VSEPR (Valence Shell Electron Pair Repulsion) theory predicts the 3D shape of molecules by minimizing repulsions between electron pairs around a central atom. Lone pairs compress bond angles below ideal values, giving molecules like water (H₂O) a bent shape instead of linear.
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3D Geometry Diagram
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| Steric # | Bonds | Lone Pairs | Electron Geometry | Molecular Geometry | Bond Angle | Example |
|---|---|---|---|---|---|---|
| 2 | 2 | 0 | Linear | Linear | 180° | CO₂ |
| 3 | 3 | 0 | Trigonal planar | Trigonal planar | 120° | BF₃ |
| 3 | 2 | 1 | Trigonal planar | Bent | ~119° | SO₂ |
| 4 | 4 | 0 | Tetrahedral | Tetrahedral | 109.5° | CH₄ |
| 4 | 3 | 1 | Tetrahedral | Trigonal pyramidal | 107° | NH₃ |
| 4 | 2 | 2 | Tetrahedral | Bent | 104.5° | H₂O |
| 5 | 5 | 0 | Trigonal bipyramidal | Trigonal bipyramidal | 90°/120° | PCl₅ |
| 5 | 4 | 1 | Trigonal bipyramidal | Seesaw | ~90°/120° | SF₄ |
| 5 | 3 | 2 | Trigonal bipyramidal | T-shaped | ~87.5° | ClF₃ |
| 5 | 2 | 3 | Trigonal bipyramidal | Linear | 180° | XeF₂ |
| 6 | 6 | 0 | Octahedral | Octahedral | 90° | SF₆ |
| 6 | 5 | 1 | Octahedral | Square pyramidal | ~84.8° | BrF₅ |
| 6 | 4 | 2 | Octahedral | Square planar | 90° | XeF₄ |
How to Use the Molecular Geometry Visualizer
VSEPR theory is the most widely taught method for predicting molecular geometry. This visualizer generates 3D-like SVG diagrams for 25+ molecules, showing electron geometry, molecular geometry, bond angles, hybridization, and polarity in one view.
Step 1: Select a Molecule
Click any molecule in the quick-select grid or type a formula in the input box. For example, select "H₂O" to see water's bent geometry. Common educational molecules include CH₄ (tetrahedral), NH₃ (trigonal pyramidal), CO₂ (linear), and SF₆ (octahedral).
Step 2: Read the SVG Diagram
The diagram shows bond types using chemistry notation: solid lines (—) for bonds in the plane, solid wedge bonds (▶) for bonds coming toward you, and dashed wedge bonds for bonds pointing away. Lone pairs appear as double-dot pairs. Bond angles are labeled with arc lines and degree measurements.
Step 3: Understand Electron vs. Molecular Geometry
Compare the two geometry fields: electron geometry includes lone pairs, molecular geometry describes only atom positions. For NH₃: electron geometry is tetrahedral (4 electron groups around N), but molecular geometry is trigonal pyramidal (the 3 H atoms form a pyramid base, with N at the apex and the lone pair above). The lone pair is present but invisible in the molecular geometry.
Predicting Bond Angles
The ideal bond angles are: 180° (linear), 120° (trigonal planar), 109.5° (tetrahedral), 90°/120° (trigonal bipyramidal), 90° (octahedral). Lone pairs compress these angles: each lone pair reduces bond angles by about 2-2.5°. Water has 2 lone pairs compressing 109.5° by ~5° to 104.5°; ammonia has 1 lone pair compressing to 107°.
Using the VSEPR Reference Table
The collapsible reference table at the bottom shows all 13 common geometries with their steric numbers, bonding pairs, lone pairs, bond angles, and example molecules. Use this as a study guide — it covers every geometry from linear (steric 2) to square planar (steric 6, 4 bonds, 2 lone pairs).
FAQ
Is the Molecular Geometry Visualizer free?
Yes, completely free. No signup or account required. All geometry diagrams are generated in your browser.
Is my data private?
Yes. All calculations run locally in your browser. No data is sent to any server.
What is VSEPR theory?
VSEPR (Valence Shell Electron Pair Repulsion) theory predicts molecular geometry by minimizing repulsions between electron pairs around a central atom. Lone pairs repel more strongly than bonding pairs, which compresses bond angles below ideal values.
What is the difference between electron geometry and molecular geometry?
Electron geometry considers all electron pairs (bonding + lone pairs) around the central atom. Molecular geometry describes only the arrangement of atoms (ignoring lone pairs). For example, water has tetrahedral electron geometry but bent molecular geometry because two lone pairs occupy tetrahedral positions.
Why is water's bond angle 104.5° instead of 109.5°?
The ideal tetrahedral angle is 109.5° (as in CH4). Water has two lone pairs on oxygen, and lone pairs repel more than bonding pairs, compressing the H-O-H angle from 109.5° to 104.5°. Similarly, NH3 is compressed from 109.5° to 107° by one lone pair.
How do I determine hybridization from geometry?
Hybridization directly follows the steric number (bonding groups + lone pairs): steric 2 = sp, steric 3 = sp2, steric 4 = sp3, steric 5 = sp3d, steric 6 = sp3d2. The tool shows hybridization for each molecule automatically.
How is molecular polarity determined?
A molecule is polar if it has polar bonds AND the bond dipoles don't cancel due to geometry. Symmetric molecules like CO2 (linear), BF3 (trigonal planar), and SF6 (octahedral) are nonpolar despite polar bonds because the dipoles cancel. Bent (H2O), pyramidal (NH3), and seesaw (SF4) molecules are polar.