Subject Guide
Chemistry
Chemistry is accuracy + method. High marks come from clean steps, correct units/sig figs, and correct explanations.
High score rule: You don’t “know chem” unless you can do questions without notes and explain why each step works.
Assessment (Papers)
Exact paper details can vary by syllabus year. Train these skills consistently.
Paper 1
Fast MCQ. Definitions + calculations + tiny traps.
- Eliminate wrong options using units/dimensions.
- Know common definitions precisely.
- Speed drills weekly.
Paper 2
Short + extended response. Calculations + explanations.
- Show steps clearly for method marks.
- Units every line; correct sig figs at the end.
- Use correct chemistry language (oxidation, equilibrium, etc.).
Paper 3
Data + practical/option.
- Describe trends first, then explain using chem terms.
- Know lab errors + improvements.
- Practice interpreting unfamiliar scenarios.
Best Study Method (Chem)
- 3–5x/week: exam questions (topic sets → mixed sets).
- Daily (short): key definitions + equations recall.
- Weekly: 1 timed mixed set.
- After marking: write the rule you broke (units, sig figs, concept).
Chem mistake pattern: students lose marks from “presentation” errors (sig figs, missing units, wrong rounding).
Fix with a checklist at the end of every question.
Calculation Discipline (Method Marks)
- Write the formula before numbers.
- Substitute with brackets (prevents sign mistakes).
- Units every line (and cancel units).
- Sig figs only at the end (don’t round mid-way).
End-of-question checklist: units? sig figs? reasonable magnitude? sign? correct variable?
Common Mark Traps (Chem)
Trap 1: Sig figs
Rounding too early or wrong sig figs.
Fix: keep full calculator value → round at the end only.
Trap 2: Units
Forgetting units loses easy marks.
Fix: write units every line. Cancel units like algebra.
Trap 3: Definitions
Almost-right wording isn’t accepted.
Fix: memorize precise markscheme phrasing for key definitions.
Explanation Skills (for Paper 2/3)
- State the principle: collision theory, Le Châtelier’s principle, electronegativity, etc.
- Apply it: explain how it changes the system.
- Conclude: what happens to rate/equilibrium/energy/pH.
Markscheme language tip: use “increases/decreases” with the correct variable:
concentration, rate, yield, enthalpy, entropy, lattice energy, etc.
Quick Practice Checklist
- Can I do 10 mixed calculation questions in one sitting?
- Can I state + use definitions (acid/base, rate, enthalpy, equilibrium)?
- Do I have an error list (sig figs, units, sign errors, concept errors)?
- Can I explain changes using principles (Le Châtelier, collision theory)?