The papers and your route

📋The five papers

• Paper 1 — Multiple Choice. 1 hour 15 minutes, 40 marks, 40 four-choice questions on the AS content. 31% of the AS Level, 15.5% of the A Level. Tests AO1 and AO2 equally.
• Paper 2 — AS Level Structured Questions. 1 hour 15 minutes, 60 marks, on the AS content. 46% of the AS Level, 23% of the A Level — the largest single component of the AS. Tests AO1 and AO2 equally.
• Paper 3 — Advanced Practical Skills. A laboratory practical test, 2 hours, 40 marks. 23% of the AS Level, 11.5% of the A Level. Entirely AO3: titrations, rates and enthalpy measurements, and qualitative analysis.
• Paper 4 — A Level Structured Questions. 2 hours, 100 marks, on the A Level content, with AS knowledge required throughout. 38.5% of the A Level, the largest component of all. Tests AO1 and AO2 equally.
• Paper 5 — Planning, Analysis and Evaluation. A written paper, 1 hour 15 minutes, 30 marks. 11.5% of the A Level. Entirely AO3, and the context may lie outside the syllabus content — the paper is testing how you design and judge an experiment, not what you remember.

Two things follow from those figures. Paper 2 is worth half as much again as Paper 1 at AS, on the same content, because structured questions can ask you to explain, calculate with working and write mechanisms. And at A Level, Paper 4 alone is worth exactly as much as Papers 1 and 2 together (38.5% against 15.5% + 23%) — the fifteen A Level topics carry as much weight as all twenty-two AS topics.

🔄The three routes

• Route 1 — AS Level only. Papers 1, 2 and 3, all in the same exam series. Graded a to e.
• Route 2 — A Level staged over two years. Year 1: Papers 1, 2 and 3. Year 2: Papers 4 and 5, carrying forward the AS marks subject to the rules and time limits in the Cambridge Handbook.
• Route 3 — A Level in one series. All five papers together. Graded A* to E.

If you take the whole A Level and do not reach grade E, you may still be awarded an AS grade, provided you sat all the AS components in that series and did well enough on them.

🎯What the assessment objectives reward

The weightings are the same at AS and at A Level. Papers 1, 2 and 4 are half AO1 and half AO2; Papers 3 and 5 are all AO3. So in the theory papers, half the marks are for applying what you know to something you have not seen — an unfamiliar organic molecule to name and react, a new set of data to process, an equation you have to deduce rather than recall.

That is why reading notes is not enough on its own. Recall gets you AO1; AO2 comes from having done enough questions that the unfamiliar ones feel like variations.

📝Command words

A correct answer to the wrong command word can score nothing. The ones that matter most in chemistry:

• State — express in clear terms. No explanation. Give and Identify are similar: produce or name the answer.
• Define — give a precise meaning. Chemistry definitions are marked word by word: “first ionisation energy” without one mole and gaseous is not a definition.
• Describe — the main features. For a reaction, that usually means the observations and conditions, not the reasons.
• Explain — purposes or reasons: make the relationships clear, say why and/or how, and support it with evidence. If your answer contains no “because” or “so”, you have probably described.
• Suggest — apply your knowledge to a situation where there is a range of valid answers. This is the signal that you are not expected to know the answer, and a reasoned proposal will be credited.
• Deduce — conclude from the information given. Predict — suggest what may happen, based on it.
• Calculate — work it out from the given figures; show working. Determine — establish an answer using the information available, often by reading from a graph.
• Show (that) — structured evidence leading to a given result. You are given the answer; the marks are for the route, so every step must be visible.
• Compare — similarities and/or differences. Contrast — differences only.
• Sketch — a simple freehand drawing showing the key features: a Boltzmann curve with the right shape, a reaction pathway with the activation energy labelled.
• Discuss, Evaluate, Justify, Analyse, Examine, Consider and Demonstrate also appear, mostly on Paper 5. Evaluate means judge the quality or value of something; justify means support a case with evidence.

The 2028–2030 syllabus rewords a few of these slightly — Define is “give a precise meaning”, Explain says “make the relationships between things clear”, Sketch is now explicitly freehand — without changing what they ask for.

📏Units and significant figures cost marks

The syllabus warns that misusing units or significant figures — leaving out a unit, putting a unit on a ratio such as A_r, or quoting too many or too few figures — “is liable to be penalised”. It also says what “appropriate” means: the same number of significant figures as the least precise value you used, or one more. If the data are given to 3 s.f., give your answer to 3 or 4.

Two habits prevent most of these losses:

• Carry full calculator values through a multi-step calculation and round only the final answer. Rounding at each step compounds the error, and a final answer that is out in the third figure loses the accuracy mark.
• Convert units before you substitute. cm³ to dm³ (÷ 1000) for concentrations, cm³ to m³ (÷ 10⁶) and kPa to Pa for pV = nRT, °C to K (+ 273) for anything with temperature in it, J to kJ for enthalpy changes.

Spelling and conventions are part of the language: sulfur is spelled with an f throughout, the decimal marker is a dot on the line, and the traditional names sulfite, nitrite, sulfurous acid and nitrous acid are used.

🔬Practical work is not optional preparation

The syllabus states that learners should spend at least 20% of their course time doing practical work individually or in small groups, and that this excludes time spent watching demonstrations. Paper 3 is a real laboratory test — you will titrate, time reactions, measure temperature changes and identify ions from their reactions — and it rewards speed and accuracy that only practice builds.

Two pages here cover the practical papers directly, and there is one on the syllabus’s data section — the constants and tables the papers draw on — which includes the values you need for this page’s calculations.