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^_^ MATERIALS ^_^

^_^ MATERIALS ^_^. What are materials?. There are two basic types of materials, metallic and non-metallic. . Difference between metals and non-metals. . Metals. Non-metals. Usually solid at room temperature. ( the exception being mercury )

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^_^ MATERIALS ^_^

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  1. ^_^MATERIALS^_^

  2. What are materials? • There are two basic types of materials, metallic and non-metallic.

  3. Difference between metals and non-metals. Metals Non-metals • Usually solid at room temperature. (the exception being mercury) • High melting points and boiling points.(this is because of the strong metallic bonds holding them together.) • Good conductors of heat and electricity. • Most are liquids and gases(e.g. oils, carbon dioxide) solids include, plastics and wood. • Often have low melting points and boiling points.(this is because the forces between them are weaker than in metals.) • Solid non-metals are poor conductors of heat and electricity.

  4. Uses for metals and non-metals in the home. • Metals- pots and pans, doors and gates, wires in electrical appliances. • Non-metals- plastics are used to cover electrical wires in appliances because they are very good insulators.

  5. ALLOYS

  6. What are Alloys? • An Alloy is a mixture of two or more metals. Alloys have better properties than separate metals, so we mix metals and non-metals so it can be HARDER and STRONGER than the original metal.

  7. Table of example of alloys and their uses.

  8. Corrosion

  9. What is corrosion? • Corrosion is a process in which metals are oxidised. The metals react with oxygen in air to produce metal oxides such as rust. The more reactive a metal is with oxygen, the faster it corrodes.

  10. What is meant by Rusting? • Rusting is the name used for the corrosion of iron and steel in the presence of oxygen and moisture, iron oxidises and gives rust (hydrated iron oxide)

  11. How does rusting occur? • Iron rusts when it comes into contact with water and oxygen.

  12. !!!How to prevent rusting!!! • Painting-can keep air and water away. • Galvanizing- means coating the iron with a layer of zinc which provides a protective layer. • Oiling- can prevent rusting by keeping away air and moisture. • Electroplating- means using electrolysis to cover over iron with another metal and so protecting it. (e.g. chromium plating)

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