14.1Unit 2: States of matter, atoms and compounds

Solids liquids and gases — Cambridge Checkpoint Science 0893 Revision Notes & Topical Questions

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📚 Cambridge Checkpoint Science 0893 Hub / Topical Revision

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Lesson summary

14.1 Solids, liquids and gases — CHECKPOINT (CHEMISTRY) notes: Classify matter as solid, liquid or gas and explain the properties of each state with particle theory.Matter = everything you can see and feel; it is sorted into three states: solid, liquid and gasProperty = a way a s…

Compressed
Hypothesis
Solid shape
Compression
Flow — liquids and gases flow; solids do not
Gases — generally cannot be seen or felt, but can sometimes be smelled or felt as moving air

Section 1 of 7Matter and the states of matter

1Matter

Matter everything you can see and feel; it is sorted into three states: solid, liquid and gas

2Property

Property a way a substance behaves, such as whether it can be poured or compressed

3Flow

Flow liquids and gases flow; solids do not

4Compressed

Compressed squashed into a smaller volume

Section 2 of 7Properties of solids, liquids and gases

Property	Solid	Liquid	Gas
Shape	Keeps the same shape	Takes the shape of its container	Fills any closed container
Volume	Fixed	Fixed, whatever the container	Can change
Can be poured	No	Yes	Flows like a liquid
Can be compressed	No	No	Yes, very easily
Weight	—	—	Weighs very little

Gases
- generally cannot be seen or felt, but can sometimes be smelled or felt as moving air

Section 3 of 7Particle theory

Particle theory

Particle theory all matter is made of tiny particles, too small to see, arranged differently in solids, liquids and gases

Hypothesis

Hypothesis a suggested explanation that has not yet been proved and can be tested

Theory

Theory a hypothesis that has been tested and widely accepted as valid by scientists

Section 4 of 7Arrangement of particles

	Solid	Liquid	Gas
Arrangement	Fixed pattern, regular rows	Close together, no pattern	Far apart, spread out
Touching	Tightly packed, touching	Touching	Not touching
Movement	Vibrate in position	Slide past each other	Move about freely and quickly
Forces between particles	Strong	Weak	None (very weak)

Section 5 of 7Explaining the properties

1Solid shape

Solid shape strong attractive forces hold the particles in a fixed pattern, so a solid keeps its shape and cannot flow

2Liquids

Liquids particles touch but slide past each other, so a liquid flows and takes the shape of its container
The forces are weak enough to allow movement but strong enough to hold the particles together.

3Gases

Gases particles are far apart and move quickly in all directions with no attractive forces, so a gas has no fixed shape or volume

4Compression

Compression solids and liquids cannot be compressed because their particles already touch;
- a gas can because squashing pushes particles closer together

5Flow

Flow matter can only flow if its particles can move past one another

6Vacuum

Vacuum a space with no particles at all

Section 6 of 7Key terms

Term	Meaning
Matter	Everything you can see and feel; it exists as solid, liquid or gas.
Particle	A tiny portion of matter, too small to see.
Compressed	Squashed into a smaller volume.
Vacuum	A space containing no particles.
Vibrate	Move quickly to and fro about a fixed position.
Hypothesis	A suggested explanation that can be tested.
Theory	A tested hypothesis that is widely accepted.

Section 7 of 7Exam technique

Saying particles themselves expand when heated — they move further apart but do not get bigger.

Saying liquids can be compressed — their particles already touch.

Saying a gas has a fixed volume — a gas fills whatever container it is in.

Using theory to mean a guess — a theory is a tested, accepted explanation.

Last updated: 12 October 2026