is often the same as the number of unpaired valence electrons of each atom that are available for bonding. For example, the ground state electron configuration of nitrogen, which usually forms three bonds, is
`[He]2s^2 2p_x^1 2p_y^1 2p_z^1`
Nonmetals can form compounds in which they do not have the expected number of bonds. Nitric acid, `NHO_3`, is such a compound. In the Lewis structure of `HNO_3`, the N atoms has four bonds:

The N atom has five valence electrons

Three of the unpaired electrons are used to form three normal covalent bonds while the fourth bond is formed by N through its `2s^2` electron pair. Thus, the fourth bond is always a dative bond.