Properties and Uses of Transition Metals

The first-row transition elements from scandium to zinc: their electron configurations and the chromium and copper exceptions; variable oxidation states and catalysis in the Haber and contact processes; complex ions, their ligands, shapes, names and isomers; why their ions are coloured, explained with d-orbital splitting; and how to identify Fe²⁺, Fe³⁺, Cu²⁺ and other ions with sodium hydroxide and ammonia.

2

Extraction of Metals

How the reactivity of a metal decides how it is extracted, with ores, concentration and the Ellingham diagram; carbon reduction in the blast furnace and the extraction of iron, copper, zinc and tin; electrolytic extraction of sodium and aluminium; the processing of tungsten and tantalum; Rwanda's tin, tantalum and tungsten minerals; and the environmental damage extraction causes and how it is prevented.

3

Benzene

The structure of benzene: Kekulé's model, the delocalised model, and the evidence from bond lengths and enthalpies of hydrogenation; its physical properties, uses, toxicity and preparation; how to name benzene compounds and find their positional isomers; why benzene is so stable; and its reactions, with the mechanisms of electrophilic substitution: nitration, halogenation and Friedel–Crafts reactions.

4

Derivatives of Benzene

How substituent groups change the reactivity of the benzene ring and direct new groups to the 2,4- or 3-positions; methylbenzene and other aromatic hydrocarbons, with reactions of the ring and the side chain; phenol, its acidity and its reactions; aromatic aldehydes, ketones and benzoic acid; and nitrobenzene, phenylamine and azo dyes, with their uses and safety.

5

Polymers and Polymerisation

How small monomers join into long chains by addition and condensation polymerisation; how to draw repeat units and find the monomer; natural and synthetic polymers, thermoplastics, thermosets and elastomers, and how chain structure controls properties; the vulcanisation of rubber; and the uses of polymers, the damage plastic waste does, and how Rwanda and the world manage it.

6

Solvent Extraction and Colligative Properties

How a solute shares itself between two immiscible solvents, and how the partition coefficient is used to design solvent extractions; Raoult's law for ideal solutions and the positive and negative deviations of real ones; fractional distillation, azeotropes and steam distillation; and the colligative properties (lowering of vapour pressure, elevation of boiling point, depression of freezing point and osmotic pressure), used to find molar masses and applied in medicine, food and water treatment.

7

Chemical Equilibrium

Reversible reactions and the features of dynamic equilibrium; the law of mass action and the equilibrium constants Kc and Kp, with ICE-table calculations, the relation between Kp and Kc, and the reaction quotient Q; Le Chatelier's principle, explained through Q and K; and the compromise conditions chosen for the Haber and Contact processes.

8

pH of Acidic and Alkaline Solutions

The Arrhenius, Brønsted–Lowry and Lewis theories of acids and bases; the ionic product of water, and the pH and pOH of strong acids and bases; the degree of ionisation, Ka, Kb, pKa and pKb of weak acids and bases, and the pH of their solutions; salt hydrolysis and the pH of salt solutions; and buffer solutions, how they work and the Henderson–Hasselbalch equation.

9

Indicators and Titration Curves

How acid–base indicators work as weak acids, why each changes colour over a range of about pKIn ± 1, how the pH changes during strong and weak acid–base titrations, how to read the equivalence point, half-equivalence point and buffer region from a titration curve, and how to choose the right indicator for each type of titration.

10

Solubility and Solubility Product of Sparingly Soluble Salts

Solubility and molar solubility; unsaturated, saturated and supersaturated solutions; the dissolution equilibrium of sparingly soluble salts and the solubility product, Ksp, with its link to solubility; using the ionic product to predict precipitation and to separate ions by fractional precipitation; and how common ions, pH and complex ion formation change solubility, with applications in analysis, water treatment and medicine.

11

Electrochemical Cells and Applications

How galvanic cells turn the energy of redox reactions into electricity; half-cells, salt bridges and cell diagrams; the standard hydrogen electrode and standard electrode potentials; calculating cell emf and predicting whether a redox reaction is feasible; the effect of concentration on emf (the Nernst equation); corrosion of iron and how it is prevented; batteries and fuel cells; and how galvanic cells differ from electrolytic cells.

12

Factors That Affect the Rate of Reactions

What reaction kinetics studies and how a rate is defined, measured and expressed for every species in an equation; average, instantaneous and initial rates from concentration–time data; how concentration, pressure, surface area, temperature, catalysts, light and the nature of the reactants change a rate, explained with collision theory and the Maxwell–Boltzmann distribution; and the Arrhenius equation, used to find activation energies and to predict rate constants at other temperatures.

13

Rate Laws and Measurements

Collision theory and transition state theory; how rates are measured by following mass, gas volume, colour, titration and conductivity; rate equations, orders and rate constants found by the initial-rates method; integrated rate laws, linear plots and half-lives for zero-, first- and second-order reactions; the difference between order and molecularity; and how a proposed reaction mechanism, with its rate-determining step, is tested against an experimental rate law.

14

Radioactivity

Radioactivity and radioisotopes, and how nuclear reactions differ from chemical reactions; alpha, beta-minus, positron, electron-capture and gamma emission; balancing nuclear equations in mass number and atomic number, decay series and artificial transmutation; the neutron–proton ratio and the band of stability; first-order decay, half-life and radiocarbon dating; nuclear fission and fusion; and the health hazards, safe handling and uses of radioisotopes such as carbon-14, phosphorus-32, cobalt-60 and iodine-131.

Units