Skip to content
ScienceQuest

Hydroxyl radical (OH) Lewis structure

7 valence electrons, linear

O H
OH as the Lewis Structure Generator draws it: lone pairs as dots, the odd electron ringed.

Build OH step by step in the Lewis Structure Generator

What is the Lewis structure of OH?

Hydroxyl radical, OH, has 7 valence electrons. Its two atoms are joined by one O−H single bond. It carries two lone pairs on the O. One electron is left unpaired, on the O. Every formal charge is zero. As two atoms it is linear, and the molecule is polar.

Valence electrons in OH

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

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

How to draw the OH Lewis structure

  1. Count the valence electrons. Valence electrons: O 6 and H 1. 6 + 1 = 7.
  2. Join the two atoms. With only two atoms there is no choice to make: they bond to each other.
  3. Join the atoms with single bonds. One single bond uses 2 electrons, leaving 7 − 2 = 5.
  4. Complete the outer atoms. Every outer atom is H, and its one bond already gives it the two electrons it holds. 5 remain.
  5. Put the rest on O. The 5 left go as two lone pairs on O and one unpaired electron, and O now has 7 electrons round it.
  6. Make multiple bonds where needed. O is left with 7 electrons, one of them unpaired. Every atom bonded to it is H, which has no lone pair to turn into a second bond, so O stays at 7.

Lone pairs and formal charges in OH

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
O 1 one single bond 2 and 1 unpaired electron 7 6 − 5 − 1 = 0
H 1 one single bond 0 2 1 − 0 − 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 OH

Central atom none, two atoms
Electron geometry linear
Molecular geometry linear
Ideal bond angle none, two atoms
Polarity, an estimate polar

The electronegativities differ by 1.24, so the shared electrons sit nearer O.

Notes on the OH Lewis structure

Work with OH