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Ozone (O₃) Lewis structure

18 valence electrons, bent

O O O + −
O₃ as the Lewis Structure Generator draws it: lone pairs as dots, nonzero formal charges circled.

Build O₃ step by step in the Lewis Structure Generator

What is the Lewis structure of O₃?

Ozone, O₃, has 18 valence electrons. Oxygen is the central atom, joined by one O=O double bond and one O−O single bond. Its formal charges are +1 on the central O and −1 on the single-bonded O. It has two equivalent resonance forms. O is AX₂E₁: bent, and the molecule is polar.

Valence electrons in O₃

Element Group Valence electrons Atoms Electrons
Oxygen 16 6 3 18
Total 18

In one line: 3 × 6 = 18. Each atom brings the valence electrons its group gives it.

How to draw the O₃ Lewis structure

  1. Count the valence electrons. Valence electrons: each O 6. 3 × 6 = 18.
  2. Choose the central atom. Every atom here is O, so one O goes in the middle and the others bond to it.
  3. Join the atoms with single bonds. Two single bonds use 4 electrons, leaving 18 − 4 = 14.
  4. Complete the outer atoms. Each outer atom takes enough lone pairs to reach eight: 2 O × 6 = 12, leaving 14 − 12 = 2.
  5. Put the rest on the central atom. The 2 left go on the central atom as one lone pair on O, and O now has 6 electrons round it.
  6. Make multiple bonds where needed. O has only 6 electrons, so one lone pair moves into the bonds, making an O=O bond, and O now has 8.

Lone pairs and formal charges in O₃

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
O (central) 1 one double bond and one single bond 1 8 6 − 2 − 3 = +1
O 1 one double bond 2 8 6 − 4 − 2 = 0
O 1 one single bond 3 8 6 − 6 − 1 = −1

V is the atom’s valence electrons, N its nonbonding electrons and B its bonding electrons. The formal charges add up to 0, the molecule’s overall charge.

Resonance structures of O₃

The two forms differ only in where the electrons sit, so the real molecule is one structure, their average, the resonance hybrid. Two O−O bonds each have an average order of 3/2. Two O atoms share a formal charge of −1 between them, −1/2 each.

O O O + −
Form 1
O O O + −
Form 2
O O O + −1/2 −1/2
Resonance hybrid, partial bonds dashed

Shape and polarity of O₃

Central atom O
VSEPR class AX₂E₁
Electron geometry trigonal planar
Molecular geometry bent
Ideal bond angle 120°
Polarity, an estimate polar

The bent shape leaves the bond dipoles unbalanced.

O has two σ bonds and one lone pair, three electron domains in all, so its electron geometry is trigonal planar. Counting only the bonded atoms, the molecular geometry is bent.

The VSEPR Molecular Geometry viewer turns the AX₂E₁ shape in 3D, lone pairs included.

Work with O₃