# The particle model

> Grade 7: particles in solids, liquids and gases, diffusion, changes of state explained by particles, gas pressure, mass is conserved.

Source: https://olyclass.com/library/science-g7-particle-model-en/

- Subject: Science
- Level: Grade 7
- Quiz: 16
- Play it free on one screen (projector, TV or whiteboard): https://olyclass.com/library?play=science-g7-particle-model-en
- Copy and edit it: https://olyclass.com/library?copy=science-g7-particle-model-en
- Games it plays well in: [Penalty Kick](https://olyclass.com/classroom-games/penalty-kick/), [Fishing Pond](https://olyclass.com/classroom-games/fishing-pond/), [Claw Machine](https://olyclass.com/classroom-games/claw-machine/), [Lucky Drop](https://olyclass.com/classroom-games/lucky-drop/)

## Questions

1. In which state of matter are the particles packed closely in a regular pattern? (Gas / Liquid / Solid / Steam)
   Answer: Solid
2. Which state of matter has particles that are far apart and move freely? (Gas / Ice / Liquid / Solid)
   Answer: Gas
3. The particles in a solid are completely still and never move at all.
   Answer: False
4. Why can a liquid be poured? (Its particles are far apart / Its particles are fixed in place / Its particles are very small / Its particles can slide past each other)
   Answer: Its particles can slide past each other
5. What is the spreading of particles from a high to a low concentration called? (Condensation / Diffusion / Evaporation / Melting)
   Answer: Diffusion
6. A smell of baking spreads across a room. Which explains this? (Particles of gas spread out by diffusion / The air heats the particles up / The particles get bigger / The particles stop moving)
   Answer: Particles of gas spread out by diffusion
7. Diffusion is faster in a gas than in a liquid. Why? Give a reason about particles.
   Answer: Gas particles are far apart and move faster and more freely
8. What happens to the particles of a solid when it melts? (They gain energy and can move past each other / They get smaller / They move further apart than in a gas / They stop vibrating)
   Answer: They gain energy and can move past each other
9. What is the change of state from gas to liquid called?
   Answer: Condensation
10. When water freezes, its particles stay the same and only their arrangement and movement change.
   Answer: True
11. What causes gas pressure on the walls of a container? (Particles colliding with the walls / Particles getting heavier / Particles melting on the walls / Particles sticking to the walls)
   Answer: Particles colliding with the walls
12. A gas is squeezed into a smaller space at the same temperature. What happens to its pressure? (It becomes zero / It decreases / It increases / It stays the same)
   Answer: It increases
13. Heating a sealed gas makes its pressure rise. What do the particles do differently?
   Answer: They move faster and hit the walls harder and more often
14. Ice melts in a sealed bag and nothing escapes. How does the water's mass compare with the ice? (It is less / It is more / It is the same / It is zero)
   Answer: It is the same
15. When a puddle evaporates, the mass of water disappears from the universe.
   Answer: False
16. Why is mass conserved when a substance changes state? (Some particles disappear / The number of particles stays the same / The particles become bigger / The particles get lighter)
   Answer: The number of particles stays the same