OCR · A Level · H432
Chemistry — Keywords & Key Terms — Definitions Glossary (2026)
OCR A Level Chemistry A (H432)
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 A Level Chemistry (H432)
OCR A Level Chemistry (H432)
OCR A Level Chemistry A (H432)
OCR Chemistry A (H432) modules: development of practical skills, foundations in chemistry, periodic table and energy, core organic chemistry, physical chemistry and transition elements, and organic chemistry and analysis — examined across Papers 1–3.
Mark schemes: OCR demands precise IUPAC names, state symbols in equations and correct units (kJ mol⁻¹, mol dm⁻³). ΔH signs must match exothermic/endothermic context; equilibrium expressions raise concentrations to stoichiometric powers. Mechanisms require curly arrows from a bond or lone pair to an electrophilic centre, with δ+/δ− shown where relevant.
Active recall: 0 / 21 terms ticked
| Recalled | Topic | Level | Keyword | Definition |
|---|---|---|---|---|
| Atoms, moles & gases | Essential | Mole | Amount of substance containing 6.02 × 10²³ specified entities (Avogadro's constant). | |
| Atoms, moles & gases | Core | Mass–mole relation | n = m/M, where m is mass in g and M is molar mass in g mol⁻¹. | |
| Atoms, moles & gases | Core | Concentration | n = cV, where c is in mol dm⁻³ and V in dm³. | |
| Atoms, moles & gases | Core | Ideal gas equation | pV = nRT with R = 8.31 J K⁻¹ mol⁻¹ and SI units throughout. | |
| Atoms, moles & gases | Advanced | Empirical vs molecular formula | Empirical is the simplest whole-number ratio; molecular is the actual number of atoms per molecule. | |
| Energetics & thermodynamics | Core | Standard enthalpy change | Heat exchanged at constant pressure under standard conditions (100 kPa, 298 K). | |
| Energetics & thermodynamics | Core | Hess's law | ΔH = Σ ΔHf(products) − Σ ΔHf(reactants); enthalpy change is route-independent. | |
| Energetics & thermodynamics | Core | Lattice enthalpy | Enthalpy change forming one mole of ionic lattice from gaseous ions; found via Born–Haber cycle. | |
| Energetics & thermodynamics | Core | Entropy ΔS | Measure of disorder; positive when disorder increases (e.g. solid → gas). | |
| Energetics & thermodynamics | Advanced | Gibbs free energy | ΔG = ΔH − TΔS; reaction is feasible when ΔG < 0 at the stated temperature. | |
| Kinetics & equilibria | Core | Rate equation | Experimentally determined: rate = k[A]^m[B]^n with overall order m + n. | |
| Kinetics & equilibria | Core | Arrhenius equation | k = A e^(−Ea/RT); plot of ln k against 1/T has gradient −Ea/R. | |
| Kinetics & equilibria | Core | Equilibrium constants Kc and Kp | Kc uses equilibrium concentrations; Kp uses partial pressures of gases. | |
| Kinetics & equilibria | Core | Le Chatelier's principle | Equilibrium position shifts to partially oppose any imposed change. | |
| Kinetics & equilibria | Core | pH and Ka | pH = −log[H⁺]; Ka = [H⁺][A⁻]/[HA] for a weak acid dissociation. | |
| Kinetics & equilibria | Advanced | Henderson–Hasselbalch | Buffer pH = pKa + log([A⁻]/[HA]); resists pH change on small additions of acid or base. | |
| Organic chemistry & analysis | Core | Nucleophilic substitution | Nucleophile replaces a leaving group at a saturated carbon via SN1 or SN2. | |
| Organic chemistry & analysis | Core | Electrophilic addition | Alkenes attacked by an electrophile across the C=C double bond. | |
| Organic chemistry & analysis | Core | ¹H and ¹³C NMR | Spectra showing chemical environments of hydrogen and carbon atoms via chemical shift. | |
| Organic chemistry & analysis | Core | Infrared spectroscopy | Identifies functional groups from characteristic absorption wavenumbers. | |
| Organic chemistry & analysis | Advanced | Mass spectrometry | Molecular ion peak gives Mr; fragmentation pattern aids structure elucidation. |
Pair this with our revision checklists, formula sheets hub and past paper finder.
Chemistry (H432) — Keywords & Key Terms FAQ
- What is on this OCR A Level Chemistry keywords and key terms list?
- It is a topic-organised glossary of important chemistry terms with short, exam-style definitions aligned to OCR A Level Chemistry A (H432) (H432). 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 A Level Chemistry (H432) 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 H432 specification?
- Topic groupings and wording follow OCR A Level Chemistry A (H432) for OCR A Level. 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 A Level, separate from longer notes or topic trackers.