Molecule Shapes (VSEPR)
Drag bonds and lone pairs onto a central atom, rotate it in 3D, and explore real molecules.
Bonds
Lone pair
Molecule
Geometry name
What the Molecule Shapes (VSEPR) shows
Drag bonds and lone pairs onto a central atom, rotate it in 3D, and explore real molecules. Free, no signup, runs in your browser. Built for molecules, the molecule shapes (vsepr) runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Add bonds and lone pairs around a centre atom to see the 3D shape that minimises repulsion.
How to use the Molecule Shapes (VSEPR)
In the Molecule Shapes (VSEPR), press "+ Single bond", "+ Double bond", "+ Triple bond", "+ Lone pair" to start, reset or change what is happening.
Start with this experiment: Drag two single bonds in, then add two lone pairs. What shape do you get?. Drag any glowing handle, object or slider with your mouse or finger and the Molecule Shapes (VSEPR) responds in real time.
Change one setting at a time and watch which readout moves, then compare it with this idea: Electron groups repel each other and spread as far apart as possible.
Things to try
Drag two single bonds in, then add two lone pairs. What shape do you get?
Turn on Show Bond Angles and Molecule Geometry, then add a lone pair to CH4-like models and watch the angles shrink.
Switch to Real Molecules and compare H2O, NH3 and CH4. All are tetrahedral electron geometry with different shapes.
Can you build a square planar molecule? Hint: four bonds and two lone pairs.
The science behind it
Electron groups repel each other and spread as far apart as possible.
Lone pairs take up more room than bonds and squeeze the bond angles.
Molecular shape is named by the atoms only, while electron geometry counts lone pairs too.
A worked example with real numbers
H₂O: 4 domains (2 bonds, 2 lone pairs): bent, ≈104.5° NH₃: 4 domains (3 bonds, 1 lone pair): trigonal pyramidal, ≈107° CH₄: 4 domains, no lone pairs: tetrahedral 109.5°.
Tips and common mistakes
Tips
- Add lone pairs one at a time to see the angle shrink.
- Compare real molecule mode with model mode.
- Rotate to see the 3D geometry.
Common mistakes
- Lone pairs take more room than bonding pairs.
- Name the shape from atoms only, not from lone pairs.
- A double bond counts as one domain.
Where this is used
Molecular shape controls how enzymes work, how drugs fit receptors, why water is polar, and how materials behave.
Who is this simulation for?
Chemistry and biology students learning bonding and molecular shape, and teachers who need an interactive 3D model instead of a textbook drawing. A good first experiment in the Molecule Shapes (VSEPR): Drag two single bonds in, then add two lone pairs. What shape do you get?. The key relation to keep an eye on: VSEPR: shape follows the number of electron domains (bonds plus lone pairs).
For teachers: project the Molecule Shapes (VSEPR) on the board, let students predict the result, then run it together and test this: Turn on Show Bond Angles and Molecule Geometry, then add a lone pair to CH4-like models and watch the angles shrink. For students: change one thing at a time and write down what changes.
Frequently asked questions
What does VSEPR stand for?
Valence Shell Electron Pair Repulsion. Electron groups around a central atom repel each other, which sets the shape of the molecule.
Why is water bent and not linear?
Oxygen has two bonds and two lone pairs. The four groups arrange tetrahedrally, so the two atoms form a bent shape of about 104.5°.
Is the Molecule Shapes (VSEPR) free to use?
Yes. The Molecule Shapes (VSEPR) is free, needs no signup or download and runs in your web browser. It is part of the Molecules group of AZRS simulations.
Does the Molecule Shapes (VSEPR) work on a phone or tablet?
Yes. The Molecule Shapes (VSEPR) takes touch input as well as mouse input, so you can drag its objects with a finger. A larger screen makes the controls and graphs easier to read.
