In POCl₃, Phosphorous will form 5 bonds. The bonds formed are as,
* Two Bonds (Double Bond) with Oxygen atom
* Three Bonds (Single Bond each) with three Chlorine atoms.
Formal charge:
Formal Charge is calculated using following formula,
Formal Charge = [# of Valence e⁻s] - [e⁻s in lone pairs + 1/2 e⁻s in bonding e⁻s]
Valence electrons of P = 5
e⁻s in lone pair = 0
e⁻s in Bonding = 10
So,
Formal Charge = [5]-[0+10/2]
Formal Charge = [5]-[5]
Formal Charge = 0