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VSEPR Molecular Geometry Calculator & Chart
Enter a formula, ion, name or SMILES to get its VSEPR shape. You get the AXE class, steric number, electron and molecular geometry, bond angles, hybridization and polarity, plus a rotatable 3D model with the lone pairs drawn as lobes.
VSEPR chart: all molecular geometries (steric number 2–7)
This chart gives every common VSEPR shape. X = atoms bonded to the central atom A, E = lone pairs on A. Double and triple bonds count as one domain.
| Steric no. | AXE | Bonds | Lone pairs | Electron geometry | Molecular geometry | Ideal angle | Hybrid. | Examples |
|---|---|---|---|---|---|---|---|---|
| 2 | AX2 | 2 | 0 | Linear | Linear | 180° | sp | CO2, BeCl2 |
| 3 | AX3 | 3 | 0 | Trigonal planar | Trigonal planar | 120° | sp² | BF3, SO3, NO3− |
| 3 | AX2E | 2 | 1 | Trigonal planar | Bent | <120° (≈117°) | sp² | SO2, O3, NO2− |
| 4 | AX4 | 4 | 0 | Tetrahedral | Tetrahedral | 109.5° | sp³ | CH4, NH4+, SO42− |
| 4 | AX3E | 3 | 1 | Tetrahedral | Trigonal pyramidal | <109.5° (≈107°) | sp³ | NH3, PCl3, H3O+ |
| 4 | AX2E2 | 2 | 2 | Tetrahedral | Bent | <109.5° (≈104.5°) | sp³ | H2O, OF2, H2S |
| 5 | AX5 | 5 | 0 | Trigonal bipyramidal | Trigonal bipyramidal | 90°, 120°, 180° | sp³d | PCl5, AsF5 |
| 5 | AX4E | 4 | 1 | Trigonal bipyramidal | Seesaw | <90°, <120° | sp³d | SF4, TeCl4 |
| 5 | AX3E2 | 3 | 2 | Trigonal bipyramidal | T-shaped | <90° | sp³d | ClF3, BrF3 |
| 5 | AX2E3 | 2 | 3 | Trigonal bipyramidal | Linear | 180° | sp³d | XeF2, I3− |
| 6 | AX6 | 6 | 0 | Octahedral | Octahedral | 90°, 180° | sp³d² | SF6, PF6− |
| 6 | AX5E | 5 | 1 | Octahedral | Square pyramidal | <90° | sp³d² | BrF5, IF5 |
| 6 | AX4E2 | 4 | 2 | Octahedral | Square planar | 90° | sp³d² | XeF4, ICl4− |
| 7 | AX7 | 7 | 0 | Pentagonal bipyramidal | Pentagonal bipyramidal | 72°, 90° | sp³d³ | IF7 |
Lone pairs always go where they have the most room. In a trigonal bipyramid they sit in the equatorial positions (seesaw, T-shaped, linear). In an octahedron, two lone pairs sit opposite each other (square planar).
How to use the VSEPR calculator
- Type a formula (
PCl5), an ion with its charge (NO3-,SO4^2-) or a name (ammonia). For bigger molecules, paste a SMILES string (CC(=O)O) and pick the atom you want to analyse. - The tool counts valence electrons and draws the Lewis structure with the same engine as our Lewis structure generator. Then it counts the bonding domains and lone pairs on the central atom.
- Read the AXE class, electron and molecular geometry, bond angle, hybridization and polarity, with every step shown.
- Rotate the 3D model to see where the lone pairs (purple lobes) sit and how they squeeze the bond angles.
Worked examples
Water, H2O (AX2E2)
8 valence e⁻: 2 O–H bonds + 2 lone pairs = 4 domains (tetrahedral electron geometry).
Bent, 104.5°, sp³, polar
Sulfur tetrafluoride, SF4 (AX4E)
34 e⁻: 4 S–F bonds + 1 lone pair = 5 domains. The lone pair sits equatorial.
Seesaw, sp³d, polar
Xenon tetrafluoride, XeF4 (AX4E2)
36 e⁻: 4 Xe–F bonds + 2 lone pairs opposite each other = 6 domains.
Square planar, 90°, nonpolar
Carbonate, CO32− (AX3)
24 e⁻: one C=O and two C–O⁻ (resonance). 3 domains, no lone pairs on C.
Trigonal planar, 120°, sp²
VSEPR theory in brief
Valence Shell Electron Pair Repulsion (VSEPR) theory says that the electron domains around a central atom repel each other and spread out as far as possible. A domain is a single, double or triple bond, or a lone pair. The steric number (bonded atoms + lone pairs) fixes the electron geometry. The positions of the atoms alone give the molecular geometry.
Steric number = (atoms bonded to A) + (lone pairs on A)
Repulsion order and bond angles
Repulsion strength runs lone pair–lone pair > lone pair–bond pair > bond pair–bond pair. That is why the angle shrinks from 109.5° (CH4) to 107° (NH3) and 104.5° (H2O). Heavier central atoms show even smaller angles (PH3 93.5°, H2S 92°). Multiple bonds also take up more room, which is why the H–C–H angle in formaldehyde is 116.5° rather than 120°.
Named shapes
Trigonal pyramidal: NH3, PCl3. Bent: H2O (AX2E2) or SO2 (AX2E). Seesaw: SF4. T-shaped: ClF3. Square pyramidal: BrF5. Square planar: XeF4. Trigonal bipyramidal: PCl5. Octahedral: SF6.
Limits of the model
VSEPR works best for main-group molecules with one central atom. Radicals such as NO2 have an odd electron that acts as a smaller domain, which gives a 134° angle. Lone pairs that join a π system (amides, pyrrole, aniline) flatten the atom towards sp². Transition-metal complexes follow crystal field and ligand field theory instead.
Need the full structure? Draw any molecule in the MolDraw editor, copy its SMILES and paste it here to get the geometry at each atom. You can also view it in 3D.
Open MolDraw editorFrequently asked questions
What is VSEPR theory?
Valence Shell Electron Pair Repulsion (VSEPR) theory says electron domains around a central atom (bonds and lone pairs) push each other as far apart as possible. The number of domains sets the electron geometry; the positions of the atoms alone give the molecular geometry.
How do you find the molecular geometry of a molecule?
Draw the Lewis structure, count the atoms bonded to the central atom (X) and its lone pairs (E). Their sum is the steric number. Use the VSEPR chart: e.g. AX3E (3 bonds, 1 lone pair) is trigonal pyramidal, like NH3.
What is the difference between electron geometry and molecular geometry?
Electron geometry includes lone pairs as positions; molecular geometry describes only where the atoms are. Water has a tetrahedral electron geometry but a bent molecular geometry.
Do double and triple bonds count as one electron domain?
Yes. In VSEPR a single, double or triple bond to the same atom counts as one domain, so CO2 (two double bonds) is linear like BeCl2.
Why is the bond angle in NH3 107° and in H2O 104.5°?
Lone pairs take up more space than bonding pairs and push the bonds closer together. NH3 has one lone pair (107°), H2O has two (104.5°), compared with 109.5° in CH4.
What shape is trigonal pyramidal?
Trigonal pyramidal (AX3E) has three atoms and one lone pair on a tetrahedral electron geometry, like NH3, PCl3 and H3O+. Bond angles are slightly below 109.5°.
What is a seesaw shape?
Seesaw (AX4E) has four atoms and one lone pair on a trigonal bipyramid. The lone pair sits in an equatorial position, as in SF4 and TeCl4.
How do you know if a molecule is polar from its shape?
If the shape is symmetric (linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral, square planar) and all outer atoms are the same, bond dipoles cancel and it is nonpolar. Lone pairs on the central atom or different outer atoms usually make it polar.
How is hybridization related to steric number?
Steric number 2 = sp, 3 = sp2, 4 = sp3, 5 = sp3d, 6 = sp3d2. This is the textbook model; for hypervalent molecules like SF6 modern theory does not need d orbitals.