OCR · GCSE · J248
Chemistry — Keywords & Key Terms — Definitions Glossary (2026)
OCR GCSE (9-1) Gateway Science Chemistry A (J248)
Topic-by-topic keywords, key terms and definitions for precise exam language—separate from our revision checklists (topic coverage) and formula sheets (equations).
Keywords & Key Terms — definitions
Examiner-style keywords and definitions organised by syllabus topic. Terms are tagged Essential (start here), Core (typical exam standard), and Advanced for harder distinctions — tick each row when you can recall it. Your progress is saved in this browser for this list.
OCR GCSE Chemistry (J248)
OCR GCSE Chemistry (J248)
OCR GCSE (9-1) Gateway Science Chemistry A (J248)
Topics follow OCR Gateway Science Chemistry A (J248): particles, atoms, chemical reactions, energy changes, rates and organic chemistry, across Foundation and Higher tiers.
Mark schemes: OCR examiners require precise chemical vocabulary, balanced symbol equations with state symbols where appropriate, and clear units in mole and concentration calculations.
Active recall: 0 / 19 terms ticked
| Recalled | Topic | Level | Keyword | Definition |
|---|---|---|---|---|
| 1. Particles & atoms | Essential | Atom | Smallest particle of an element that retains its chemical identity. | |
| 1. Particles & atoms | Core | Mole | Amount of substance: n = mass / Mr; one mole contains Avogadro's number of particles. | |
| 1. Particles & atoms | Core | Avogadro constant | 6.02 × 10²³ particles per mole. | |
| 1. Particles & atoms | Core | Concentration | Amount of solute per unit volume of solution: C = n/V (mol/dm³). | |
| 1. Particles & atoms | Advanced | Relative formula mass (Mr) | Sum of relative atomic masses of all atoms in a chemical formula. | |
| 2. Chemical reactions | Essential | Neutralisation | Acid + base reaction producing a salt and water. | |
| 2. Chemical reactions | Core | Percentage yield | (Actual yield ÷ theoretical yield) × 100%. | |
| 2. Chemical reactions | Core | Atom economy | (Mr of useful products ÷ Mr of all reactants) × 100%, a measure of efficiency. | |
| 2. Chemical reactions | Core | Electrolysis | Decomposition of an ionic compound (molten or in solution) using electrical energy. | |
| 2. Chemical reactions | Advanced | pH equation | pH = −log[H⁺]; quantifies hydrogen ion concentration. | |
| 3. Energy changes | Essential | Exothermic | A reaction that transfers thermal energy to the surroundings, raising temperature. | |
| 3. Energy changes | Essential | Endothermic | A reaction that takes in thermal energy from the surroundings, lowering temperature. | |
| 3. Energy changes | Core | Activation energy | Minimum energy required for colliding particles to react successfully. | |
| 3. Energy changes | Advanced | Bond energy calculation | ΔH = energy to break reactant bonds − energy released forming product bonds. | |
| 4. Organic chemistry | Essential | Hydrocarbon | Compound containing only carbon and hydrogen atoms. | |
| 4. Organic chemistry | Core | Alkane | Saturated hydrocarbon with general formula CnH2n+2; only single C–C bonds. | |
| 4. Organic chemistry | Core | Alkene | Unsaturated hydrocarbon with general formula CnH2n; contains a C=C bond. | |
| 4. Organic chemistry | Core | Cracking | Thermal decomposition of long-chain alkanes into smaller, more useful molecules. | |
| 4. Organic chemistry | Advanced | Combustion | Reaction with oxygen; complete combustion of hydrocarbons gives CO₂ and H₂O. |
Pair this with our revision checklists, formula sheets hub and past paper finder.
Chemistry (J248) — Keywords & Key Terms FAQ
- What is on this OCR GCSE Chemistry keywords and key terms list?
- It is a topic-organised glossary of important chemistry terms with short, exam-style definitions aligned to OCR GCSE (9-1) Gateway Science Chemistry A (J248) (J248). It is designed for “define”, “state”, “outline” and “explain” questions where precise vocabulary earns marks.
- How should I use this Chemistry glossary alongside past papers?
- Tick terms when you can recall them without reading the answer, then check your wording against mark schemes. Pair vocabulary practice with past papers for GCSE Chemistry (J248) so you apply terms in context.
- Is this the same as a revision checklist or a formula sheet?
- No. Revision checklists help you track which syllabus topics you have covered and your confidence—separate pages on Tutopiya. Formula sheets summarise equations and quantitative relationships. This page is only a definitions and key-terms glossary for Chemistry. Quantitative relationships belong on formula sheets; this list emphasises language and concepts.
- Can I download this Chemistry keywords and key terms list for free?
- Yes. After a quick free sign-up you can download a UTF-8 CSV (opens in Excel or Google Sheets) or open a print-friendly page and save as PDF. Browsing the list on the page is free.
- Is this Chemistry list aligned to the J248 specification?
- Topic groupings and wording follow OCR GCSE (9-1) Gateway Science Chemistry A (J248) for OCR GCSE. Always confirm final learning objectives and any regional options in your official specification and recent examiner reports for your exam session.
- Why focus on definitions instead of full notes?
- Mark schemes reward correct technical terms and clear links between ideas. A compact glossary lets you drill the exact language examiners expect for Chemistry at GCSE, separate from longer notes or topic trackers.