Lewis Structure Generator
Reviewed transition-metal oxyanion guide

CrO₄²⁻ Lewis Structure: Chromate Ion

A common Lewis bookkeeping contributor uses two Cr=O bonds and two Cr–O⁻ bonds. Choosing which two oxygens are single bonded gives six equivalent placements.

Reviewed July 16, 2026 · Educational bookkeeping model

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Quick answer

Electron count

Cr contributes 6, four O contribute 24 and the 2− charge adds 2: 32 electrons.

Geometry

Four oxygen positions around chromium give a tetrahedral arrangement.

Contributors

Two single-bonded O⁻ positions can be selected in 6 equivalent ways.

Drawing method

  1. Connect chromium to four oxygen atoms.
  2. Complete oxygen octets and keep the 32-electron total.
  3. In the displayed minimized-charge form, use two Cr=O and two Cr–O⁻ bonds.
  4. Bracket the structure and label the 2− overall charge.
  5. Recognize six equivalent electron-placement contributors.

Why this is a model

Chromium is a transition metal, so a simple dot-and-line drawing cannot fully describe metal–oxygen bonding. The Lewis representation remains useful for formal-charge exercises and comparing overall electron counts.

Common mistake: treating the six contributors as six different atom arrangements. The four oxygen positions remain fixed; only the Lewis electron placement changes.