ZIMSEC · O Level
Chemistry
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Form 3 5 topics
- Particles and atomic structure All matter is made of moving particles. Heating gives them more energy: solids melt, liquids boil. Diffusion and Brownian motion are evidence that particles move.
- Chemical bonding and structure Atoms bond to get a full outer shell.
- Formulae, equations and the mole Use valencies or ion charges: Ca²⁺ and Cl⁻ give CaCl₂; Al³⁺ and O²⁻ give Al₂O₃.
- Acids, bases and salts Neutralisation: H⁺(aq) + OH⁻(aq) → H₂O(l)
- The periodic table: groups and trends Elements are arranged by proton number. Elements in a group have the same number of outer electrons and similar properties.
Form 4 5 topicsExam year
- Electrolysis Electrolysis is the decomposition of an ionic compound, molten or in solution, by passing electricity through it.
- Energy changes and rates of reaction Particles must collide with enough energy (the activation energy). The rate increases with:
- Metals and their extraction K, Na, Ca, Mg, Al, (C), Zn, Fe, Pb, (H), Cu, Ag, Au. More reactive metals displace less reactive ones from solutions of their salts, e.g. Zn + CuSO₄ → ZnSO₄ + Cu.
- Non-metals, air and water About 78% nitrogen, 21% oxygen, 0.04% carbon dioxide, plus argon and water vapour. Pollutants: carbon monoxide (incomplete combustion, poisonous), sulfur dioxide (burning coal, acid rain), nitrogen oxides (car engines), particulates.
- Organic chemistry Organic compounds contain carbon. A homologous series has the same general formula, similar chemical properties and a gradual change in physical properties.