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.
Core learning content
Start with this short teaching sequence for Internal Energy and Heating Curves. Read the model, use the visual, then test your recall before moving into examples and exam practice.
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.
Choose a relationship because of the physical change in the question, not because it is familiar. Density: ρ = m ÷ V (kg/m³, kg, m³). Specific heat capacity: E = mcΔθ (J, kg, J/(kg °C), °C). Pressure: p = F ÷ A (Pa, N, m²). Keep the unit next to each value while you substitute.
Describe both particle motion and separation, and use E = mcΔθ only for a temperature change rather than a state change. Before writing, underline the command word and identify the information that matters. Keep a calculation as equation, substitution and answer with unit; keep an explanation as a linked chain using because, so or therefore. Finish by checking that the final sentence answers the exact context in the question and that the number, direction or conclusion agrees with the evidence given.
Retrieval practice
Answer without looking back first. The feedback explains the model, so a wrong answer still helps you learn.
Mini quiz 1
Mini quiz 2
Mini quiz 3
Try it
What does a flat section of a heating curve tell you about the particles?
What to notice: the readout and written explanation remain available if you do not use the controls.
Worked examples
Cover the answer, attempt the method and then compare your physics language as well as the number.
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.
Misconception clinic
Each of these is tempting because it sounds almost right. Replace it with the precise physics before you meet it in a question.
Independent practice
Use the working space first. Reveal the guidance only after you have committed to an answer, then improve the exact part that would gain the next mark.
The total kinetic and potential energy of the particles in a system.
Temperature is rising, so average particle kinetic energy is increasing.
Energy separates particles/increases potential energy rather than average kinetic energy.
E = 2.0 × 4200 × 5.0 = 42 000 J.
Evaporation can occur at the surface below boiling point; boiling occurs throughout the liquid at its boiling point.
Particles have greater average kinetic energy and may be farther apart.
Questions pupils ask
Use a particle model to explain density, changes of state, internal energy and gas pressure. Keep particle spacing, particle motion and energy separate.
Read the snapshot, attempt the worked examples without looking, complete the mini quizzes and then use the practice questions to check your wording and method.
Next step
Physics sticks when you move between explanation, retrieval and application.