How do you calculate the formal charge of O3?

Question

Ellie Adams · Accepted Answer

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

There are 18 valence electrons to divide among the three oxygen atoms (a total of 24 electrons; 6 are inner core) based on basic VSEPR calculations. Typically, a Lewis structure of #O=stackrel(ddot)O^(+)-O^(-)#, would be depicted. Going from left #O# to right #O# 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 #0#, #+1#, and #-1#, respectively. Of course, I can draw the other resonance structure, but the Lewis structure has the same electronic formulation. The #/_O-O-O# #~=117^@#; this is slightly LESS than the normal #sp_2# bond angle of #120^@#, due to disproportionate influence of the oxygen lone pair, which tends to compress #/_O-O-O#. This molecule is bent because the central oxygen contains three regions of electron density.

Emilia Alvarez · Answer

undefined To calculate the formal charge of O3 (ozone), you use the formula:

Formal Charge = Valence Electrons - (Number of lone pair electrons + 0.5 * Number of bonding electrons)

For O3, oxygen has 6 valence electrons. In ozone, there are 3 oxygen atoms, each forming a double bond with one another. Each oxygen atom shares one lone pair of electrons.

Formal Charge = 6 - (6 lone pair electrons + 0.5 * 12 bonding electrons)
             = 6 - (6 + 6)
             = 6 - 12
             = -6

So, each oxygen atom in O3 has a formal charge of -1.