What are materials made of?
            1. Solids, liquids and gases
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Materials and properties
We are all used to describing things around us as being solid, liquid or gas. These are the three states of matter.

You will have some general ideas about what each state of matter looks like and how it behaves. That's how you decide whether to call a material a solid, liquid or gas.

Photo of weightlifter
Picture 1.1. A strong man. What about the can? What are its properties?
Some properties of solids, liquids and gases
We use the word property to describe one aspect of what a material is like. Some words we use to describe the properties of materials are: strong, hard, flexible, runny and compressible.

Let's look at some of the properties that help us to decide on whether a material is a solid, liquid or gas.

Solids Liquids Gases
Keep the same shape Take the shape of the container Fill the whole container
Stay where they are put Runny - can be poured Spread out quickly
Are difficult to move through Are quite easy to move through Are very easy to move through
Can’t be compressed Are very difficult to compress Compressible - easy to compress
Photo of pond
Picture 1.2 . The water in the pond fills the shape of the hole in the ground.

Being flexible about properties
The trouble with the ideas shown in the table is that they are not perfect. The descriptions don't work for all solids, liquids and gases. This doesn’t mean that the ideas are of no use, but it does mean we have to take care how we use them. Sometimes a material only has some of the properties in the table. And sometimes a material has the properties of more than one of the states of matter.
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Question 1
Look at the table below. Are the named materials solids, liquids or gases? Click on the button to make your choice. For each material, think of any property it has that doesn’t fit the expected pattern. Type your answer in the third column.
Material States Unexpected properties
Sand
Toothpaste
Jelly
Wet mud
Treacle
A sponge