The map of chemistry
Eight families of ideas, in the order schools teach them. Every lesson starts with something real and ends at the atoms, with a simulation you can push around. The ones still being written are listed so you can see where the site is going.
Atoms and the periodic table
What an atom is made of, where its electrons are, and why the table has the shape it does.
- Where are the electrons in an atom?Shells, subshells and orbitals, filled one electron at a time.GCSE and A-level · Core and Deeper
- Why do metals burn with different colours?Electrons jump up, fall back and give out light at exact wavelengths.GCSE and A-level · Core and Deeper
- Why is chlorine’s mass 35.45 and not a whole number?Isotopes and relative atomic mass.GCSE · being written
- Why does reactivity change down a group?Atomic radius, shielding and ionisation energy.GCSE and A-level · being written
Bonding and shape
Why atoms stick together, and why molecules come out the shapes they do.
- Why does salt dissolve in water?Water molecules pull the crystal apart, one ion at a time.GCSE · Core and Deeper
- Why is a water molecule bent?Electron pairs push each other as far apart as they can.GCSE and A-level · Core and Deeper
- What holds a molecule together?Shared pairs of electrons and dot-and-cross diagrams.GCSE · being written
- Why do metals conduct electricity?Positive ions in a sea of delocalised electrons.GCSE · being written
- Why does water boil at 100 °C and methane at −162 °C?Forces between molecules, including hydrogen bonds.A-level · being written
States and mixtures
Solids, liquids, gases and solutions, explained by particles.
- What happens to particles when ice melts?The particle model of solids, liquids and gases.GCSE · being written
- How does chromatography separate inks?Mixtures, solvents and Rf values.GCSE · being written
Amount of substance
Counting atoms by weighing them: the mole and everything built on it.
- How do you count atoms you can’t see?The mole: a number of particles you can weigh out.GCSE and A-level · Core and Deeper
- What does 0.1 mol/dm³ actually mean?Concentration, dilution and titration sums.GCSE and A-level · being written
- Why do reactions never give 100% yield?Percentage yield and atom economy.GCSE · being written
Energy and change
Where the heat in a reaction comes from, and where it goes.
- Why do some reactions get hot?Breaking bonds takes energy; making them gives it out.GCSE · being written
- How can you measure a reaction you can’t do?Hess’s law and enthalpy cycles.A-level · being written
Rates and equilibrium
Why some reactions are fast, some slow, and some never quite finish.
- Why do reactions go faster when it’s hot?More collisions, and many more of them hard enough to react.GCSE and A-level · Core and Deeper
- Why does a reaction push back when you change it?Le Chatelier’s principle, shown with molecules you can count.GCSE and A-level · Core and Deeper
- How does a catalyst speed things up without being used up?A different route with a lower activation energy.GCSE and A-level · being written
Acids, bases and electrochemistry
Hydrogen ions, pH, neutralisation and the chemistry inside a battery.
- What does pH actually measure?Each step on the scale is ten times more hydrogen ions.GCSE and A-level · Core and Deeper
- What happens when an acid meets an alkali?H⁺ and OH⁻ make water, and a salt is left.GCSE · being written
- How does a battery make electricity?Redox, half-equations and electrode potentials.GCSE and A-level · being written
Organic chemistry
The chemistry of carbon compounds, and how their reactions happen arrow by arrow.
- Why do all alcohols behave alike?Functional groups and homologous series.GCSE · being written
- What do curly arrows mean?Electron pairs moving in a reaction mechanism.A-level · being written
- Why does bromine water lose its colour with alkenes?Electrophilic addition, step by step.A-level · being written