Here in our online science lab you can find out more about changes of state. See what happens at the particle level when different substances are heated by interacting with the activity.
What are the three common states of matter?
Solid, liquid and gas are the three main states of matter. 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. This is explained by the kinetic theory of matter.
Learn more in our study guide about solids, liquids and gases.
How do substances change state?
The amount of energy needed to change state depends on the strength of attraction between the particles. Substances with stronger forces of attraction will have higher melting and boiling points.
Learn more about this process in our study guide about changes of state.
Higher tier only - the particle model shows all particles as solid spheres with no forces between them. In reality, atoms, molecules and ions are different shapes and sizes, so the model is simplified.
Interactive activity - changes of state
What type of change is a change of state? This interactive activity will help you to find out what happens to the particles in substances when they are heated. Select a material from water, sodium chloride or iron and note how the melting and boiling points for these substances differ.
Test your understanding of the changing states of matter
In which state do the substances have the least energy?
Solid.
In which state is the average distance between the particles greatest?
Gas.
Between D and C on the graphs the substances are condensing. Is energy being given out to the surroundings or being taken in from the surroundings?
Energy is being transferred to the surroundings.
If a sample of sodium chloride has a temperature of 1300 °C, is it a solid, liquid or gas?
Liquid.
Based on the melting point of water, sodium chloride and iron, explain which substance has the strongest forces of attraction between the particles?
Iron, because it has the highest melting point. The structure of iron is a positive ion lattice surrounded by delocalised atoms. It takes a lot of energy to break down the lattice due to the strong forces of attraction between the positive lattice and negative electrons.
Where can I find out more about changes of state?
The BBC Bitesize guide about change of state contains explainer text and infographics to explain the concept, plus more chemistry revision notes written to the OCR 21st Century GCSE combined science specification. Explore the wider topic page about air and water, and the earth’s atmosphere.
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 chemistry topics. Listen to the series about bonding, structure and properties or skip straight to the episode about states of matter.
Where can I test my knowledge of the changing states of matter?
There are lots of ways to test yourself and hone your skills, including test pages designed for the OCR 21st Century combined science exam spec.
A ten-question quiz on the Earth’s atmosphere, including questions covering states of matter.
Exam practice questions based on GCSE combined science past papers.
Quick-fire quizzes with a refreshed batch of GCSE combined science chemistry 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 chemistry revision for your focus.
