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ScienceQuest

Dichlorine monoxide (Cl₂O) Lewis structure

20 valence electrons, bent

O Cl Cl
Cl₂O as the Lewis Structure Generator draws it: lone pairs as dots.

Build Cl₂O step by step in the Lewis Structure Generator

What is the Lewis structure of Cl₂O?

Dichlorine monoxide, Cl₂O, has 20 valence electrons. Oxygen is the central atom, joined by two O−Cl single bonds. It carries two lone pairs on the central O and three on each Cl. Every formal charge is zero. O is AX₂E₂: bent, with an ideal bond angle of 109.5°, and the molecule is polar.

Valence electrons in Cl₂O

Element Group Valence electrons Atoms Electrons
Chlorine 17 7 2 14
Oxygen 16 6 1 6
Total 20

In one line: 2 × 7 + 6 = 20. Each atom brings the valence electrons its group gives it.

How to draw the Cl₂O Lewis structure

  1. Count the valence electrons. Valence electrons: each Cl 7 and O 6. 2 × 7 + 6 = 20.
  2. Choose the central atom. Cl is less electronegative, χ 3.16 against 3.44 for O, but Cl in the middle would need a Cl−Cl bond and 10 electrons round Cl, and electronegative atoms of one element avoid bonding to each other when they can. With O in the middle every atom has an octet and no formal charge.
  3. Join the atoms with single bonds. Two single bonds use 4 electrons, leaving 20 − 4 = 16.
  4. Complete the outer atoms. Each outer atom takes enough lone pairs to reach eight: 2 Cl × 6 = 12, leaving 16 − 12 = 4.
  5. Put the rest on the central atom. The 4 left go on the central atom as two lone pairs on O, and O now has 8 electrons round it.
  6. Make multiple bonds where needed. Every atom already has an octet, so no lone pair needs to become a bond.

Lone pairs and formal charges in Cl₂O

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
O (central) 1 two single bonds 2 8 6 − 4 − 2 = 0
Cl 2 one single bond 3 8 7 − 6 − 1 = 0

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.

Shape and polarity of Cl₂O

Central atom O
VSEPR class AX₂E₂
Electron geometry tetrahedral
Molecular geometry bent
Ideal bond angle 109.5°
Polarity, an estimate polar

The bent shape leaves the bond dipoles unbalanced.

O has two σ bonds and two lone pairs, four electron domains in all, so its electron geometry is tetrahedral. Counting only the bonded atoms, the molecular geometry is bent.

The VSEPR Molecular Geometry viewer turns the AX₂E₂ shape in 3D, lone pairs included.

Work with Cl₂O