VSEPR Molecular Shapes in 3D – Bonding Pairs, Lone Pairs and Bond Angles

What it shows

Electron pairs around a central atom repel each other and spread out as far apart as possible: two domains are linear, three trigonal planar, four tetrahedral, five trigonal bipyramidal and six octahedral. The molecular shape is named from the atom positions only. Lone pairs are held by one nucleus, take up more room and push bonding pairs closer together, so the angle falls from 109.5° in CH₄ to 107° in NH₃ and 104.5° in H₂O. Angles shown are measured values for sample molecules, and polarity is judged from the bond dipoles only.

How to use

Start with NH₃ and compare it with CH₄ and H₂O using the buttons for the same number of electron domains. Choose Custom AXₙEₘ and move the Bonding pairs and Lone pairs sliders to build any shape. Tick Lone pairs, Bond angles and Dipole moment to show or hide those features. Drag to rotate, Stop rotating to hold the view, Reset view and Reset to start again.

Parameters you can change

• Molecule Custom AXₙEₘ, BeCl₂, CO₂, BF₃, SO₂, CH₄, NH₃, H₂O, PCl₅, SF₄, ClF₃, XeF₂, SF₆, BrF₅, XeF₄
• Number of bonding pairs (custom) 2–6 pairs
• Number of lone pairs (custom) 0–3 pairs
• Show lone pairs
• Show bond angles
• Show net dipole moment

Questions to explore

1. Why does the bond angle decrease from CH₄ to NH₃ to H₂O, although all three have four electron domains?
2. In SF₄ and ClF₃, do the lone pairs sit in equatorial or axial positions, and why?
3. CO₂ and SO₂ both have polar bonds, so why is only SO₂ a polar molecule?