Lewis Structure Generator
Reviewed carboxylate guide

CH₃COO⁻ Lewis Structure: Acetate Ion

Acetate is CH₃–COO⁻. The two oxygen atoms are equivalent in the resonance hybrid even though one contributor is drawn with C=O and the other with C–O⁻.

Reviewed July 16, 2026 · Organic Lewis model

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Quick answer

Electron count

2 C contribute 8, 3 H contribute 3, 2 O contribute 12 and the charge adds 1: 24 electrons.

Connectivity

The skeleton is H₃C–C–O₂. Both oxygens attach to the carbonyl carbon.

Resonance

Two equivalent contributors exchange the C=O bond and − charge.

Drawing steps

  1. Build the carbon skeleton CH₃–C.
  2. Attach both oxygen atoms to the second carbon.
  3. Complete the methyl carbon with three C–H bonds.
  4. Draw one C=O and one C–O⁻ while preserving 24 electrons.
  5. Draw the second contributor by swapping the double bond and negative charge.

What resonance means here

The real carboxylate ion is not rapidly switching between one short and one long C–O bond. The π electrons and negative charge are delocalized, making the two C–O bonds equivalent in the resonance hybrid.

Common mistake: moving the CH₃ group or oxygen atoms. Resonance changes electrons only; the atom skeleton stays fixed.