How to revise organic chemistry (without it all falling out of your head)

Why does organic chemistry feel so different to revise from the rest of the course?

I get asked this a lot, and I think the answer is pretty simple: there’s just more to remember. In most physical chemistry topics, once you understand the idea and can use the equations, you can work a lot out in the exam. Organic isn’t like that. For every reaction you need the reagents, the conditions, the type of reaction, the mechanism, the products – and then you have to link it all together into multi-step pathways. Understanding it helps, but you can’t reason your way to ‘NaOH, aqueous, reflux’ if you haven’t learned it.

So organic needs a different approach, and that approach is regular retrieval practice.

Common revision mistakes

Before we get to what works, here are the mistakes I see most often:

• Too little, too late. Leaving organic until the last few weeks and hoping it’ll ‘go in’ through past papers.
• Too much, too soon. Diving straight into full past papers before you can recall the basics, then getting demoralised when it doesn’t go well.
• Revising one topic at a time. Learning alkenes, then haloalkanes, then alcohols as separate boxes. Exam questions don’t respect those boxes – they want you to link reactions together.
• Taking mental shortcuts. Reading over your notes, nodding along and thinking ‘yes, I know that’. Recognising something isn’t the same as being able to recall it.

What is retrieval practice?

Retrieval practice just means bringing information back to mind without looking at it. It’s a different skill from answering practice questions, which test whether you can apply what you know. You need both, but retrieval comes first – there’s no point applying knowledge you can’t pull out of your head.

Retrieval practice works best when it’s:

• Randomised – mix up the reactions and functional groups rather than going through them in order
• Little and often – ten minutes most days beats a three-hour session once a week
• Low stakes – it’s practice, not a test with a grade attached

Low stakes doesn’t mean easy, though. You have to test yourself properly, which means writing it down on a mini whiteboard or scrap paper, not just ‘saying it in your head’. And getting it wrong is part of the process. When you can’t remember something, do something about it: check it, make a note, and come back to it later. That’s where the learning happens.

What should you be recalling?

This is where a lot of students get stuck. They know they should test themselves, but they don’t know what to ask. Here are some prompts that work well.

For a reaction pathway:

• Draw the functional groups
• What are the reagents?
• What are the conditions?
• What type of reaction is it?
• What’s the mechanism?
• Can you join it into a multi-step route?

For a functional group:

• How do you name or classify it?
• What are its physical properties, and how do they link to intermolecular forces?
• What types of reactions does it do – with which reagents and conditions?
• Can you write the equations and draw the mechanisms?
• Are there any isomers or alternative products?
• How do you make this functional group in the first place?
• What chemical tests are there for it?
• How does it show up in IR, NMR and mass spectrometry?

If you can go through that list for every functional group without looking at your notes, you’re in a really strong position.

Where past papers fit in

Past paper questions are important, but they’re the second step, not the first. Once your recall is solid, start with mixed organic questions under timed conditions rather than jumping straight to full papers. That way you’re practising the skill of applying and linking your knowledge without using up papers you’ll want later for full mocks.

Planning your revision

As the exams get closer, the balance of what you’re doing should shift. Roughly:

• Early on: 40% consolidating your understanding, 40% retrieval practice, 20% practice questions
• Mid-way: 60% retrieval practice, 40% practice questions
• Final weeks: 40% practice questions, 60% past papers

Notice that retrieval practice doesn’t disappear – it just makes room for more exam practice as you go. And spacing it out matters. Coming back to a reaction a few days later, then a week later, then a few weeks later, is far more effective than revising it five times in one evening.

Use a weekly and daily timetable, and be specific about what you’ll do in each slot (‘nucleophilic substitution – reagents and mechanism’) rather than ‘revise organic’. Be realistic, though. An over-ambitious plan that falls apart by Wednesday isn’t helping anyone.

A free resource to get you started

To help with this, I’ve made a set of organic reaction summary sheets covering the first five reactions at A Level: electrophilic addition, nucleophilic substitution, free radical substitution, nucleophilic addition and oxidation.

Each sheet has six squares: example equations, which functional groups, mechanism, important notes, reagents and conditions, and products. They’re designed to be used as retrieval prompts, not just read. Cover the six squares with post-it notes, then use the headings to try and recall everything you can for that reaction. Peel off the post-its to check, note what you missed, and come back to it in a few days.

If you’d like more support with organic chemistry (or anything else in A Level chemistry), feel free to email me – I’m always happy to answer questions.