The interactive activity on this page is designed to visualise the states of matter and what happens when substances change state. You can use it to help your revision.
How many states of matter are there?
There are three main states of matter: solid, liquid and gas. When a substance changes state, this is a physical change because no new substances are produced and the change is reversible.
The particles in solids, liquids and gases change arrangement and motion when a substance is heated or cooled down. This is explained by the kinetic theory of matter.
Read more about the states of matter in our study guide about kinetic theory.
What is happening when states of matter change?
The energy stored in the particles in a substance changes when the substance is heated. This can either make the temperature increase or change the state of the substance.
When the substance is heated the particles move faster and the temperature increases.
How to calculate the energy required to raise the temperature of a substance: multiply the specific heat capacity of the substance, the mass and required temperature change.
When the substance changes state there is no change in mass or temperature.
How to calculate the energy required to change the state of a substance: multiply the specific latent heat and mass of the substance.
Sublimation occurs when a solid changes state to a gas, or a gas to a solid.
Interactive activity - states of matter
This interactive states of matter diagram will help you to see what happens to the particles inside substances when they are heated and change state. Pick between water, sodium chloride and iron, then note how the melting and boiling points of these substances are different.
Test your understanding of the states of matter
How would you describe the change in the particle arrangement when the iron particles reach the melting point?
The particles are no longer vibrating in fixed positions. They start to slip and slide over each other.
What is the boiling point of sodium chloride?
1465 °C
When solid sodium chloride is being heated, how does the motion of the particles change?
As the temperature increases, the particles vibrate rapidly.
Which parts on the heating and cooling graph show a change of state?
Sections B and D show changes of state.
Where can I learn more about states of matter and energy?
The BBC Bitesize guide to kinetic theory contains infographics and text to explain concepts such as the changing states of matter, plus more physics revision notes written to the WJEC GCSE physics specification.
Want to revise on the go? The GCSE revision podcasts from BBC Bitesize and BBC Sounds cover a range of GCSE physics concepts. For more on this topic, listen to the series about energy.
Where can I test my knowledge of kinetic theory?
BBC Bitesize has many ways to test yourself with physics revision practice.
GCSE physics exam-style questions based on past papers.
GCSE physics quick-fire quizzes with a new set of questions when you return.
Topic-based practice questions for GCSE physics based on past exam papers. This quiz lets you choose the topics you want to focus on.
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