Chemistry - GOC Question with Solution | TestHub

Formal charges help in selection of the lowest energy structure from a number of possible Lewis structures for a given species. Generally the lowest energy structure is the one with the smallest formal charges on the atoms. Formal charge on an atom $=$ total no. of valence electrons-non-bonding electrons $-\frac{1}{2}\times$ bonding electrons. For Lewis structure of ${\mathrm{SO}}_3$
Formal charge on $\mathrm{S}$ atom $$=6-0-\frac{1}{2}\times 12=0$$ Formal charge on three $\mathrm{O}$ atoms $$=6-4-\frac{1}{2}\times 4=0$$