The unit in one line
The elements themselves: how each one is prepared, what proves it is there, and what it is used for. 10 of Chemistry's 50 questions over only three chapters, which makes it the densest unit in the subject — more questions per chapter than anything else on the paper.
Read in this order
- Chemistry of non-metals (15 min) — hydrogen and heavy water, the classification of oxides, ozone, ammonia, phosphine and nitric acid, the halogens and their hydracids, carbon allotropes and carbon monoxide, and the sulphur compounds. Every substance on the preparation, properties, test and use pattern.
- Chemistry of metals (16 min) — metallurgy from ore to refined metal, the alkali and alkaline-earth trends, the transition metals and their complexes, the extraction of copper, zinc, mercury, silver and iron, steel and corrosion.
- Bio-inorganic chemistry (11 min) — the ions life runs on, what each does and what its deficiency causes, the sodium-potassium pump, and heavy-metal poisoning with its antidotes.
About 40 minutes in all. Read the first two in order: the metals chapter assumes the redox language the non-metals chapter uses. The physiology behind the third is in Zoology's Endocrinology and Circulatory system.
How it is asked
MEC sets the paper roughly half recall, a third understanding and a fifth application. This unit leans harder on recall than any other: a reagent, a catalyst, a flame colour, a confirmatory precipitate. Understanding is why concentrated sulphuric acid dehydrates but dilute does not, or why a transition metal is coloured at all. Application is usually an identification — a gas turns starch-iodide paper blue, a solution gives a deep blue with excess ammonia — worked backwards to the substance.
Then practise
Each chapter has a fixed-length chapter test under Practice › Topics, drawn from questions written to that chapter's scope. Sit it after reading; a second sitting a week later shows whether it stuck.