Metals and Polymers

• What is an alloy?

  A material that is made up of at least two different chemical elements, one of which is a metal.
• What is a base metal?

  The most important metallic component of an alloy
• What are the alloying agents?

  The other components of an alloy.
• What is a substitutional alloy?


  When the atoms of the alloying agent replace the atoms of the main metal.

  
  

  Example: Brass

  
• What is an interstitial alloy?


  When the agent atoms slip in between the interstices of the main metal atoms.

  
  

  Example: Steel

  
• Components of brass

  70% Copper, 30% Zinc
• Uses of brass

  • Hinges
  • Door handles
  • Fittings on boats and ships
  • Musical instruments
• Components of bronze

  95% Copper, 5% Tin
• Uses of bronze

  • Statues
  • Ornaments
  • Bells
• Components of amalgam


  Mercury, Silver, Tin, Copper, Zinc
• Uses of amalgam


  Dental fillings
• Components of solder


  Tin, lead
• Uses of solder

  • Joining metals together
  • Electrical connections
  • Low-friction bearings
• Components of stainless steel

  Iron, chromium, carbon, nickel, manganese
• Uses of stainless steel

  • Jewellery
  • Medical tools
  • Tableware
• Four metals that are found as native elements

  • Silver
  • Platinum
  • Copper
  • Gold
• Metals from the most reactive to least reactive

  K, Na, Ca, Mg, Al, Zn, Fe, Ni, Sn, Pb, Cu, Ag, Au
• Hydrogen is formed when a metal reacts with an acid.
• Iron is extracted from haematite.
• Aluminium is extracted from bauxite.
• Lead is extracted from galena.
• Uranium is extracted from pitchblende.
• Open-cut mining is used for ores found close to the surface
• Four problems associated with open-cut mining

  • Unsightliness
  • Pooling of water
  • Dust being blown into surrounding areas
  • Destruction of land above the ore
• Underground mines are used for the mining of deep ores.
• Four problems associated with underground mines

  • Water penetration
  • Possible collapse
  • Venting of poisonous and explosive gases
  • Provision of fresh air for the miners
• Metals that are extracted by electrolysis

  • Potassium
  • Sodium
  • Calcium
  • Magnesium
  • Aluminium
• Metals that are extracted by heating with carbon or carbon monoxide

  • Zinc
  • Iron
  • Nickel
  • Tin
  • Lead
• Metals that are extracted by roasting in the air

  • Copper
• Benefits of recycling metals

  • Can slow metals to run out
  • It is cheaper to recycle than it is to produce aluminium
• Oxygen and water are required for iron to rust.
• Salt and heat speed up the rate at which iron rusts.
• 5 ways of protecting a Metal from rusting

  • Painting
  • Adding layers of grease/oil
  • Coating in plastic
  • Tin plating
  • Chromium plating
• What is sacrificial protection?

  A method of preventing corrosion by attaching a more reactive metal to the metal that needs protection.
• Metals that would provide sacrificial protection to iron:

  K, Na, Ca, Mg, Al, Zn
• Use of polystyrene

  Packaging
• Use of polyvinyl chloride

  Pipes
• Use of polytetrafluoroethene (Teflon)

  Non-stick coating
• Use of polyethene

  Cling wrap
• Thermoplastic polymers

  • Melt when heated
  • Have weak bonds between the chains
  • Can be reshaped