Teacher sheet · Ages 10–11 · about 45–50 minutes
States of matter and the particle model
Lesson page: echoesof.science/school/states-of-matter/ages-10-11/ · Pupil worksheet: echoesof.science/school/states-of-matter/ages-10-11/print/
Learning aims
- Describe solids, liquids and gases with the particle model.
- Name the changes of state, including sublimation.
- Know water's melting and boiling points and that temperature is constant during a change of state.
- Plan and carry out a fair test.
Lesson plan
| Time | Activity |
|---|---|
| 5 min | Starter: why can you pour water but not a brick? |
| 10 min | Read the text and draw particle diagrams. |
| 20 min | Which melts first? fair test in groups. |
| 5 min | Compare results with the class. |
| 5 min | Quiz or Name that change. |
Materials for the experiment
- Four identical small plates or foil cases
- Four solids of the same size: an ice cube, a square of chocolate, a cube of butter, a piece of a wax candle
- A tray of warm tap water (not hot: about 40 °C, checked by the teacher) to float the cases on
- A stopwatch
Safety: Use only warm tap water (about 40 °C), never boiling water. No flames: do not light the candle. Don't eat the chocolate or butter afterwards.
Common misconceptions
| Pupils may think… | Actually… |
|---|---|
| Particles in a solid don't move. | They vibrate about fixed positions. |
| The steam you see above a kettle is a gas. | The visible cloud is tiny drops of liquid; water vapour itself is invisible. |
| Melting and dissolving are the same. | Melting is a change of state caused by heat; dissolving is mixing into a liquid. |
Worksheet answers
- Solid: tightly packed, regular; liquid: close but jumbled; gas: far apart.
- Evaporation (or boiling); condensation.
- The energy taken in is used to pull the particles apart, not to raise the temperature.
- It depends on your results. Anything with a melting point above the water's temperature (about 40 °C) does not melt; the others melt, the lowest melting points first.
Quiz answers
- In which state are the particles far apart and moving freely? Gas. Gas particles move independently except when they collide.[2]
- Why does a liquid take the shape of its container? Its particles can slide past each other. Liquid particles stay close but move past each other.[2]
- What is the change from gas to liquid called? Condensation. Gas to liquid is condensation.[3]
- At what temperature does water boil at normal air pressure? 100 °C. Water's normal boiling point is 100 °C at 1 atm.[3]
- Why does ice float? Ice is less dense than liquid water. When water freezes its density drops by about 9%.[5]
- Dry ice turns straight from solid to gas. This is called… sublimation. It never becomes a liquid.[3]
Going further
Weigh an ice cube in a sealed bag, let it melt, and weigh it again. Does the mass change? What does that tell you?
Sources used in this lesson
- [1] Chemistry: Atoms First, 1.2 Phases and Classification of Matter (OpenStax, Rice University): reliability High
- [2] Chemistry (OpenStax adaptation), 10.1 Intermolecular Forces (OpenStax Chemistry, hosted by Lumen Learning (CC BY 4.0)): reliability High
- [3] Chemistry, 10.3 Phase Transitions (OpenStax, Rice University): reliability High
- [5] Water Density (U.S. Geological Survey, Water Science School): reliability High
Full list with links and a note on each source's reliability: echoesof.science/school/states-of-matter/sources/
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