Year 7 - Science
Melting: particle model
Solid, liquid, gas states and changes of state
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers the properties of solids, liquids, and gases using the particle model, including gas pressure. It explains changes of state in terms of the particle model while developing skills in using appropriate techniques, apparatus, and materials in lab work.
Lesson Summary
You will learn to use the particle model to explain why substances have different melting points, and use a thermometer to measure melting points.
Key Notes
- In the solid state, forces of attraction between particles hold them in fixed positions.
- In the liquid state, particles are held together but have enough energy to break free to move around.
- The stronger the force of attraction between particles in a substance, the higher its melting point.
- Water freezes at 0ºC, room temperature is about 20ºC and body temperature is about 37ºC.
- The bulb of a thermometer is made of very thin glass and is delicate.
Vocabulary To Learn
- melting: Melting is when a substance changes from a solid state to a liquid state.
- melting point: The melting point of a substance is the temperature at which it changes from solid state to a liquid state.
- forces of attraction: Forces of attraction hold particles together.
- regular arrangement: In a solid state the particles are in a regular arrangement.
- random arrangement: In a liquid state the particles are in a random arrangement.
Common Mistakes To Avoid
- Particle spacing can be overemphasised at the expense of particle movement.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
In the solid state, forces of attraction between particles hold them in fixed positions. In the liquid state, particles are held together but have enough energy to break free to move around.
2. Define this scientific word and use it in context. 'melting'
Melting is when a substance changes from a solid state to a liquid state. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Particle spacing can be overemphasised at the expense of particle movement. Correction: Ensure pupils understand that although particles can move over each other, the forces of attraction mean that the particles are touching.
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