How to get an A* in A-Level Chemistry
A-Level Chemistry is the subject where small gaps compound fastest. Physical chemistry feeds into organic, organic feeds into analysis, and Paper 3 expects you to combine all three with practical knowledge under timed pressure. Most students sitting at a high A in mocks are not far away from an A*, but the route there is technical rather than effort-based.
This guide is for students who already know most of the content and want to push from A to A*. It covers the exact threshold, the topics that consistently separate top-band students from the rest, the mechanisms that need to be airtight, and a six-month revision plan that mirrors how the AQA papers actually test you.
If you are reading this in Year 12, the same principles apply. Start early, drill mechanisms until they are automatic, and build the habit of writing full method-mark working on every calculation.
Roughly
~10%
of A-Level Chemistry students achieve an A* each year in England, based on recent JCQ summer series data. Chemistry has a slightly higher A* rate than Biology, partly because so many students take it as a stepping stone to medicine and the cohort is academically strong.
What an A* actually requires
AQA A-Level Chemistry (7405) is graded on the combined total of three papers. The A* boundary has typically landed around 79 to 83 percent of the total raw marks in recent years, roughly 237 to 250 marks out of 300, with 2023 the toughest at 250/300 (83 percent), 2024 at 239/300 (80 percent) and 2022 at 237/300 (79 percent).
The boundary is not split by paper. A weak Paper 2 can be balanced by a strong Paper 3, provided the overall total reaches the threshold. That gives you flexibility, but a single weak topic running across all three papers can pull the total below the line.
A* is awarded on the overall raw mark total. There is no requirement to score a specific percentage on any one paper.
The A-Level Chemistry exam structure
The AQA 7405 specification is examined through three two-hour papers sat at the end of Year 13. Each paper has its own content focus, and Paper 3 is synoptic, drawing across all the content plus practical and analytical questions.
| Paper | Duration | Marks | Content focus |
|---|---|---|---|
| Paper 1 | 2 hours | 105 marks | Physical chemistry topics 1-4, 7, 10 and 11. Inorganic chemistry topics 8 and 9. Short and long-answer questions. |
| Paper 2 | 2 hours | 105 marks | Physical chemistry topics 2, 3, 5, 6 and 12. Organic chemistry topics 13-19. Short and long-answer questions. |
| Paper 3 | 2 hours | 90 marks | Any content from the specification, plus 40 marks on practical techniques and data analysis. Includes 30 multiple-choice marks across all topics. |
Paper 3 is where the A* is often won or lost. The practical questions test the twelve required practicals, including procedure, sources of error, and interpretation of unexpected results. The multiple-choice section is high-stakes because there is no partial credit, and many students rush these 30 marks at the end of a long paper.
Across all three papers, around 20 percent of marks reward maths skills: Mole calculations, percentage yield, atom economy, equilibrium expressions, pH and buffer calculations, rate equations, and the use of the Arrhenius equation. Maths fluency is non-negotiable at A*.
The topics that always come up at A*
Certain topics appear in every paper and consistently separate A* students from A students. They tend to be the topics where the content is dense, the language must be precise, or the underlying maths trips people up.
| Topic | Why it separates A from A* |
|---|---|
| Organic mechanisms (nucleophilic substitution, electrophilic addition, free radical substitution) | Curly arrows must start and end in the right place. Lone pairs, partial charges, and intermediates need to be drawn precisely or marks are lost. |
| Equilibrium and Kc / Kp calculations | Requires setting up an ICE table correctly, identifying the correct concentrations or partial pressures, and managing units carefully. |
| Acid-base equilibria and buffers | pH calculations for weak acids, buffers, and titration curves are core A* content. Students often mix up Ka, Kw, and Kb. |
| Born-Haber cycles and enthalpy of solution | Requires confident use of Hess's law and accurate sign conventions. A single sign error throws the whole answer. |
| Electrode potentials and feasibility | Calculating E cell, predicting feasibility, and applying it to real systems like fuel cells and electrochemical series questions. |
| Transition metal chemistry | Colour changes, complex ions, and ligand substitution. Students struggle with the language of bidentate, chelate effect, and oxidation state changes. |
| NMR and IR spectroscopy | Combining proton NMR, carbon NMR, and IR data to identify unknown structures. Pattern recognition matters as much as chemistry knowledge. |
| Rate equations and rate-determining step | Deriving the rate equation from data, identifying orders, and linking the rate equation back to a proposed mechanism. |
Exam technique that separates A from A*
Command word discipline matters in Chemistry just as much as in Biology, but the technique gap is broader. Three specific habits separate A* answers from A answers, and all three need to be drilled until they are automatic.
First, show every step of every calculation. Method marks are the difference between dropping one mark and dropping three. Write the formula, substitute values, give units, and quote your final answer to the correct number of significant figures. The mark scheme almost always rewards each of these as separate marks.
Second, draw mechanisms with full precision. Every curly arrow must start at a bond or a lone pair and end at the atom or position where the electrons go. Show the lone pairs on the nucleophile. Draw the intermediate, including any charges. Examiner reports flag sloppy curly arrows as one of the most common reasons strong students lose marks.
Third, link your answers explicitly to the data given. If a question gives you a graph, a spectrum, or a set of values, your answer must reference them. "Because the rate doubles when the concentration doubles, the order is one" scores. "Because it is first order" does not. The link to the data is the mark.
On the multiple-choice section in Paper 3, do not rush. The questions are deliberately designed with plausible distractors, and a single careless tick can cost you a full mark you would have scored with ten extra seconds of thought.
A common mistake A-Level Chemistry students make is treating mechanisms as memorisation rather than logic. Examiners are not just checking whether you have learned the steps. They are checking whether you understand which atoms have lone pairs, which bonds are polar, and which intermediates can plausibly form. Generic curly arrows that do not start or end at the right place fail at A*.
How to revise for an A*
Top-band Chemistry revision rests on four pillars. Each pillar targets a different type of mark, and skipping any of them leaves a predictable gap in your final score.
Active recall is the foundation. Close your notes and write the trends, the equations, and the mechanisms from memory. For organic chemistry, draw the full reaction scheme for each functional group transformation without looking. For physical chemistry, write the key equations and what each symbol means before doing any problem set.
Calculation drilling is the second pillar. Mole and equilibrium calculations need to be automatic. Work through every type of calculation in the specification – percentage yield, atom economy, Kc, Kp, Ka, pH, buffer pH, rate constants, Arrhenius, enthalpy from Hess cycles, entropy and free energy. Aim for fluency rather than understanding alone.
Past papers are the third pillar. Work through every available paper for the current specification under timed conditions. Mark with the mark scheme open, and split your mistakes into content gaps, calculation slips, and command-word errors. Each needs a different fix.
Mark schemes and examiner reports are the fourth pillar. The examiner report flags exactly where the previous cohort lost marks. Read at least two years of reports for every paper and pay particular attention to recurring criticisms about precision in mechanisms and units.
A 6-month plan to A*
Six months gives you enough time to consolidate, target weaknesses, and build exam stamina. Adjust the start date based on when you are reading this, but the shape of the plan does not change.
Months 1-2 (November to December): Content consolidation. Work through every topic with active recall. Build a personal reaction map covering every functional group transformation in organic chemistry. Drill mole and equilibrium calculations every week. Do one full past paper at the end of December to set a baseline.
Months 3-4 (January to February): Past paper start and weakness targeting. Begin topic-by-topic past paper questions on your weakest areas. Use mark schemes after every question. Practise drawing mechanisms by hand until you can produce them without reference. Add at least one calculation drill per day.
Month 5 (March): Timed full papers. Move from topic-by-topic practice to full timed papers. Aim for one full paper per week minimum, with a deeper focus on Paper 3 because it has the broadest content and the multiple-choice section. Review every mistake.
Month 6 (April to May): Refinement and exam technique. Stop introducing new material. Drill the topics where you keep losing marks. Re-do past paper mechanisms and calculations until they are automatic. Sit at least one full mock weekend in the final fortnight to build endurance.
Your A* checklist
Work through this checklist across your final term to make sure no area is left behind.
- Active recall on every specification point – use blurting for organic reaction schemes
- All 12 required practicals revised, including techniques, sources of error, and typical mark schemes
- At least 8 full past papers completed under timed conditions, with full mistake reviews
- Read examiner reports for every paper from the last three years
- Drill every named mechanism by hand until curly arrows are precise
- Drill mole, equilibrium, pH, buffer, rate, and Born-Haber calculations until automatic
- Practise the multiple-choice section under time pressure – do not rush it on the day
- Build a personal mistake log and revisit it weekly
