1. solids, liquids and gases
7G Particle model of solids, liquids and gases
7G Particle model of
solids, liquids and gases
What is the world made of?
Solids, liquids and gases
The particle model

2. What is the world made of?
7G Particle model of solids, liquids and gases
What is the world made of?

3. 7G What is the world made of? - Big questions

4. Greek thinkers thought everything was made up of 4 things:
7G What is the world made of? - Ancient thinkers
Since ancient times the greatest thinkers have tried to understand and group the world around them.
Greek thinkers thought everything was made up of 4 things:
TEACHER’S NOTES
The material on this and the following slide could be used to discuss why people come up with different theories.

5. In India they added a fifth group:
7G What is the world made of? - Ancient thinkers
In India they added a fifth group:
The ancient Chinese had a slightly different view.
They believed the universe was made up of 5 components:
TEACHER’S NOTES
The material on this and the previous slide could be used to discuss why people come up with different theories.

6. A theory is an idea that explains observations.
7G What is the world made of? - Creating a theory
A theory is an idea that explains observations.
Scientists, like ancient thinkers, are curious about the world. They carry out investigations and produce theories about what they see.
But a theory doesn’t just appear by itself!
Creating a good theory involves several stages.
The following stages are in the wrong order.
Put them in the right order and explain your answer.
evidence
theory
observations
conclusion
data
prediction
Answer-
prediction
observations
data
evidence
conclusion
theory

7. Solids, liquids and gases
7G Particle model of solids, liquids and gases
Solids, liquids and gases

8. Everything in the Universe is made of matter.
7G Solids, liquids and gases - It’s a matter of fact!
Everything in the Universe is made of matter.
Matter is all the stuff around you – everything you can touch, see or smell.
There are 3 states of matter…

9. 7G Solids, liquids and gases - It’s a matter of fact!

10. A useful starting point is to think about their shape and volume.
7G Solids, liquids and gases - In a state!
You can investigate solids, liquids and gases to understand how they behave.
A useful starting point is to think about their
shape and volume.
TEACHER’S NOTES
- clarify definitions and distinction between “shape” and “volume”

11. solid liquid gas fixed shape fixed volume
7G Solids, liquids and gases - In a state!
Fill in the table with the answers to these testing questions:
Does it have a fixed shape?
Does it have a fixed volume?
solid
liquid
gas
fixed shape
fixed volume
TEACHER’S NOTES
- answers not revealed here
- space to fill in answers - complete by adding tick/cross on whiteboard
- students copy and complete own version of table

12. Does it conduct heat well?
7G Solids, liquids and gases - In a state!
Now answer some more testing questions about a solid, a liquid and a gas.
solid
liquid
gas
Is it easy to squash?
Does it conduct heat well?
Can it spread out?
Can it stretch?
Is it heavy for its size?

13. 7G Solids, liquids and gases – What are they made of?

14. 7G Solids, liquids and gases – What are they made of?
You can do the same “splitting experiment” if you think about a liquid or a gas.
Solids, liquids and gases are all made of tiny particles. This is called the particle theory.
TEACHER’S NOTES
But just how small are these particles?

15. 7G Particle model of solids, liquids and gases
The particle model

16. He also thought about the size of these particles.
7G The particle model - The necklace of Democritus
Democritus, an ancient Greek thinker, was one of the first to suggest the idea of particles.
He also thought about the size of these particles.
Democritus considered the particles in a grain of salt (one millimetre cubed).

17. Imagine you could take apart all the particles in this grain of salt.
7G The particle model - The necklace of Democritus
Imagine you could take apart all the particles in this grain of salt.
How long would the row of particle be?
Would it be long enough to make a necklace?
Next you arrange all the particles in a row.

18. 7G The particle model - The necklace of Democritus
Democritus never found out the answer to his salty puzzle. Thousands of years later, we know just how long the row of salt particles would be…
metres
That’s more than 33 times the distance from
the Earth to the Moon!
All that from just one grain of salt!
What does tell us about the number and size of the particles?

19. So next time you pour salt on your chips
7G The particle model - The necklace of Democritus
The number of particles is very, very, very, very, very, very, very, very, very, very ,very, very big!
The size of the particles must be very, very, very, very, very, very, very, very, very, very, very small!
So next time you pour salt on your chips
spare a thought for all those tiny salt particles!

20. Solids, liquids and gases behave in different ways.
7G The particle model - From theory to model
Solids, liquids and gases behave in different ways.
What does this tell us about their particles?
A theory is an idea that explains observations.
Scientists use a model to give a mental picture of what is happening in their investigation.
TEACHER’S NOTES
make link to students observations about properties of a solid, a liquid and a gas
Any theory about particles must be able to explain the differences between a solid, a liquid and a gas.

21. The particle model of matter describes: how particles are arranged
7G The particle model – Solids, liquids and gases
The particle model of matter describes:
how particles are arranged
how much energy particles have and how they move 
In some matter the particles are held together by forces of attraction.
TEACHER’S NOTES
- use the following animations to consider how the particle model explains the behaviour of solids, liquids and gases?
Use the particle model to decide if the forces of attraction are strong, weak or do not exist.

22. The particle model of a solid
7G The particle model – Solids, liquids and gases
The particle model of a solid

23. The particle model of a liquid
7G The particle model – Solids, liquids and gases
The particle model of a liquid

24. The particle model of a gas
7G The particle model – Solids, liquids and gases
The particle model of a gas

25. - are very close together in a fixed arrangement
7G The particle model – Solids, liquids and gases
solid particles…
- are very close together in a fixed arrangement
- have a small amount of energy
- vibrate but do not move
liquid particles…
- are close together but have no fixed arrangement
- more energy than solid particles
- vibrate and can move about
TEACHER’S NOTES
- use the following animations to consider how the particle model explains the behaviour of solids, liquids and gases?
gas particles
- are far apart and have no fixed arrangement
- have a large amount of energy
- move rapidly in all directions

26. Water can be a solid, liquid or a gas.
7G The particle model – Changing state
Water can be a solid, liquid or a gas.
Its state depends on how much energy
the water particles have.
ice
water
steam
If enough energy is added to or removed from the particles a change of state can occur.

27. freezing condensing melting evaporating
7G The particle model – Changing state
Match the change of state to the correct arrow on the diagram.
freezing condensing melting evaporating
ice
water
steam
What happens to the particles during each change of state?
CLUE: Think about their energy, their movement and the distance between them.

28. True or False? 1. The particles in gas have a large amount of energy.
7G The particle model – True or false?
True or False?
1. The particles in gas have a large amount of energy.
2. The particles in a solid have no forces of attraction between them.
3. The particles in a liquid are close together and have a fixed arrangement.
4. When a liquid freezes it becomes a gas.
5. Evaporation describes the change from a liquid to a gas.
6. When a liquid loses energy it becomes a gas.
7. A gas condenses to a liquid when its particles lose energy.
8. When the particles in a solid gain energy the solid melts.
TRUE
FALSE
FALSE
FALSE
TRUE
FALSE
TRUE
TRUE