Question

All the pcl bonds in pcl5 molecules are not equivalent why ?

Answer 1

PCl5 has a trigonal bipyramidal structure due to the dsp3 hybridization. Due to this trigonal bipyramidal structure, the 2wo Cl-atoms of PCl5 molecule are stretched at the axis and become little longer and so called as axial bonds, while the rest three Cl-atoms lie on the equator and called as equatorial bonds.

We know, that the axial bonds are more stretched and longer than equatorial bonds so, the three equatorial Cl-atoms become equivalent and the two axial Cl-atom become equivalent while, both the groups are not identical which makes the difference in bonding of PCl5 molecule.

Answer 2

Answer:

in PCl3 hybridization of phosphorus is sp3 where is in PCl5 it is sp3d.

Also according to vsepr PCl3 has trigonal pyramidal shape where as PCl5 has trigonal bipyramidal shape. In trigonal bipyramidal the longitudinal and equatorial bond lengths differ