How to study chemistry: what to memorize and what to practice

To study chemistry, split the course into two kinds of work: things you should recall instantly, such as element symbols, common ion charges and naming rules, and things you need to solve, such as balancing equations or stoichiometry. Flashcards handle the first group and the decisions behind the second. Calculations need full practice problems.

Mixing the two in one list is what makes the subject feel heavy. If you memorize the solution to one specific problem, you will not know where to start once the numbers change. If you work out every symbol or charge while solving, you spend attention on facts that should come automatically. Keeping them apart lets you choose the right activity for each session.

Before you make cards, read the course outline and mark what you are expected to know from memory. Not everything in the syllabus is the same kind of knowledge, and a short, well-chosen list is easier to review than a deck built from the whole textbook.

In problem solving, what people forget is rarely the arithmetic. It is the first step. The most useful chemistry cards ask what to do and why: “You have grams of a reactant and need grams of product. What conversion comes first?” Answer: convert grams to moles with the molar mass, because a balanced equation relates moles, not grams.

Another useful card contrasts similar cases: “When do you need to find the limiting reactant?” When the problem gives amounts for two or more reactants and does not say one is in excess. These questions do not replace practice problems, but they help you recognize the route when a new problem appears instead of hunting for an identical one in your notes.

Our own problem: how many grams of water form when 8 g of hydrogen (H₂) react with excess oxygen? The balanced equation is 2 H₂ + O₂ → 2 H₂O. Using rounded atomic masses (H = 1, O = 16), the molar mass of H₂ is 2 g/mol and that of water is 18 g/mol.

If you practice a whole chapter of identical problems, each exercise tells you the method before you read it. On the exam, problems arrive mixed. Rohrer and colleagues (2020) ran a trial with seventh-grade students comparing interleaved math practice with blocked practice, and the mixed-practice group scored higher on a later test. That study was about math, not chemistry or flashcards, but the logic carries over: choosing the method is a skill you need to practice.

Once you can solve each type on its own, build sheets that mix stoichiometry, concentration and gas law problems in random order. Before calculating, write one line naming the problem type and the first conversion. The example above gives you cards about that first step; the full calculation, with new numbers, belongs on the practice sheet.

Roediger and Karpicke (2006) found, using prose passages, that students who tested themselves remembered more a week later than students who restudied the same material. In chemistry, that means closing the book and writing out the ion table you are learning from memory, or explaining out loud why a reaction counts as neutralization, before you check.

A 45-minute session could look like this: ten minutes of flashcards, twenty-five minutes of mixed problems without looking at solutions, and ten minutes of correction. When you correct, note whether each error was conceptual, about units or arithmetic. If the same kind of error keeps showing up, write a card for that specific decision.

These mistakes show up again and again in chemistry notebooks, and most of them are easy to fix if you catch them early in the term.

In Lumia AI you can create a book for the course and split it into blocks or neurons by unit, for example naming, stoichiometry and solutions. You can write your decision cards by hand or generate a draft from your notes or a PDF; check every formula, charge and subscript, because one small error changes the answer.

For pairs such as ion and charge, a quiz with Match Pairs questions makes you tell similar options apart. During review, rate each card Again, Hard, Good or Easy and Lumia schedules the next review. Full problems stay on paper: Lumia does not check calculations you write by hand.