Question

In case of nitrogen, $NC{l}_3$ is possible but not $NC{l}_5$, whereas in case of phosphorous, $PC{l}_3$ as well as $PC{l}_5$ are possible. It is due to:

• A. Availability of vacant d-orbitals in $P$ but not in $N$
• B. Lower electronegetivity of $P$ than $N$
• C. Lower tendency of hydrogen bond formation in $P$ than $N$
• D. Occurance of $P$ is solid whereas $N$ is in gaseous state at room temperature

Answer 1

The correct option is A Availability of vacant d-orbitals in $P$ but not in $N$

(a) Number of covalent bonds that can be formed is the number of unpaired electrons in the outermost orbit of central atom in ground or excited state.


$N$ can form $3$ bonds in ground state.


Phosphorous can form $3$ bonds in ground state and $5$ bonds in excited state because it has vacant $3d$-orbitals in the outermost orbit.
So, $PC{l}_5$ is possible but not $NC{l}_5$.