Cambridge A-Level Chemistry 9701: Command words and keywords

Cambridge International A-level Chemistry (9701) uses the standard Cambridge command words. Mark schemes apply science-specific principles: keywords must be used correctly in context; spellings must allow clear separation from other terms. A-level expects more depth and application to unfamiliar contexts.

Command words in Chemistry 9701

Command word	What to do	Common mistake
State	Short answer	Overwriting
Define	Precise meaning	Vague
Describe	What happens; no “why”	Adding explanation
Explain	Why/how; use “because”	Only describing
Suggest	Apply to new context	Textbook recall
Calculate	Show working; units; sig figs	Wrong units
Write	Balanced equation; state symbols	Unbalanced
Draw	Displayed formula; correct structure	Wrong bonds
Predict	What will happen	Unsupported
Compare	Similarities and differences	Listing separately
Evaluate	Judge; conclude with evidence	No conclusion
Deduce	Work out from information	Guess

Keywords examiners look for

Structure and bonding

Term	Use correctly	Avoid
Ionic bond	Electrostatic attraction between ions	”Shared electrons”
Covalent bond	Shared pair of electrons	”Transfer” for covalent
Metallic bond	Delocalised electrons	Covalent
d-orbital	For transition metals	”Orbital”
Hybridisation	sp, sp², sp³	”Mixing”
Polar	Unequal electron distribution	”Charged”
Intermolecular forces	Between molecules	Intramolecular
Hydrogen bonding	H with N, O or F	”Strong bond”
London forces	Temporary dipoles	Van der Waals (broader)

Organic chemistry

Term	Use correctly	Avoid
Electrophile	Electron-deficient; accepts pair	Nucleophile
Nucleophile	Electron-rich; donates pair	Electrophile
Nucleophilic substitution	Nucleophile replaces leaving group	”Substitution”
Electrophilic addition	Electrophile adds to double bond	”Addition”
Free radical	Species with unpaired electron	Ion
Activation energy	Minimum energy for reaction	”Energy to start”
Catalyst	Speeds up; unchanged	”Used up”
Equilibrium	Forward and reverse rates equal	”Balance”
Le Chatelier	System shifts to oppose change	”Balance”

Energetics and kinetics

Term	Use correctly	Avoid
Enthalpy change	ΔH; heat at constant pressure	”Heat”
Exothermic	ΔH negative	”Hot”
Endothermic	ΔH positive	”Cold”
Activation energy	Ea; minimum for reaction	”Energy”
Rate-determining step	Slowest step	”Slow step”
Order	Exponent in rate equation	”Speed”
Half-life	Time for concentration to halve	”Half the time”

Acids and redox

Term	Use correctly	Avoid
Oxidation	Loss of electrons	Gain of oxygen only
Reduction	Gain of electrons	Loss of oxygen only
Oxidising agent	Accepts electrons	Reduces
Reducing agent	Donates electrons	Oxidises
Brønsted-Lowry acid	H⁺ donor	”Sour”
Brønsted-Lowry base	H⁺ acceptor	”Bitter”
Conjugate pair	Acid and its conjugate base	”Pair”
Buffer	Resists pH change	”Neutraliser”
Buffer region	Where pH changes slowly	”Flat”

Tips for Chemistry 9701

1. Learn pairs—electrophile/nucleophile, oxidation/reduction
2. Use keywords in context—correct scientific use
3. Show working in calculations; include units
4. State symbols in equations when required
5. Suggest—apply to the specific scenario
6. Past papers + mark schemes show acceptable wording

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Based on Cambridge International A-level Chemistry 9701 syllabus. Check the latest syllabus for your exam series.