What are materials made from?
We obtain or make materials from either:
- Living things for exaple cotton,
- Non-living things, for example limestone, diamond and gold.
Some materials are synthetic and some are modified natural materials.
What are the properties of materials?
Some properties of materials are:
- Melting point,
- Strength in tension (pulling),
- strength in compression (squashing),
The effectivness and durability of a product depends on the propeties of the material it is made from.
A product which is durable lasts a long time before breaking or rotting.
Why do materials have particular properties?
A materials properties depend on how it's particles arearranged and held together:
- Very strong forces hold together the atoms in solid iron. An atom needs lots of energy to break out of this structure. So iron must get very hot before it becomes a liquid- it has a high melting point.
- The molecules in rubber can slide over each other easily. so rubber bends easily.
What is crude oil?
Crude oil is a mixture of hydrocarbon molecules of different lengths.
Hydrocarbons have molecules made from hydrogen and carbon only for example:
The petrochemical industry refines or seperates the components of crude oil to make:
- Fuels, for example petrol, diesel and keroson,
- Lubricants, for example vaseline,
- Raw materials for chemical synthesis, including those to make polymers.
What are polymers?
Polymers are very long molecules containing thousands of atoms. They are made when many small molecules join together. This type of chemical reaction is called polymerization.