Question

What is the formal charge on 'S' and 'O' atoms in SO₂ molecule?

Answer 1

The resonance structure of SO₂ is actually as follows:
O=S-O^-

As in this structure the octet rule is followed,
the formal charge on
FC = V– N–B/2
Where V is the number of valence elctrons of the atom in the free atom; N is the number of non-bonding electrons on this atom in the molecule; and B is the total number of electrons shared in covalent bonds with other atoms in the molecule.

So for O (right side) = 6 – 6 – (2/2) = –1.
and for S = 6 – 2 – (6/2) = +1
Thus the molecule is electrically neutral.