How to Memorise IGCSE Chemistry Reactions and Tests (Without Forgetting Them in the Exam)

Roughly a quarter of the marks in a 0620 session reward pure, accurate recall: which reagent, which colour, which gas, which order in the reactivity series. These are the cheapest marks on the paper (no problem-solving, no calculation), and they are still lost in bulk, because students “learn” the tables by staring at them. Staring stores nothing. Here is what does.

Flashcards for the qualitative analysis tables

The qualitative analysis section is a memory database: cation tests, anion tests, gas tests, flame colours. Build it as flashcards, one fact per card, and card it in both directions:

• Front: “Test for ammonium ions” → Back: “Add aqueous sodium hydroxide, warm; ammonia gas turns damp red litmus blue.”
• Front: “White precipitate with aqueous sodium hydroxide, soluble in excess” → Back: “Zinc ions or aluminium ions: distinguish with aqueous ammonia (zinc dissolves in excess ammonia, aluminium does not).”

The reverse direction matters because Paper 6 routinely gives the observation and asks for the ion. Students who only learned ion → result freeze when the question runs result → ion.

Keep the deck under about 60 cards. The full set for qualitative analysis fits comfortably: 8 cation tests, 5 anion tests, 4 gas tests, 4 flame colours, plus the two tests for water.

Colour changes: give every colour an anchor

Colours are where recall gets slippery, because “blue” and “green” and “white” repeat across the syllabus. The fix is a concrete anchor per colour fact (the stranger, the stickier):

• Copper(II) hydroxide: light blue precipitate. Copper compounds are the “blue family”; hydrated copper(II) sulfate crystals are blue, the precipitate is blue.
• Iron(III) hydroxide: red-brown. Think rust. Rust is hydrated iron(III) oxide, so the link is chemistry, not coincidence.
• Iron(II) hydroxide: green. Iron(II) is the “younger” iron: green, unripe, and it browns with age as air oxidises it to iron(III).
• Potassium flame: lilac. “K for King, kings wear purple.”
• Anhydrous copper(II) sulfate: white to blue with water. White paper turns blue when you write on it with water. Picture it, absurd as it is.
• Acidified potassium manganate(VII): purple to colourless with a reducing agent. Not “clear”: colourless. Mark schemes punish “clear”.

An anchor takes 20 seconds to build and survives exam adrenaline far better than a bare fact.

The reactivity series: one sentence, permanently

Extended candidates need the order cold: K, Na, Ca, Mg, Al, C, Zn, Fe, H, Cu, Ag, Au. A sentence mnemonic does it:

“Please Send Cats, Monkeys And Cute Zebras Into Hot Countries Signed Gold.”

Say it aloud three days running while writing the symbols underneath, and the order sets. Then attach the two structural facts that questions actually test: metals above carbon are extracted by electrolysis, metals below carbon by reduction with carbon; and a metal displaces anything below it from solution. The series is not trivia. It decides answers across metals extraction, displacement and the thermal stability questions.

Organic chemistry: learn the map, not the list

Students try to memorise organic reactions as isolated sentences and drown. The syllabus organic content is a small map: draw it once on A4 and redraw it from memory weekly:

• Alkane → (substitution with Cl2, UV light) → chloroalkane
• Alkene → (addition of H2, nickel catalyst) → alkane; → (addition of steam, catalyst) → alcohol; → (addition of Br2) → dibromo compound, and the orange-to-colourless bromine water test
• Ethanol → (oxidation by acidified potassium manganate(VII), or bacterial oxidation) → ethanoic acid
• Ethanoic acid + ethanol → (concentrated sulfuric acid catalyst) → ester (ethyl ethanoate)
• Ethene ↔ poly(ethene) by addition polymerisation

Eleven arrows, give or take your route’s Supplement content. Each redraw is a retrieval event; by the fourth attempt the map draws itself. The same approach works for the organic chemistry naming patterns: card the functional groups (-ane, -ene, -ol, -oic acid) rather than memorising compound names one by one.

The retrieval schedule that makes it permanent

Technique without a schedule decays. Use expanding intervals:

Review	When	What
1	Day you make the cards	Whole deck, both directions
2	Day 3	Whole deck; wrong cards flagged
3	Day 7	Flagged cards twice, rest once
4	Day 14	Whole deck
5+	Weekly until the exam	10 minutes, standing, out loud

Two rules keep it honest. First, answer out loud or on paper before flipping the card: recognising the answer is not recalling it. Second, anything wrong twice in a row gets a new, stronger anchor; the old one wasn’t doing its job.

Then connect memory to marks: once the deck is solid, do past-paper questions on the same content so you practise deploying the facts inside 0620 phrasing. The common exam mistakes guide shows how recalled facts still lose marks when the wording is loose: “bubbles” instead of “effervescence”, “clear” instead of “colourless”.

If you have built the deck, kept the schedule for three weeks, and the colours still scramble under timed conditions, the problem is usually structural: confusable facts learned in the wrong order, with no anchors. That is fixable in a single session with someone who has watched hundreds of students make the identical confusions. A free 1-hour trial lesson with one of our Chemistry specialists will rebuild your weakest table with you, live, before you commit to anything.

The memory marks are the most controllable marks on the paper. Card them, anchor them, schedule them, and walk into the exam owning a quarter of the grade before the first hard question appears.