Lesson focus: State properties emerge from particle arrangement, movement and spacing.
Compare solidA state of matter that keeps its own shape and volume, because its particles are held in place., liquidA state of matter that can flow and takes the shape of its container, but keeps the same volume. and gasA state of matter that spreads out to fill any container, because its particles are far apart and move quickly. using both particle modelThe idea that everything is made of tiny particles that are always moving. and macroscopic properties.
Build on earlier learning
The particle modelApply the particle-model rules to observable state properties.
Practical
Comparing solids, liquids and gases
- Compare whether each sample keeps its shape, flows, or fills its container.
- Try to compress a syringe of air and a syringe of water, each sealed at the tip.
- Explain each observation with the particle model.
Record: A table of properties linked to particle arrangement and movement.
Particles in solids, liquids and gases
Change the temperature of some water and watch its particles. The particles themselves do not change, only how they are arranged and how they move.
Controls
You will be successful when you can…
- Describe all three particle arrangements.
- Relate movement to shape and flow.
- Relate spacing to compressibility.
- Avoid drawing widely spaced liquid particles.
Words that carry the science
- state of matter
- Physical form described here as solid, liquid or gas.
- fixed volume
- A volume that changes very little under ordinary conditions.
- compressibility
- How readily volume decreases under pressure.
- vibration
- Repeated movement about a mean position.
- random motion
- Movement with continually changing direction.
Explain each state from arrangement and movement
01Solid
Particles are close in a regular or fixed arrangement and vibrateTo move quickly backwards and forwards on the spot. about mean positions. Strong constraints on changing neighbours explain fixed shape and volume.
02Liquid
Particles remain close together but can change neighbours and move past one another. This explains flow and container shape while preserving nearly fixed volumeTaking up the same amount of space whatever container it is in..
03Gas
Particles are widely separated and move rapidly in random directions. A gas fills its container and is compressible because large gaps can decrease. Quick comparison: in a solidA state of matter that keeps its own shape and volume, because its particles are held in place., particles are close together, in fixed places, and only vibrateTo move quickly backwards and forwards on the spot. (jiggle on the spot). In a gasA state of matter that spreads out to fill any container, because its particles are far apart and move quickly., particles are far apart and move quickly in all directions. The big gaps in a gas are why you can squash it, but you cannot squash a solid.
Explain liquid properties
Why does water flow yet remain difficult to compress?
- Liquid particles are close together.
- Small gaps leave little space to reduce, so compression is difficult.
- Particles are not fixed to the same neighbours.
- They move past one another, so the liquid flows.
How to make the reasoning visible: Use spacing for volume and neighbour changes for flow.
State property matrix
Link each observation to one model feature.
| State | Shape | Volume | Compressibility |
|---|---|---|---|
| Solid | Fixed | Fixed | Very low |
| Liquid | Container shape | Fixed | Very low |
| Gas | Fills container | Container volume | High |
| Unknown: flows, fixed volume | Container shape | Fixed | Very low |
Identify the unknown state and justify.
Why does a gas fill a container?
Why are solids and liquids very hard to compress, but gases are easy to compress?
Check your understanding
Answer from memory, then check against the suggested answer.
What is state of matter?
What is fixed volume?
What is compressibility?
Which state of matter can flow but keeps the same volume?
How do particles move in a solid?
A material flows but changes volume very little when pressed. Identify its state.
Why is “liquid particles are halfway apart between solid and gas” misleading?
Sand can be poured like a liquid. Is sand a liquid? Explain.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Answer the parts to compare the particles in a solid and in a gas.
How close together are the particles in each?
(1)Are the particles in fixed places, or free to move about?
(1)How do the particles move in each?
(1)Which one can you squash? Why?
(1)Total for this question: 4 marks
Command word: For compareA command word: say how two or more things are similar and how they are different., say something about both in each sentence, joined with “but”.