Resource 3: Background information on states of matter

Some examples of materials that are harder to classify

Some materials appear to be a single substance but aren’t:

• Sand (or powders, like flour). This flows (like a liquid) but is made of tiny bits of solid. There is air in the gaps between the sand particles.
• Modelling clay (e.g. ‘plasticine’) is a mixture of a solid and a liquid. It loses its oil as it gets older, and becomes, dry, hard and unworkable.
• A cloud floats in the air (like a gas) but is composed of many tiny droplets of water in air.
• A jelly is a mixture in which small amounts of a liquid are mixed into another material which is a solid.
• Toothpaste is a mixture in which there are small amounts of a solid mixed in amongst another material which is a liquid.
• A foam is a mixture in which there is a gas mixed into another material which is a liquid.
• A sponge is a solid with air or liquid mixed with it. As a result it can be compressed, unlike most solids.
• Some liquids (like tomato ketchup) are thick and do not flow very well, but if you shake them, they become thinner and flow easily.