Is Sulfur Trioxide (SO₃) Polar or Nonpolar?
Is Sulfur Trioxide (SO₃) polar or nonpolar?
SO₃ has three polar S=O bonds (ΔEN = 0.86), but the trigonal planar geometry with 120° angles causes complete cancellation. No lone pair on sulfur to break the symmetry. Compare SO₃ (nonpolar) to SO₂ (polar) - one extra oxygen removes the lone pair.
| Formula | SO₃ |
| Polarity | Nonpolar |
| Molecular Geometry | Trigonal Planar |
| S=O Bond | ΔEN = 0.86 (polar) |
| Net Dipole | No - dipoles cancel |
Bond Dipoles
Each S=O bond has ΔEN = 0.86 - moderately polar, just like in SO₂. Three identical dipoles radiate outward from the central sulfur at 120° angles.
Molecular Shape & Dipole Cancellation
SO₃ is trigonal planar (120°) because sulfur has no lone pairs - all three positions are occupied by S=O bonds. Compare to SO₂ where a lone pair creates the bent shape.
Net Dipole Moment
Three identical dipoles at 120° in a plane cancel exactly - the same reason BF₃ is nonpolar. SO₃ is nonpolar despite having polar bonds. This contrasts beautifully with SO₂ (bent, polar).
See bond dipoles, partial charges, and net dipole moments on interactive 3D molecules.
Visualize Sulfur Trioxide's Polarity in 3DRelated Topics
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