How do you calculate the formal charge of O3?

1 Answer
Nov 7, 2015

The formal charge of the ozone molecule is zero. Its Lewis structures do present charge separation.

Explanation:

With simple VSEPR considerations, there are 18 valence electrons to distribute around the 3 oxygen atoms (24 electrons in total; 6 are inner core).

Typically, a Lewis structure of O=stackrel(ddot)O^(+)-O^(-)O=..O+O, would be depicted. Going from left OO to right OO and including the 2 inner core electrons on each atom, there are 8, 7, and 9 electrons around each oxygen centre, resulting in formal charges of 00, +1+1, and -11, respectively. Of course, I can draw the other resonance structure, but the Lewis structure has the same electronic formulation. The /_O-O-OOOO ~=117^@117; this is slightly LESS than the normal sp_2sp2 bond angle of 120^@120, due to disproportionate influence of the oxygen lone pair, which tends to compress /_O-O-OOOO.

Since the central oxygen has 3 regions of electron density, this molecule is bent.