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Learning path · 18 parts

Matter & Reactions

Start with what holds two atoms together, then follow reactions through speed, balance, and the transfer of protons and electrons.

About 3 hours of reading · 36 widgets

Start with Atomic Structure and the Periodic Table
  1. Chemistry11 min

    Part 1: Atomic Structure and the Periodic Table

    Electrons do not orbit. They occupy standing-wave probability clouds whose shapes and capacities are fixed by three quantum numbers — and those capacities are exactly why the periodic table has the blocks and row lengths it does.

  2. Chemistry10 min

    Part 2: Radioactivity: Random Decay, Predictable Half-Life

    Why individual radioactive decay is fundamentally random and memoryless, yet a large population halves like clockwork — with the decay law, half-life, decay modes, and dating.

  3. Chemistry10 min

    Part 3: The Periodic Table: Why the Pattern Repeats

    The periodic table is not an arbitrary chart. Ordered by atomic number and shaped by electron configuration, its rows and columns encode why elements repeat their chemistry.

  4. Chemistry10 min

    Part 4: The Mole: Chemistry's Bridge to the Invisible

    The mole is chemistry's counting unit — like a dozen, but 6.022×10²³ strong. It bridges the grams you can weigh and the particles you cannot see.

  5. Chemistry10 min

    Part 5: Spectroscopy: Reading Matter with Light

    Atoms absorb and emit light only at wavelengths set by their electron energy levels, so light carries a fingerprint of composition — the basis of knowing what stars, galaxies, and unknown compounds are made of, remotely.

  6. Chemistry10 min

    Part 6: Why Atoms Bond

    Bring two hydrogen atoms together and they snap into a molecule, releasing energy. The potential-energy curve explains bond length, bond strength, and why covalent and ionic are two ends of one continuum.

  7. Chemistry10 min

    Part 7: Intermolecular Forces and Why Water Is Weird

    The bonds inside a molecule are worth hundreds of kJ/mol; the forces between molecules are worth a handful. Yet it is those humble forces — dispersion, dipole–dipole, hydrogen bonding — that decide whether a substance is a gas, a liquid or a solid, and why ice floats.

  8. Chemistry10 min

    Part 8: Polymers: The Chemistry of Long Chains

    A polymer is any giant molecule built from many repeating monomer units. The same architecture makes plastics, rubber, proteins, and DNA — and structure, not the monomer, sets the properties.

  9. Chemistry10 min

    Part 9: Solutions: Where Does the Sugar Go?

    Dissolving does not destroy a solute — it disperses it. Water surrounds each particle in a hydration shell, but only when forces match ('like dissolves like'), and only up to a saturation limit.

  10. Chemistry10 min

    Part 10: The Ideal Gas Law and Kinetic Theory

    Where the ideal gas law comes from: count the collisions of point particles against the walls, discover that temperature is nothing but average molecular kinetic energy, and read off PV = nRT.

  11. Chemistry10 min

    Part 11: Phase Transitions

    Energy pours into melting ice and the thermometer does not move. The missing joules are buying something other than speed — and following where they go explains latent heat, phase diagrams, and why ice floats.

  12. Chemistry10 min

    Part 12: Reaction Rates and Catalysis

    Collision theory, the activation-energy barrier, and the Arrhenius exponential — how chemistry decides not whether a reaction happens but how fast, and what a catalyst can and cannot change.

  13. Chemistry10 min

    Part 13: Free Energy: Why Reactions Happen

    Diamond spontaneously turns into graphite and yet your ring survives — the gap between those two facts is the whole story of Gibbs free energy, the referee between energy and disorder.

  14. Chemistry10 min

    Part 14: Chemical Equilibrium

    A sealed flask settles at a fixed shade of brown and stays there forever — not because the reaction ended, but because the forward and reverse reactions now run at exactly the same rate.

  15. Chemistry10 min

    Part 15: Le Chatelier's Principle: How Equilibrium Pushes Back

    Le Chatelier's principle predicts how a chemical equilibrium responds to concentration, pressure, and temperature changes — partially counteracting each stress while only heat actually shifts K.

  16. Chemistry10 min

    Part 16: Acids, Bases and pH

    pH is a logarithm, which is why one unit is a factor of ten and why your blood can survive a lifetime of acidic meals. A tour of proton transfer, water's autoionisation, strong versus weak acids, buffers and titration curves.

  17. Chemistry10 min

    Part 17: Redox: The Chemistry of Electron Transfer

    Oxidation is loss of electrons, reduction is gain, and they always happen together. That one idea — tracked with oxidation states — unifies combustion, rusting, batteries, and respiration.

  18. Chemistry10 min

    Part 18: Electrochemistry: How Batteries Work

    Split a redox reaction into two half-cells and the electrons have to detour through your device. That detour is electricity — and its voltage, its limits, and its eventual death are all predictable.