Thiosulfate Ion overview
The stored Lewis connectivity is [S—S(=O)₂—O]²⁻. One terminal sulfur replaces an oxygen in a sulfate-like framework; formal-charge placement and resonance require careful bookkeeping.
How to draw S₂O₃²⁻
- Count 32 valence electrons. Include charge adjustments before drawing.
- Use the reviewed connectivity [S—S(=O)₂—O]²⁻. Do not infer a different isomer from the formula alone.
- Place the required single, double or multiple bonds. Keep a running electron total.
- Complete terminal valence shells and add lone pairs or formal charges. One terminal sulfur replaces an oxygen in a sulfate-like framework; formal-charge placement and resonance require careful bookkeeping.
- Verify the total electron count and geometry. The reviewed geometry is Approximately tetrahedral around the central sulfur.
Why this example matters
One terminal sulfur replaces an oxygen in a sulfate-like framework; formal-charge placement and resonance require careful bookkeeping.
Scope and model limits
The displayed contributor is an educational Lewis model. S–S and S–O bonding is delocalized and not fully described by one expanded-octet sketch.
Common mistakes
- Using a sulfate formula
- Omitting the S–S bond
- Forgetting the overall 2− charge
Related reviewed guides
Last reviewed: 2026-07-16. Educational reference only; verify graded work with course materials.