Particle Theory
The particle model states that all matter is made of tiny particles that are always moving and have spaces between them.
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Play with the controls to see the idea in action.
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The particle model states that all matter is made of tiny particles that are always moving and have spaces between them.
- Particles move faster when heated
- Gases can be compressed because of the large gaps
- Explains diffusion and pressure
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Particle Theory?
Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Particle Theory. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.
Check that you can explain Particle Theory in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Particle Theory helps you explain why substances behave as they do, from cleaning products and food to medicines.
Particle Theory in detail
Particle theory says that all matter is made of tiny particles (atoms, molecules or ions) that are constantly moving, with gaps between them. The amount of movement increases with temperature, and there are forces of attraction between particles.
It explains why solids, liquids and gases differ, why gases exert pressure on their containers, why heating makes substances expand and how changes of state occur. Evidence for particles includes diffusion and Brownian motion. The model is simple, but it has limits, as particles are not really solid spheres.
How the interactive helps you understand Particle Theory
Watch the gas particle model in the interactive. Use any sliders or buttons it offers to change the values and see how the gas particle model responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Particle Theory.
Real-life uses and examples
- Use Particle Theory to explain what happens in a lab experiment and why.
- Link Particle Theory to everyday products such as cleaning agents, food and medicines.
- Read a chemical equation or diagram and work out what Particle Theory shows.
Common mistakes to avoid
- Describing what happens without explaining the particles or bonds involved.
- Mixing up the names of substances or ions when you describe Particle Theory.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Particle Theory
What is Particle Theory?
The particle model states that all matter is made of tiny particles that are always moving and have spaces between them.
What are the most important points about Particle Theory?
The main points are: Particles move faster when heated; Gases can be compressed because of the large gaps; Explains diffusion and pressure.
Why is Particle Theory useful?
Understanding Particle Theory helps you explain why substances behave as they do, from cleaning products and food to medicines.
How can I practise Particle Theory?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Particle Theory?
Related topics in Chemistry include Atomic Structure, History of the Atom, Group 1: Alkali Metals.