Question

In the following structure of $CO_3^{2-}$ formal charges on carbon atom, double bonded oxygen atom and single bonded oxygen atom are respectively

• A. $- 1 ,0 ,0$
• B. $1, -2 ,0$
• C. $0 ,0 ,-1$
• D. $0, -1, 0$

Answer 1

Answer: (C)

Lewis structure of $CO_3^{2-}$ ion is

Formal charge = [valence electrons - lone pair electrons
$-\frac{1}{2}$ bonding electrons]
Formal charge on carbon atom$= 4 - \frac{1}{2} \times 8 = 0$
Formal charge on double bonded $O$ atom $= 6 - 4 - \frac{1}{2} \times 4$
$=0$
Formal charge on single bonded $O$ atom
$= 6 -6 - \frac{1}{2} \times 2$
$ = -1$