Question

The structure of $ICl_6^ -$ is:
A.Pentagonal bipyramid
B.Square pyramid
C.Trigonal bipyramid
D.Octahedral

Answer 1

Start by calculating the hybridization of the given molecule and then determining the geometry. The structure of the chemical may then be easily identified. Keep in mind that the compound's shape and structure do not have to be identical.

Complete answer:

Z	Hybridization	Geometry
2	$sp$	Linear
3	$s{p^2}$	Trigonal planar
4	$s{p^3}$	Tetrahedral
5	$s{p^3}d$	Trigonal bipyramidal
6	$s{p^3}{d^2}$	Octahedral
7	$s{p^3}{d^3}$	Pentagonal bipyramidal

We know that the hybridization of this molecule is $s{p^3}{d^3}$. Hence looking at the table above we notice that its structure is pentagonal pyramidal.

Hence the correct option is option A.

ADDITIONAL INFORMATION:
The shape of a molecule may be predicted using the valence shell electron pair repulsion (VSEPR) hypothesis by attempting to optimise the space between electron pairs (bond and lone pairs). While electron pair geometry considers the shape formed by both bonds and lone pairs around a central atom, molecular geometry solely considers the shape of the atoms surrounding the core atom and ignores the lone pairs.
The pentagonal bipyramid is 4-connected, which means that disconnecting the remaining vertices requires the removal of four vertices.

Note:
Another easy way would be by understanding that Because chlorine has a large size, due to steric crowding by 6 chlorine atoms, the lone pair does not participate in hybridization or, to put it another way, it occupies an orbital with 100% s character, leaving the other orbitals $s{p^3}{d^3}$, giving the molecules a perfect octahedral form.