Alkane and alkene molecules – 3D ball-and-stick models
Integrated ScienceChemical ReactionsAges 14–15
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Chemical Reactions
Ball-and-stick models of methane CH₄, ethane C₂H₆, propane C₃H₈ and ethylene C₂H₄ spin freely in space; drag to rotate them by hand. The side panel counts C–H bonds, single C–C bonds and double C=C bonds, shows the bond angle, the structural formula, and the balanced combustion equation (plus the bromine addition reaction for the alkene) so you can tell saturated and unsaturated hydrocarbons apart.
Lesson: Alkanes; Alkenes; Introduction to organic compounds
What it shows
Carbon forms four covalent bonds. In alkanes such as methane, ethane and propane every bond is single, so the molecules are saturated and each carbon sits at the centre of a tetrahedron with bond angles of about 109.5°. Ethylene (ethene), the simplest alkene, contains a C=C double bond, which makes it unsaturated and flat, with angles near 120°. All hydrocarbons burn completely in oxygen to give CO₂ and H₂O, but only the alkene takes part in addition with bromine, decolourising bromine water: the standard test for a C=C bond.
How to use
Choose a Molecule and drag it to rotate; use Stop rotating for a steady view. Ask students to count the bonds on the model first, then check against the side panel. Switch off Show bond sticks to see the atoms alone, and switch on Show combustion equation to compare the balanced equations. Going from methane to ethane to propane shows the chain growing by CH₂ each time, while comparing ethane with ethylene highlights the double bond.
Parameters you can change
- Molecule Methane CH₄, Ethane C₂H₆, Propane C₃H₈, Ethylene C₂H₄
- Show bond sticks (off: atoms only)
- Auto-rotate
- Rotation speed 10–120 °/s
- Show combustion equation
Questions to explore
- How many bonds does each carbon atom form in ethane and in ethylene, and how are they arranged in space?
- Why does ethylene decolourise bromine water while ethane does not?
- Using the side panel, what is the balanced equation for the complete combustion of propane?
