Lewis Structure Generator
Formic Acid · HCOOH

HCOOH Lewis Structure

The acid hydrogen is attached to oxygen, while the carbonyl oxygen forms a double bond to carbon.

Open HCOOH in the generatorSee drawing steps
HCOOH
H—C(=O)—O—H
Reviewed stored connectivity; detailed electron placement is explained below
Total valence electrons18
Reviewed connectivityH—C(=O)—O—H
GeometryTrigonal planar at the carbonyl carbon
Support levelReviewed guide

Formic Acid overview

The stored Lewis connectivity is H—C(=O)—O—H. The acid hydrogen is attached to oxygen, while the carbonyl oxygen forms a double bond to carbon.

How to draw HCOOH

  1. Count 18 valence electrons. Include charge adjustments before drawing.
  2. Use the reviewed connectivity H—C(=O)—O—H. Do not infer a different isomer from the formula alone.
  3. Place the required single, double or multiple bonds. Keep a running electron total.
  4. Complete terminal valence shells and add lone pairs or formal charges. The acid hydrogen is attached to oxygen, while the carbonyl oxygen forms a double bond to carbon.
  5. Verify the total electron count and geometry. The reviewed geometry is Trigonal planar at the carbonyl carbon.

Why this example matters

The acid hydrogen is attached to oxygen, while the carbonyl oxygen forms a double bond to carbon.

Scope and model limits

The neutral molecular Lewis structure is shown; acid dissociation produces formate and hydronium in water.

Common mistakes

  • Attaching both hydrogens to carbon
  • Drawing two equivalent C–O bonds in the neutral acid
  • Omitting oxygen lone pairs

Last reviewed: 2026-07-16. Educational reference only; verify graded work with course materials.