Obtaining and using metals

• metals are extracted from ores in the earth's crust
• Unreactive metals are found in the earth as uncombined elements
• Most metals are extracted from there ores by:
  • heating with carbon
  • electrolysis
• The method used to extract a metal is related to its position on the reactivity series and cost of the extraction process
• Electrolysis word equation example:
  • Water à hydrogen + oxygen
• Heating with carbon word equation example:
  • Iron oxide + carbon à iron + carbon dioxide

• Oxidation is the gain of oxygen
• Reduction is the loss of oxygen
• Extraction of metal involves reduction of ores
• Oxidation of metals results in corrosion
• A metals resistance to oxidation is related to its position on the reactivity series
• Oxidation word equation example:
  • iron + oxygen -> iron oxide
• Reduction word equation example:
  • aluminium oxide -> aluminium + oxygen                                                             

• Advantages of recycling:
  • Natural reserves of metal ores will last long
  • For most metals, less energy is needed to recycle them than is needed to extract them.
  • Recycling reduces the need to mine ores.  Mining can damage the landscape and create noise and dust pollution
  • Recycling produces less pollution
  • More recycling means that less waste metals are disposed of in landfills

• Most metals are:
  • good conductors of heat
  • good conductors of electricity
  • Ductile (can be drawn into wires)
  • Malleable (can be hammered into shape)
  • shiny
  • have high boiling and melting points
  • Some are magnetic
•  Aluminium:
  •  Has low density
  • Does not corrode
  • Used in making aeroplanes and cars
•  Copper:
  •  Good electrical conductor
  • low reactivity
  • does not react with water
  • used in water pipes and electrical cables

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• Gold:
  • Very unreactive
  • Does not corrode
  • Very attractive
  • One of the best electrical conductors
  • Used inside most electrical devices and for jewellery
• Steel:
  • Mixture of iron with carbon and other metals.
  • Stronger and harder than Iron
  • Used to make bridges, cars, electrical goods, frames for buildings and machinery

• An alloy is a mixture of metals to improve their properties.
• Alloys have different size atoms in them which stop each layer from sliding over each other
• Shape memory alloys return to their original state with a change in condition e.g. heated