1 of 23© Boardworks Ltd 2007 Solids, liquids and gases

1 of 23 © Boardworks Ltd 2007

Solids, liquids and gases

© Boardworks Ltd 20072 of 23

States of matter


What are the substances described in the table?

(Clue: the first letters spell out another word for ‘substance’.)

mercury

aluminium

tin

ethanol

radium

iron

argon

liquid metal

solid used in aircraft

solid used to coat steel cans

intoxicating liquid

solid that rusts

radioactive solid

unreactive gas

solid used by Roman plumbers

Description Substance

lead

Different substances


At room temperature all substances exist in one of three physical states.

Three states of matter

solid liquid gas


Solid, liquid or gas?


The particle model


The difference between solids, liquids and gases can be explained by the particle model.

All substances are made up of particles.

The particles are attracted to each other. Some particles are attracted strongly to each other and others weakly.

The particles move around. They are described as having kinetic energy.

The kinetic energy of the particles increases with temperature.

The particle model


Particles in action


Solids, liquids and gases


has a high density as the particles are very close together

cannot be compressed as there is very little empty space between particles

has a fixed shape as the particles are held together tightly

cannot diffuse as the particles are not able to move

does not exert any pressure as the particles cannot move around.

What are the properties of solids?

A solid:


has a fairly high density as the particles are close together

cannot be compressed as there is very little empty space between particles

takes up the shape of its container as the particles can move

can diffuse as the particles are able to change places

can exert some pressure as the particles are able to move and hit the sides of the container.

What are the properties of liquids?

A liquid:


has a low density as the particles are far apart

can be compressed as there is space between particles

has no fixed shape as the particles move about rapidly in all directions

can diffuse as the particles are able to move in all directions

can exert a lot of pressure as the particles are able to move in all directions and hit the sides of the container.

What are the properties of gases

A gas:


Solids, liquids and gases: which one?


Diffusion


Where is the smell coming from and how does it spread out?

How do smells spread out?


Diffusion is the random movement of particles that causes them to spread out and mix with other particles.

For example, the smell of aftershave or perfume diffuses and is detected by people on the other side of a room.

Use the particle model to explain these facts about diffusion:

Diffusion happens more quickly at high temperatures than at low temperatures.

Diffusion occurs in liquids and gases, but hardly at all in solids.

Diffusion happens more quickly for gases than for liquids.

What is diffusion?


Diffusion in action: one gas


Diffusion in action: two gases


In this experiment, two gases diffuse towards each other in a sealed glass tube.

When the gases meet, they react and form a ring of ammonium chloride, which is closer to one end of the tube than the other. Which gas particles diffuse faster?

The ammonia particles have travelled further down the tube so they must have diffused at a faster speed.

cotton wool soaked in ammonia

gases meet here

cotton wool soaked in hydrochloric acid solution

Rate of diffusion


Summary activities


diffusion – The process in which particles randomly move and spread out in gases and liquids.

gas – The state of matter in which particles can freely move, and in which substances have no fixed volume or shape.

liquid – The state of matter in which particles are close together but free to move, and in which substances have a fixed volume and assume the shape of their container.

matter – The stuff that everything is made of.particle – The smallest unit of matter.pressure – The force produced when particles move

against a surface.solid – The state of matter in which particles are close

together and cannot move, and in which substances have a fixed shape and volume.

Glossary


Anagrams


Multiple-choice quiz

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1 of 23© Boardworks Ltd 2007 Solids, liquids and gases