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.
Interactive activity - states of matter
Use this interactive states of matter diagram to see what happens to the particles inside substances when they are heated and change state. Select water, sodium chloride or iron and 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 physics 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 many ways to test yourself on OCR 21st Century physics and sharpen your skills.
Interactive quiz about temperature changes and energy, with video feedback to aid your understanding.
A ten-question quiz on the particle model and heating, with questions covering states of matter.
Sample exam questions based around matter, with advice for the exam, multiple choice, and using mathematical skills.
BBC Bitesize also has a range of general OCR 21st Century physics test pages, with:
Exam practice questions based on GCSE physics past papers.
Quick-fire quizzes with a refreshed batch of GCSE physics questions each time you come back.
Topic-based exam practice questions based on past papers, allowing you to choose the area of OCR 21st Century GCSE physics revision for your focus.
