What Is the Molecular Geometry of SO₃²⁻?
📚 Confused about how to draw SO₃²⁻ or determine its shape? You’re not alone. Sulfite ion problems show up frequently in General Chemistry and on ALEKS assignments — and they can be trickier than they look.
This guide will walk you through the full breakdown: Lewis structure, electron geometry, molecular geometry, hybridization, and polarity — all in one place.
🔬 Step 1: Lewis Structure of SO₃²⁻
- Total valence electrons: 26 (6 from S + 6×3 from O + 2 from the -2 charge)
- Central atom: Sulfur (S)
- Arrangement: Three S–O single bonds and one lone pair on the sulfur
- Resonance: The negative charge is delocalized over the three oxygen atoms via resonance
✅ This arrangement satisfies the octet rule for all atoms and allows resonance stabilization.
📐 Step 2: Electron Geometry
With three bonding domains and one lone pair around the central sulfur atom, the electron geometry is tetrahedral.
📐 Step 3: Molecular Geometry
Because one of the four electron regions is a lone pair, the actual molecular geometry becomes trigonal pyramidal.
Electron Geometry = Tetrahedral
Molecular Geometry = Trigonal Pyramidal
Approximate Bond Angles = ~107.5°
🧪 Step 4: Hybridization
The central sulfur atom uses sp³ hybrid orbitals to accommodate the three sigma bonds and one lone pair.
🧲 Step 5: Polarity of SO₃²⁻
Because the molecular geometry is asymmetrical and the oxygen atoms are more electronegative, the sulfite ion is polar.
🎯 Real-World Examples of SO₃²⁻ Questions
Here are common ways SO₃²⁻ appears in chemistry courses:
- “Draw the Lewis structure and determine the molecular geometry of SO₃²⁻.”
- “Is SO₃²⁻ polar or nonpolar?”
- “What is the hybridization of the central atom in SO₃²⁻?”
💡 Pro Tip: Know Your Geometry Names
Don’t confuse electron geometry with molecular geometry:
- Electron geometry considers all electron domains (bonds and lone pairs)
- Molecular geometry only considers bonded atoms
🧠 How Finish My Math Class Can Help
If SO₃²⁻ diagrams or VSEPR theory are slowing you down in ALEKS Chemistry, MasteringChemistry, or Cengage MindTap, we can help with:
- Assignments & labs on molecular geometry
- Lewis structure drawing tasks
- VSEPR and hybridization questions
We’ll do the hard parts — and guarantee a high grade or your money back.
🔗 Related Pages
- Do My Chemistry Homework
- Do My ALEKS Chemistry Labs
- ALEKS Chemistry Answers
- Pass ALEKS General Chemistry Fast
- Macmillan Achieve Chemistry Help
- How to Cheat on ALEKS
- See All Services
❓ FAQ: SO₃²⁻ Molecular Geometry
Q: Is SO₃²⁻ trigonal planar?
No. Trigonal planar geometry occurs when there are three bonding groups and no lone pairs. SO₃²⁻ has one lone pair on sulfur, making it trigonal pyramidal.
Q: What is the bond angle in SO₃²⁻?
Approximately 107.5°, due to the repulsion caused by the lone pair on the central sulfur atom.
Q: What type of hybridization is used in SO₃²⁻?
sp³ hybridization, due to the four electron domains (three bonds + one lone pair).
Q: Is SO₃²⁻ polar or nonpolar?
Polar. The shape is asymmetrical, and the oxygen atoms pull electron density unevenly.
Q: How many resonance structures does SO₃²⁻ have?
Three equivalent resonance structures, where the negative charge is delocalized among the oxygen atoms.
Q: Can you do my SO₃²⁻ assignment for me?
Yes! Whether it’s an ALEKS module, MasteringChemistry question, or full chemistry class, our experts are ready. Submit your assignment.
🎓 Bottom Line
The molecular geometry of SO₃²⁻ is trigonal pyramidal, shaped by three bonding pairs and one lone pair on the sulfur. If this topic is confusing, you’re not alone — it’s one of the most commonly misunderstood ions in General Chemistry.
Whether you’re stuck on molecular geometry, balancing redox reactions, or naming organic compounds, our Do My Chemistry Homework service can handle it all — with guaranteed high grades or your money back.
Need help with chemistry assignments? Contact the Finish My Math Class team today and let us do the hard part.