In phosphorous oxychloride (POCl₃), phosphorous shares single covalent bonds with all three chlorine (Cl) atoms and a double covalent bond with the oxygen (O) atom. Its Lewis structure is shown below.

Let us calculate the formal charge of POCl₃ by calculating the formal charges on P, O, and Cl.

Phosphorous

V = 5, N = 0, B = 8

Therefore,

q_f = 5 – 0 – 10/2 = 0

The formal charge on P in POCl₃ is zero.

Oxygen

V = 6, N = 4, B = 4

Therefore,

q_f = 6 – 4 – 4/2 = 0

The formal charge on O in POCl₃ is zero.

Chlorine 1, Chlorine 2, and Chlorine 3

V = 7, N = 6, B = 2

Therefore,

q_f = 7 – 6 – 2/2 = 0

The formal charge on Cl in POCl₃ is zero.

The net formal charge is: 0 + 0 + 3 x 0 = 0

The formal charge of POCl₃ is zero. The structure shown above is the most stable.