Everything around us is made of tiny particles, too small to see. In a solid, particles are packed tightly and vibrate in place, giving it a fixed shape. In a liquid, particles are close but can move past each other, so it takes the shape of its container. In a gas, particles are spread far apart and move freely, filling whatever space they're in. Heating or cooling something can change it between these states.
Example
Ice (solid) melts into water (liquid) when heated, and water can be boiled into steam (gas). The water molecules themselves don't change — only how tightly packed and how fast-moving they are.
Key terms
Solid:
A state of matter with a fixed shape and tightly packed particles.
Liquid:
A state of matter that takes the shape of its container.
Gas:
A state of matter that spreads out to fill its container.
Questions
1. Ice is an example of a:
Solid
Liquid
Gas
None of these
2. Water (liquid) takes the shape of:
Nothing
Its container
A cube always
A sphere always
3. Steam is an example of a:
Solid
Liquid
Gas
None of these
4. In a solid, particles are:
Packed tightly and vibrating in place
Spread far apart
Moving freely everywhere
Not moving at all, ever
5. In a gas, particles are:
Packed tightly
Spread far apart, moving freely
Frozen in place
Non-existent
6. A solid has a:
Fixed shape
Shape that always changes randomly
No particles
Only gas particles
7. Heating ice turns it into:
Gas directly
Liquid water
A different substance
Nothing changes
8. Boiling water turns it into:
Ice
Steam (a gas)
A solid
Nothing
9. Which state of matter has particles that move past each other but stay close together?
Solid
Liquid
Gas
None
10. Cooling a gas enough can turn it into a:
Liquid
Solid only
Nothing, gases never change
Colour
11. Why does a gas fill up an entire room, but a solid doesn't?
Gas particles move freely and spread out
Gas has no particles
Solids are afraid of space
Gas is always visible
12. When water freezes, its particles:
Speed up and spread out
Slow down and pack tightly together
Disappear
Turn into gas
13. Which everyday item is closest to being a gas?
A rock
The air we breathe
A block of wood
A brick
14. The main difference between a liquid and a gas is:
Liquids have no particles
Gas particles are much more spread out and move more freely
Liquids are always frozen
There is no difference
15. Melting is the change from:
Solid to liquid
Liquid to gas
Gas to solid
Liquid to solid
16. Evaporation is the change from:
Solid to liquid
Liquid to gas
Gas to liquid
Solid to gas
17. Condensation is the change from:
Solid to liquid
Liquid to solid
Gas to liquid
Liquid to gas
18. Why does a puddle of water disappear on a hot day?
It evaporates into water vapour (gas)
It turns into a solid
It disappears with no explanation
It becomes lighter but stays liquid
19. Dry ice (solid carbon dioxide) turning straight into gas without becoming liquid is called:
Melting
Sublimation
Freezing
Condensation
20. If you cool water vapour (gas) in the air, it can condense into tiny water droplets, forming:
Clouds or fog
A solid rock
Nothing happens
Fire
21. Why can you squeeze a gas into a smaller container more easily than a solid?
Gas particles have large gaps between them that can be pushed closer
Solids have no particles
Gases are heavier than solids
There is no difference
Answer key (parent copy)
1. Solid
2. Its container
3. Gas
4. Packed tightly and vibrating in place
5. Spread far apart, moving freely
6. Fixed shape
7. Liquid water
8. Steam (a gas)
9. Liquid
10. Liquid
11. Gas particles move freely and spread out
12. Slow down and pack tightly together
13. The air we breathe
14. Gas particles are much more spread out and move more freely
15. Solid to liquid
16. Liquid to gas
17. Gas to liquid
18. It evaporates into water vapour (gas)
19. Sublimation
20. Clouds or fog
21. Gas particles have large gaps between them that can be pushed closer