Introduction
Chemistry is much easier to understand when you can explore what is happening for yourself.
The interactive simulations on this page have been developed by the PhET Interactive Simulations project at the University of Colorado Boulder.
They allow you to change variables, manipulate particles and molecules, make predictions and immediately see the results.
I have selected simulations that I think are particularly useful for students studying GCSE and A-level Chemistry.
Don't simply watch what happens.
Experiment.
Predict.
Change one thing at a time.
Ask yourself why the result changes.
Used in this way, these simulations can help turn an abstract chemical idea into something you can visualise and understand.
Each link below takes you to a FranklyChemistry page where you can explore the simulation together with some guidance on how to get the most from it.
Explore how bonding pairs and lone pairs determine molecular geometry and bond angles using an interactive 3D model.
Explore how electronegativity and molecular shape combine to determine bond polarity and the overall polarity of a molecule.
Explore how different isotopes of an element and their relative abundances combine to determine its relative atomic mass.
Explore how acid and base strength, concentration and ionisation affect pH, electrical conductivity and the particles present in aqueous solution.
Explore how changes in temperature, volume and number of particles affect gas pressure, and relate these changes to the motion and collisions of gas particles.
Explore how balanced equations determine reacting proportions, and investigate limiting reactants, excess reactants and the maximum amount of product that can be formed.
Explore how adding solute, dilution, evaporation and saturation affect the concentration of a solution.
Explore how attractive and repulsive forces between atoms vary with distance, and how their balance determines equilibrium separation and minimum potential energy.
Explore how pH relates to hydrogen-ion and hydroxide-ion concentrations, and discover why a change of one pH unit represents a tenfold change in H⁺ concentration.
Explore how Rutherford’s alpha-particle scattering experiment provided evidence for a tiny, dense, positively charged nucleus and disproved the plum pudding model.
Explore how conservation of mass requires the same number of atoms of each element on both sides of a chemical equation, and practise balancing equations using the smallest whole-number coefficients.
Explore how particle arrangement, movement and intermolecular attractions change between solids, liquids and gases, and investigate the effects of temperature and pressure on physical state.
Explore how different models of the hydrogen atom account for its line spectrum, and investigate how absorption and emission provide evidence for quantised electronic energy levels.