GCSE Physics: Particle Model — Deep Revision Workbook

Inside GCSE Physics: Particle Model — Deep Revision Workbook

calculate density and describe the particle model, work through changes of state, conservation of mass and internal energy, master specific heat capacity E = mcΔθ and specific latent heat E = mL, then explain heating curves and gas pressure including p₁V₁ = p₂V₂, before a full exam-style 6-mark question. About 45 minutes.

Learning objectives

• density and the particle model — the equation ρ = m/V, rearranging it for mass, the required practical with a displacement can, and the arrangement of particles in the three states;
• changes of state and internal energy — melting, freezing, boiling and condensing as physical changes with conserved mass, and internal energy as total kinetic plus potential energy;
• specific heat capacity and latent heat — E = mcΔθ and rearranging it for temperature change, and E = mL for latent heat of fusion and vaporisation;
• heating curves and gas pressure — the flat sections of heating graphs, pressure from particle collisions, and how pressure changes with temperature at constant volume;
• pressure and volume — the p₁V₁ = p₂V₂ relationship at constant temperature (Higher), and a full exam-style 6-mark question.

Activities in this book

1. Section 1 — Density & the Particle Model

   density = mass ÷ volume, ρ = m/V. Rearranged, mass = ρ × V. Keep units consistent (g with cm³, or kg with m³). For the required practical, measure the volume of a regular solid with a ruler, and of an irregular solid by lowering it into a displacement can and collecting the water it pushes out.

2. Section 2 — Changes of State & Internal Energy

   changes of state are physical changes: no new substance is made and the total mass is conserved. Internal energy is the total kinetic energy (how fast particles move) plus the potential energy (how the particles are arranged) of a system. Heating without a change of state raises the kinetic energy, so the temperature rises; during melting or boiling the temperature stays constant.

3. Section 3 — Specific Heat Capacity & Latent Heat

   to warm something up without a change of state, use E = mcΔθ (energy = mass × specific heat capacity × temperature change), and rearrange it as Δθ = E ÷ (mc). To change its state at constant temperature, use E = mL. Latent heat of fusion is for melting; latent heat of vaporisation is for boiling, and it is always the larger of the two.

4. Section 4 — Heating Curves & Gas Pressure

   on a heating graph, the sloping parts show the temperature rising, and the flat sections show a change of state, where energy breaks bonds between particles instead of raising the temperature. Gas particles collide with the container walls to make pressure; heating a fixed-volume gas raises the pressure. For a fixed mass at constant temperature, p₁V₁ = p₂V₂.

5. Section 5 — Extended Exam-Style 6-Marker

   a 6-mark question rewards clear, linked physics. Plan first: describe the particles at each stage, name each change of state, use internal energy and the difference between raising the temperature (kinetic energy) and changing state (latent heat), and explain the flat sections of the heating graph. Where you can, name an equation or give a number. Write in full sentences with the correct key terms.

Suggestions for teaching

• Start with the density equation. Cover ρ = m/V and insist on consistent units (g with cm³, or kg with m³) before dividing, then show it rearranged for mass.
• Draw the three states. Have learners sketch particle diagrams for solids, liquids and gases and link each to density and compressibility.
• Separate the two equations. Use E = mcΔθ only when the temperature changes and E = mL only during a change of state — the commonest exam slip is mixing them up.
• Model a heating graph. Point out the flat sections during melting and boiling, and explain the energy is breaking bonds (latent heat), not raising temperature.
• Use particle collisions for pressure. Relate faster particles and more frequent, harder collisions to higher pressure, then introduce p₁V₁ = p₂V₂ for the Higher tier.