Final answer:
In HCN, the nitrogen atom has no lone pairs of electrons as its five valence electrons are used up in bonding; three of them form a triple bond with carbon, and the remaining two form a single bond with hydrogen.
Step-by-step explanation:
The nitrogen atom in HCN is triple-bonded to carbon and has one bond with hydrogen. Nitrogen has 5 valence electrons, and after forming a triple bond with carbon (which accounts for 6 electrons, 3 pairs) and a single bond with hydrogen (which accounts for 2 electrons, 1 pair), one electron remains unpaired. However, since nitrogen tends to form stable compounds by completing its octet, it would typically use any unpaired electrons to form a bond rather than keeping them as a lone pair. In the case of HCN, after the bonding described, there are no lone pairs of electrons on the nitrogen atom, as all its valence electrons are involved in bonding.