Lewis Structure

SO2 Lewis Structure

Sulfur dioxide

A common classroom drawing for SO2 has sulfur in the center with two S=O bonds and one lone pair on sulfur.

Use the diagram and steps below to check the sulfur dioxide Lewis structure, SO2 Lewis dot structure, valence electrons, formal charges, and molecular shape.

SO2 is often taught with resonance. Some courses draw one S=O and one S-O bond with formal charges; others use two S=O bonds for a zero-formal-charge structure.

SO2

Sulfur dioxide

18 e-
S O O
Valence electrons18
Central atomS
GeometryBent
Bond angleAbout 120 deg
PolarityPolar
Electron geometryTrigonal planar

VSEPR Geometry

Molecular geometry Bent
Electron geometry Trigonal planar
Bond angle About 120 deg
Polarity Polar
Valence electrons 18
Bonding / lone pairs 2 / 1
Central atom S
Electron regions 3

How to Draw SO2: Step-by-Step

1

Parse the molecular formula

SO2 -> S, O, O

The molecule contains one sulfur atom and two oxygen atoms.

2

Count total valence electrons

6 + 6 + 6 = 18

Sulfur contributes 6 electrons. Two oxygens contribute 12.

3

Choose the central atom

Central atom: S

Sulfur is placed in the center and both oxygens are terminal.

4

Draw the common form

O=S=O

The shown classroom form uses two S=O double bonds.

5

Place lone pairs

One lone pair on S; two on each O

The lone pair on sulfur makes the molecular shape bent.

6

Final answer

The shown SO2 Lewis structure has two S=O double bonds, one lone pair on sulfur, and two lone pairs on each oxygen.

Formal Charges

AtomFormal charge
S0 in the shown form
O0 in the shown form

Common Mistakes

  • SO2 is bent because sulfur has a lone pair.
  • Check which resonance convention your class expects.

FAQ

What is the Lewis structure for SO2?

The shown SO2 Lewis structure has two S=O double bonds, one lone pair on sulfur, and two lone pairs on each oxygen.

What is the Lewis dot structure for SO2?

The Lewis dot structure for SO2 is the electron-dot drawing shown above. The shown SO2 Lewis structure has two S=O double bonds, one lone pair on sulfur, and two lone pairs on each oxygen.

How many valence electrons does SO2 have?

SO2 has 18 total valence electrons in this Lewis structure.

What is the molecular geometry of SO2?

SO2 has bent molecular geometry and trigonal planar electron geometry.

Is SO2 polar or nonpolar?

SO2 is polar in the Lewis structure shown here. Its molecular geometry is Bent.

References

Method notes are aligned with standard Lewis structure steps: count valence electrons, draw a skeleton, distribute electrons, form multiple bonds when needed, and check formal charges and resonance.

OpenStax Chemistry 2e: Lewis Symbols and Structures and Formal Charges and Resonance.