OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P1.1 The Particle Model Exam Questions
Free OCR GCSE Physics A exam questions for P1.1 The Particle Model, with a mark scheme for every pack. Covers the particle model of Matter, density, the structure of the atom and how models of the atom developed over time.
P1.1 The Particle Model exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P1.1 The Particle Model
P1.1 opens the P1 Matter chapter of OCR Gateway Physics A. It uses the simple particle model to explain the differences between solids, liquids and gases and why their densities differ. You learn to calculate density and describe how to measure it for regular and irregular objects. The topic also covers the structure of the atom, its size compared with the nucleus, and how the model of the atom changed from Dalton through Thomson and Rutherford to Bohr as new evidence emerged. It leads into P1.2 on changes of state and P6 on radioactivity. Examiners like density calculations with unit conversions and questions on why scientific models change.
What you need to know
- Particle model Solids have particles closely packed in a regular arrangement that vibrate about fixed positions; liquids are close together but random and able to move past each other; gases are far apart and move quickly in random directions.
- Density Density = mass / volume, measured in kg/m^3 or g/cm^3. Gases have much lower density because their particles are far apart.
- Measuring density Regular objects: measure dimensions with a ruler and mass with a balance. Irregular objects: find volume by displacement in a eureka can or measuring cylinder.
- Atomic structure Atoms contain a small positive nucleus of protons and neutrons with electrons around it. Atoms have radius of about 1 x 10^-10 m and the nucleus is about 100 000 times smaller.
- Models of the atom Dalton described solid spheres; Thomson discovered the electron and proposed the plum pudding model; Rutherford's alpha scattering showed a small dense positive nucleus; Bohr placed electrons in fixed energy levels.
- Limits of the model The particle model does not show the forces between particles, their actual size or motion, so it is a simplification.
Common mistakes in P1.1 The Particle Model
- Saying particles in a solid do not move. They vibrate about fixed positions.
- Saying particles expand when heated. The spacing between them changes, not the particles themselves.
- Mixing up g/cm^3 and kg/m^3. 1 g/cm^3 = 1000 kg/m^3.
- Saying Rutherford's experiment showed electrons orbit in shells. It showed a small, dense, positive nucleus; energy levels came from Bohr.
- Forgetting that most alpha particles passed straight through the foil, which showed most of the atom is empty space.
Try three P1.1 The Particle Model exam-style questions
1. A block measures 2.0 cm x 3.0 cm x 5.0 cm and has a mass of 81 g. Calculate its density. (3 marks)
Show the mark scheme answer
Volume = 2.0 x 3.0 x 5.0 = 30 cm^3; density = mass / volume = 81 / 30; = 2.7 g/cm^3.
2. Calculate the mass of 0.25 m^3 of steel of density 8000 kg/m^3. (2 marks)
Show the mark scheme answer
Mass = density x volume = 8000 x 0.25; = 2000 kg.
3. Explain how the results of the alpha particle scattering experiment changed the model of the atom. (4 marks)
Show the mark scheme answer
Most alpha particles passed straight through, so most of the atom is empty space; a few were deflected, so the centre is positively charged; a very small number bounced back, so mass and charge are concentrated in a tiny nucleus; this replaced the plum pudding model.
P1.1 The Particle Model FAQs
What does OCR GCSE Physics A (Gateway Science) P1.1 The Particle Model cover?
It covers the particle model of solids, liquids and gases, density and how to measure it, atomic structure and the development of the model of the atom.
Which paper is P1.1 examined on?
Topics P1 to P4 are assessed on Paper 1 (Foundation) or Paper 3 (Higher), alongside practical skills.
How do I measure the density of an irregular object?
Measure its mass on a balance, lower it into a eureka can or measuring cylinder of water to find the volume displaced, then divide mass by volume.
