Question

$BC{l}_3$ molecule is planar while $NC{l}_3$ is pyramidal because:

• A. $BC{l}_3$ does not have a lone pair on $B$ but $NC{l}_3$ has one lone pair on $N$.
• B. $B-Cl$ bond is more polar than $N-Cl$ bond.
• C. $N$ atom is smaller than $B$.
• D. $N-Cl$ bond is more covalent than $B-Cl$ bond.

Answer 1

Answer: (A)

$BC{l}_3$ does not have a lone pair on $B$ but $NC{l}_3$ has one lone pair on $N$.

$BC{l}_3$ molecule is planar while $NC{l}_3$ is pyramidal because $BC{l}_3$ does not have lone pair on B but $NC{l}_3$ has one lone pair on N.
The $B$ atom in $BC{l}_3$ is $s{p}^2$ hybridised which results in trigonal planar geometry.
The $N$ atom in $NC{l}_3$ is $s{p}^3$ hybridised which results in tetrahedral electron pair geometry and pyramidal molecular geometry.