Welcome to our online science lab where you can learn about the states of matter by interacting with the activity. Observe what happens when different substances change state.
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 in the Bitesize guide to the particle model and density and the energy, temperature and changes of state study guide.
What is happening when states of matter change?
In a system, the energy of the particles, which can be atoms or molecules, is known as the internal energy. It is the sum of the kinetic and potential energy of the particles.
Kinetic energy is due to the motion of the particles relative to each other. It increases as 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.
Potential energy is due to the position of the particles relative to each other. It increases when a solid changes state into a liquid, known as fusion, or when a liquid changes state into a gas, known as vaporisation.
How to calculate the energy required to change the state of a substance: multiply the latent heat (fusion or vaporisation) and mass of the substance. There is no change of temperature during a change of state.
Sublimation occurs when a solid changes state to a gas, or a gas to a solid. This is a change of state, so it changes the potential energy of the system.
States of matter – interactive activity
This interactive solid to liquid to gas diagram lets you see what happens to the particles inside substances when they are heated and change state. Select water, sodium chloride or iron and note the different melting and boiling points for these substances.
Look at the descriptions in the activity to discover if there is a change in kinetic energy or potential energy at each heating stage.
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.
The internal energy of the water is increasing when it reaches the boiling point, but is this an increase in kinetic energy or potential energy?
As the water is now changing state, this is an increase in potential energy.
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?
Check out the Bitesize guides to the particle model and density and energy, temperature and changes of state for video, audio, graphics and more physics revision notes written to the OCR Gateway GCSE combined science specification.
Do you prefer to revise on the go? BBC Bitesize and BBC Sounds have produced a series of GCSE revision podcasts, featuring a wide array of GCSE physics topics. For more information about potential energy and kinetic energy, listen to the energy series.
Where can I test my knowledge of states of matter and energy?
BBC Bitesize has a variety of ways to test yourself and practise your skills, including:
- Ten-question quizzes on the particle model and density and energy, temperature and changes of state.
Plus more general OCR Gateway combined science physics test pages, including:
- Exam practice quizzes based on combined science physics GCSE past papers.
- Quick-fire quizzes with fresh combined science physics GCSE questions each time you return.
- Topic-based exam practice questions based on past papers, letting you to choose which GCSE combined science physics topics you would like to focus on.
