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Everything is made out of particles. These can be atoms or molecules. We use particles to explain how materials behave whether as a solid, a liquid or a gas.
If we heat a solid then it melts and becomes a liquid, if we cool a liquid it freezes to become a solid. These changes are called 'change of state'.
If you release particles from a source they will diffuse (spread out) from the area where they started (in high concentration) to the rest of the room (where they are in low concentration.) More information on a specialised type of diffusion involving water called osmosis can be found here.
Solutions of particles can be made by dissolving a solute (eg salt) into a solvent (eg water) to make a solution (eg salt water).
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Teaching Resources
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Lessons on 'Properties of Solids, Liquids and Gases', 'The particle theory', 'Changes of State' and 'Melting and Bioling Point' from www.skoool.co.uk |
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A simple program about solids, liquids and gases - use the help function to get you started, from www.bbc.co.uk |
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See what happens as you heat and cool water - use the help function to get you started, from www.bbc.co.uk |
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This simulation shows how particles behave. It starts off by showing some red and blue particles in tow different containers. Try changing the temperature (which is in Kelvin - a different scale), the size (mass) or the number of particles to see how they behave. If you remove the barrier you can see that the particles will diffuse across the space.
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Reversible and Irreversible Changes Find out which solutions dissolve and which don't - use the help function to get you started, from www.bbc.co.uk |
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If a can is filled with a little water and heated, then placed quickly into cold water it will collapse. These videos show this being done with drinks cans and an oil drum. |
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Revision sections from BBC Bitesize for Key Stage 3. |
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