Year 7 Science · Unit 2 · Lesson 2
Foundation Worksheet
Learning Goals
Fill the gap: the five rules
Choose the correct word from the word bank. Each word is used at most once. Two words are not needed: cross them out.
All matter is made of tiny . They are always , even in a solid, where they on the spot. Particles each other, and there are empty between them. Adding makes the particles move faster.
Match each state change to its meaning
Write the letter of the correct meaning next to each state change. Each letter is used once.
| State change | Letter | Meaning |
|---|---|---|
| Melting | A. Solid turns straight to gas, skipping the liquid (a block of dry ice shrinking) | |
| Freezing | B. Liquid turns to gas (a puddle drying in the sun) | |
| Evaporation | C. Solid turns to liquid (an ice cube on a hot day) | |
| Condensation | D. Gas turns straight to solid, skipping the liquid (frost forming on a windscreen) | |
| Sublimation | E. Gas turns to liquid (droplets forming on a cold drink can) | |
| Deposition | F. Liquid turns to solid (water in an ice-cube tray) |
1. The smell of cooking spreads through a house by diffusion. Say what diffusion is, and name one thing that makes it happen faster.
Sort it: energy in or energy out?
Does each change absorb energy or release it? Write each change in the correct box. The boxes do not hold the same number of items.
Absorbs energy
Releases energy
2. Draw a particle diagram of a solid, a liquid and a gas side by side. Use small circles for particles, with about eight in each diagram, and label each one.
Read the data: heating a beaker of water
Scenario
A class heats a beaker of water on a hot plate. The hot plate stays on the whole time. They read the thermometer every 2 minutes.
| Time (min) | 0 | 2 | 4 | 6 | 8 | 10 | 12 |
|---|---|---|---|---|---|---|---|
| Temperature (°C) | 20 | 42 | 64 | 86 | 100 | 100 | 100 |
Source: sample class results.
3. At what temperature did the water start to boil? What is the name for this temperature?
4. The hot plate kept adding heat, but the temperature stopped rising after 8 minutes. Use the particle model to explain why.
5. An ice block is taken out of the freezer and left in the sun. It melts into a puddle, and later the puddle dries up. Use the particle model to explain what happens to the particles at each stage.
Fill the gap: the five rules
particles; moving; vibrate; attract; spaces; heat. Not used: air, grow.
Match each state change to its meaning
Melting → C; Freezing → F; Evaporation → B; Condensation → E; Sublimation → A; Deposition → D.
Question 1
Particles spreading from where they are crowded to where they are less crowded (1). Any one: a higher temperature; spreading through a gas rather than a liquid; smaller particles (1). [2 marks]
Sort it: energy in or energy out?
Absorbs energy: ice block melting; puddle drying; dry ice shrinking; water boiling. Releases energy: frost forming; droplets on a cold can; water freezing in a tray.
Question 2
Solid: particles touching, packed in neat rows (1). Liquid: particles touching but jumbled, not in rows (1). Gas: particles far apart and spread out at random (1). [3 marks]
Read the data: heating a beaker of water
3. 100 °C (1); the boiling point (1). [2 marks]
4. From 8 minutes the energy goes into pulling particles out of the liquid to make gas (1), not into making them move faster, so the temperature stays at 100 °C (1). [2 marks]
Question 5
Marking guide: 1 ice: particles close-packed in fixed rows, vibrating on the spot; 1 the sun’s heat gives the particles more energy, so they vibrate faster and break free of their fixed positions: melting; 1 liquid: particles still close together but sliding past each other; 1 evaporation: particles at the surface gain enough energy to escape into the air as a gas, far apart; 1 it is still water (H₂O) throughout; only the arrangement and speed of the particles change. [5 marks]
Model answer: In the ice, the particles are in fixed rows, vibrating on the spot. The sun’s heat makes them vibrate faster until they break free and the ice melts. In the puddle the particles are close together but slide past each other. Particles at the surface gain enough energy to escape into the air as water vapour: evaporation. It is still water; the particles are just arranged differently.
Common error: saying the particles themselves melt, grow or disappear.