GCSE Physics resources
AQA GCSE Particle model of matter
Internal energy is the total kinetic and potential energy of the particles. Sloped sections of a heating curve show increasing average kinetic energy; flat sections show a change of state while separation changes.
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Internal energy is the total kinetic and potential energy of the particles. Sloped sections of a heating curve show increasing average kinetic energy; flat sections show a change of state while separation changes.
Before you revise
Choose an answer from memory. Your result tells you what to watch for in the guide.
Core revision guide
Internal Energy and Heating Curves questions become manageable when the central model, evidence and exam method are kept together. Read the explanation, test the misconception and then apply the idea without looking back.
Internal energy is the total kinetic and potential energy of the particles. Sloped sections of a heating curve show increasing average kinetic energy; flat sections show a change of state while separation changes.
Temperature measures average kinetic energy of particles. On the sloping parts of a heating curve, particles move faster. During melting or boiling, energy separates particles instead, increasing their potential energy while the temperature of a pure substance stays constant.
Specific heat capacity: E = mcΔθ (J, kg, J/(kg °C), °C). Choose each relationship from the physical change described, convert quantities into compatible units and keep the unit beside the final answer.
Misconception clinic
Read each belief, say what is wrong with it, then compare your correction.
Tempting idea: Using E = mcΔθ during a change of state.
Use instead: Internal energy is the total kinetic and potential energy of the particles. Sloped sections of a heating curve show increasing average kinetic energy; flat sections show a change of state while separation changes.
Tempting idea: Saying particles gain mass when heated.
Use instead: Temperature measures average kinetic energy of particles. On the sloping parts of a heating curve, particles move faster. During melting or boiling, energy separates particles instead, increasing their potential energy while the temperature of a pure substance stays constant.
Tempting idea: Saying temperature measures total internal energy.
Use instead: Describe both particle motion and separation, and use E = mcΔθ only for a temperature change rather than a state change.
Retrieval practice
Explore the relationship
Use the energy position to locate a point on the heating curve. The heating rate then determines the time taken to supply that energy.
What to notice: use the readout to describe how one variable changes when the other is controlled.
Worked examples
These examples expose the difference between a secure energy during heating and changes of state method and the common error “Using E = mcΔθ during a change of state.”.
E = 5400 J.
Energy increases particle potential energy by separating particles, so average kinetic energy and temperature stay constant.
Work is done on the gas, increasing its internal energy; particle kinetic energy and temperature can rise.
Exam precision
Do this: Describe both particle motion and separation, and use E = mcΔθ only for a temperature change rather than a state change.
Independent practice
Write an answer before opening the marking guidance. Then edit the exact phrase or step that would gain the next mark.
Marking guidance: 2 marks are available for relevant, linked physics points that match the model answer.
Model answer: The total kinetic and potential energy of the particles in a system.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: Temperature is rising, so average particle kinetic energy is increasing.
Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.
Model answer: Energy separates particles/increases potential energy rather than average kinetic energy.
Marking guidance: Award one mark for the correct relationship, one for a valid substitution and one for the final answer with its unit.
Model answer: E = 2.0 × 4200 × 5.0 = 42 000 J.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: Evaporation can occur at the surface below boiling point; boiling occurs throughout the liquid at its boiling point.
Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.
Model answer: Particles have greater average kinetic energy and may be farther apart.
Questions pupils ask
Internal energy is the total kinetic and potential energy of the particles. Sloped sections of a heating curve show increasing average kinetic energy; flat sections show a change of state while separation changes.
Using E = mcΔθ during a change of state. Temperature measures average kinetic energy of particles. On the sloping parts of a heating curve, particles move faster. During melting or boiling, energy separates particles instead, increasing their potential energy while the temperature of a pure substance stays constant.
Useful next steps