Question

↵why does sulphur hv 5 free electrons instead of 6:


Q5. What is the formal charge on the sulphur atoms in a SO₄^2- ion ?​

A. 0
B. -1
C. +2
D. +3

Answer 1

No, the valence electrons in Sulphur is 6. Thus, we calculate formal charge as follows:

Formal Charge = Number of valence electrons - Number of non bonding electrons - (1/2) Number of bonding electrons


For S:
Formal Charge = 6-0-(12/2) = 6-6 = 0

For O:
Formal Charge = 6-2-(4/2) = 2

Thus Formal charge = -2.