Welcome to our online science lab where you can learn about changes of state by interacting with the activity. Observe what happens when different substances are heated.
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.
Discover 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.
Investigate 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
This interactive activity will help you to answer the question: what type of change is a change of state? Select a material from water, sodium chloride or iron, note how the melting and boiling points for these substances differ, and find out what happens to their particles when they are heated.
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?
Check out the BBC Bitesize study guide on changes of state and the particle model for audio, graphics and more chemistry revision notes written to the OCR Gateway GCSE chemistry 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 chemistry topics. Listen to the entire series about bonding, structure and properties or skip to the episode about states of matter.
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:
A ten-question quiz on the particle model, with numerous questions about changing states of matter.
Sample exam questions about particles, with advice for multiple choice, structured, practical and six-mark questions.
Bitesize also has more general OCR Gateway chemistry test pages, including:
Exam practice quizzes based on chemistry GCSE past papers.
Quick-fire quizzes with fresh chemistry GCSE questions each time you return.
Topic-based exam practice questions based on past papers, letting you choose which GCSE chemistry topics you would like to focus on.
