Lewis Structure Generator
Reviewed carbonyl guide

CH₂O Lewis Structure: Formaldehyde

Formaldehyde is H₂C=O. Carbon forms two C–H single bonds and one C=O double bond, while oxygen carries two lone pairs.

Reviewed July 16, 2026 · Introductory organic structure

Generate CH₂OOrganic drawing guide

Quick answer

Electron count

C contributes 4, two H contribute 2 and O contributes 6: 12 electrons.

Bonding

Two C–H single bonds and one C=O double bond use 8 bonding electrons.

Geometry

Three electron domains around carbon produce trigonal-planar geometry near 120°.

Drawing steps

  1. Put carbon in the center, with two hydrogens and one oxygen terminal.
  2. Connect all atoms with single bonds.
  3. Complete the oxygen octet with lone pairs.
  4. Carbon is still short of an octet, so convert one oxygen lone pair into a C=O bond.
  5. Leave two lone pairs on oxygen and verify all formal charges are zero.

Why the double bond is required

With only single bonds, carbon would have six surrounding electrons after the available electrons are placed. The C=O double bond completes carbon's octet without changing the 12-electron total.

Common mistake: drawing an O–H bond. The molecular formula is compatible with the carbonyl connectivity H₂C=O; both hydrogens are bonded to carbon.