OCR GCSE Chemistry A (Gateway)
OCR GCSE Chemistry A C1.1 The Particle Model Exam Questions
Free OCR GCSE Chemistry A exam questions for C1.1 The Particle Model, with a mark scheme for every pack. Covers states of matter, particle arrangement and movement, changes of state, physical and chemical changes, and limitations of the model.
C1.1 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 Chemistry A C1.1 The Particle Model
C1.1 opens the OCR Gateway Chemistry A course with the particle model, the idea that all matter is made of tiny particles whose arrangement and movement explain the properties of solids, liquids and gases. It is part of Topic C1 Particles, assessed in Paper 1 (Foundation) or Paper 3 (Higher). This topic underpins bonding and structure in C2, energy changes in C3 and rates of reaction in C5. Examiners tend to test descriptions of particle arrangement, explanations of melting and boiling in terms of energy and forces, the difference between physical and chemical changes, and the limitations of representing particles as small solid spheres.
What you need to know
- Three states of matter In solids, particles are closely packed in a regular arrangement and vibrate about fixed positions. In liquids, particles are close together but randomly arranged and can move past each other. In gases, particles are far apart, randomly arranged and move quickly in all directions.
- Changes of state Melting, boiling, condensing, freezing and sublimation are changes of state. During melting or boiling, energy is used to overcome the forces of attraction between particles, so the temperature stays constant until the change is complete.
- Predicting states A substance is solid below its melting point, liquid between its melting and boiling points, and gas above its boiling point. The stronger the forces between particles, the higher the melting and boiling points.
- Physical and chemical changes Changes of state are physical changes: no new substances form and they are easily reversed. Chemical changes form new substances and are usually hard to reverse.
- Limitations of the model The simple model shows particles as solid, inelastic spheres with no forces between them. In reality particles are not solid spheres, there are forces of attraction, and the diagrams do not show relative particle size or spacing accurately.
Common mistakes in C1.1 The Particle Model
- Saying particles in a solid do not move. They vibrate about fixed positions.
- Stating that particles expand when heated. The particles do not get bigger; they move faster and further apart.
- Writing that bonds within molecules break when a simple molecular substance boils. Only the weak intermolecular forces are overcome.
- Describing particles in a liquid as far apart. Liquid particles are close together, almost as close as in a solid.
- Assuming temperature rises during a change of state. The temperature stays constant while energy breaks the forces between particles.
Try three C1.1 The Particle Model exam-style questions
1. Bromine melts at -7 degrees C and boils at 59 degrees C. State the physical state of bromine at 20 degrees C and explain your answer. (2 marks)
Show the mark scheme answer
Liquid; 20 degrees C is above its melting point but below its boiling point.
2. Describe the changes in arrangement and movement of particles when a solid melts. (3 marks)
Show the mark scheme answer
Particles gain energy and vibrate more; forces of attraction between particles are overcome (weakened); particles change from a regular fixed arrangement to a random arrangement where they can move past each other.
3. Give two limitations of the simple particle model. (2 marks)
Show the mark scheme answer
Particles are shown as solid, inelastic spheres; forces between particles are not shown; particles are not actually spherical; diagrams do not show the true spacing or size. Any two.
C1.1 The Particle Model FAQs
What does OCR GCSE Chemistry A C1.1 The particle model cover?
It covers the arrangement and movement of particles in solids, liquids and gases, changes of state, physical and chemical changes, and the limitations of the particle model.
Which paper is C1.1 examined in?
Topic C1 is assessed in Paper 1 (Foundation) or Paper 3 (Higher), and the ideas are assumed in Paper 2 and Paper 4.
How do I explain melting and boiling points in C1.1?
Link the temperature to the energy needed to overcome forces of attraction between particles: stronger forces need more energy, so the melting or boiling point is higher.
