Question

$PC{l}_5$ has a shape of trigonal bipyramid whereas $I{F}_5$ has the shape of a square pyramid. It is due to:

• A. presence of unshared electron pair on $I$ which is oriented so as to minimize repulsion while $P$ in $PC{l}_5$ has no unshared pair
• B. octet of $P$ is complete while that of $I$ is incomplete
• C. $P$ and $I$ are of different groups
• D. $F$ and $Cl$ have different extent of repulsion

Answer 1

The correct option is A presence of unshared electron pair on $I$ which is oriented so as to minimize repulsion while $P$ in $PC{l}_5$ has no unshared pair

${PCl}_5$ = $\begin{array}{ccccc}& & Cl& & Cl\\ & & |& /& \\ Cl& -& P& -& Cl\\ & & |& & \\ & & Cl& & \end{array}$

There are no lone pairs, hence no repulsion.

Whereas in ${IF}_5$; Iodine has lone pair electrons. the geometry is thus the geometry is arranged in such a way, so, as to minimize the repulsion between the lone pair and bounded pair of electrons.

It has a Square pyramid geometry.