Explain why PCl5 is trigonal bipyramidal whereas IF5 is square pyramidal.


PCl5-The ground state and the excited state outer electronic configurations of phosphorus (Z=15) are represented below
In PCl5, P is sp3d hybridised, therefore, its shape is trigonal bipyramidal.
IF5-The ground state and the excited state outer electronic configurations of iodine (Z=53) are represented below.
In IF5, I is sp3d2 hybridised, therefore, shape of IF5 is square pyramidal.