When a smell spreads, particles move away from where they originated. This is called diffusion.

# Solids Liquids and Gases 01

The three states of matter are solids, liquids and gases. Matter is a general term for the substance of which all physical objects are made. All matter is actually made up from atoms. Matter is very varied but it has predictable properties. The kinetic theory is a useful idea that can be applied to any matter in order to explain or describe its physical behaviour. The basis of the kinetic theory is that you need to imagine all matter as being made up from small, spherical particles.

In a solid, the particles are imagined as being close together and held together by strong forces. They can vibrate in any direction but they cannot change places. In a liquid, the particles are free to change places and are still held together by forces, but the forces are weaker than in the solid form. You can imagine the particles whizzing about in all directions, constantly bumping into other particles. A few particles are moving fast enough to escape from the liquid. In a gas, the particles are not held together by any forces and are moving the fastest. You can think about them moving around even faster than when the material was a liquid. They are much further apart than when they were in either a liquid or a solid form and travel a lot further, on average, before they collide with other particles.

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1. When a solid changes to a liquid, it .......
Ice melts at 0° C
2. Which is the most dense substance in this list?
The most abundant metal in the Earth's crust is Aluminium. Aluminium is a low density metal
3. When a smell spreads, particles move away from where they originated. This is called .......
It takes a while for the smell to spread because the 'smelly' particles collide with particles of the air and travel around in random directions
4. If matter has energy taken away .......
As matter is cooled down, the particles move more slowly and therefore can pack closer together
5. If you reduce the volume of a gas .......
The gas particles are moving at the same speeds as before but there are more of them in a smaller space
6. Which of these statements about solids is true?
The particles are fixed in place so the shape of a solid object does not change unless something is done to it e.g. hit it with a hammer
7. When a gas changes to a liquid, it .......
If a gas has energy taken away (is cooled) the particles slow down
8. The state of matter which has very low density is .......
Hydrogen is the gas with lowest density
9. Which will have the highest boiling point?
Pure water boils at 100° C, adding salt makes it boil at a slightly higher temperature. The exact temperature depends on the amount of salt added
10. A balloon is filled with gas. Inside the balloon the gas particles .......
The particles in a gas are moving a lot faster than those in a liquid or solid

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