Question

How does the structure of $PCl_{5}$ is responsible for its high reactivity?

Answer 1

In $PCl_{5}$ consists of different types of P-Cl bonds:

i)        Axial bonds (two chlorine atoms bonds with P axially)  

ii)        Equatorial bonds (three chlorine atoms having bond length equi-distant from P)  

iii)        It is known that axial bonds are longer than equatorial bonds.

iv)        Due to unequal bond lengths between axial and equatorial bonds, $PCl_{5}$ is unstable and highly reactive.

v)        Structure of $PCl_{5}$ is as follows,