Here in our online science lab you can find out more about states of matter and see what happens when different substances change state by interacting with the activity.
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 the particle model and heating.
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.
States of matter - interactive activity
Using this interactive states of matter diagram, see what happens to the particles inside substances when they are heated and change state. Choose between water, sodium chloride and iron, then note how the melting and boiling points for 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 the particle model and heating contains explainer text and infographics to explain changes of state, plus more physics revision notes written to the OCR 21st Century GCSE Combined Science specification. Explore the wider topic page for matter – models and explanations.
If you’d like to revise on the go, BBC Bitesize and BBC Sounds have developed the GCSE revision podcast series, covering a range of GCSE physics topics. Listen to the series about energy for more on this theme.
Where can I test myself on states of matter and energy?
There are lots of ways to test yourself and hone your skills, including a range of general OCR 21st Century Combined Science quiz pages:
A ten-question quiz on the particle model and heating, with questions covering states of matter.
Exam practice questions based on GCSE Combined Science physics past papers.
Quick-fire quizzes with a refreshed batch of GCSE Combined Science physics questions each time you come back.
Topic-based exam practice questions based on past papers, allowing you to choose the area of GCSE Combined Science physics revision for your focus.
