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ScienceQuest

Hypochlorous acid (HOCl) Lewis structure

14 valence electrons, bent

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

Build HOCl step by step in the Lewis Structure Generator

What is the Lewis structure of HOCl?

Hypochlorous acid, HOCl, has 14 valence electrons. Oxygen is the central atom, joined by one O−H single bond and one O−Cl single bond. It carries two lone pairs on the central O and three on the 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 HOCl

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

In one line: 1 + 6 + 7 = 14. Each atom brings the valence electrons its group gives it.

How to draw the HOCl Lewis structure

  1. Count the valence electrons. Valence electrons: H 1, O 6 and Cl 7. 1 + 6 + 7 = 14.
  2. Choose the central atom. O goes in the middle: with any other atom there, no arrangement gives every atom an octet.
  3. Join the atoms with single bonds. Two single bonds use 4 electrons, leaving 14 − 4 = 10.
  4. Complete the outer atoms. The outer Cl takes 6 electrons as lone pairs to reach eight, leaving 10 − 6 = 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 HOCl

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
H 1 one single bond 0 2 1 − 0 − 1 = 0
Cl 1 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 HOCl

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

Bonds of different polarity do not cancel in this shape.

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 HOCl