Topic 3: Metals and Alloys

HideShow resource information
View mindmap
  • Topic 4: Metals
    • Metal Extraction
      • Most metals are extracted from ores found in the Earths's crust.
        • Unreactive metals are found in the Earth as uncombined elements.
      • Most metals are extracted from their ores by heating with carbon, such as iron is, or through electrolysis, like aluminium is.
        • The method used to extract the metal is based on its place in the reactivity series.
          • The more reactive a metal is, the harder it is to extract.
            • The harder a metal is to extract, the more it costs to extract. Electrolysis is more expensive than carbon heating due to the cost of electricity.
          • Metals up to and including Zinc are extracted by carbon heating.
          • Potassium, Sodium, Calcium, Magnesium, and Aluminium all require electrolysis. Electrolysis decomposes metals into their compounds.
          • Gold, silver and platinum are all found as uncombined elements.
    • Redox
      • Oxidation is the gain of oxygen, reduction is the loss of oxygen.
      • The extraction of metals involves reduction of ores. Most ores are found as oxides.
      • The oxidation of metals results in corrosion.
      • A metal's resistance to corrosion is related to its position in the reactivity series.
      • Iron Oxide + Carbon --> Iron + Carbon Dioxide
        • Iron is obtained by the removal of oxygen from Iron Oxide through carbon heating. The iron oxide is reduced to iron.
      • Aluminum Oxide --> Aluminium + Oxygen
    • Recycling Metals
      • Many metals can be recycled. This is when a metal is melted down and made into something new.
      • Natural reserves of metal ores will last longer if metals are recycled.
      • For most metals, less energy is needed to recycle than extract.
        • Recycling aluminium can use just 5% of the energy needed to extract it. This also makes it cheaper.
      • Recycling can reduce the need to mine ores. Mining can damage the landscape and created noise and dust pollution.
      • Recycling produces less pollution.
        • Sulfur Dioxide is formed when lead is extracted, and carbon dioxide is emitted when fossil fuels are used to generate the energy for electrolysis.
      • More recycling means less waste metals are disposed of in landfill sites.
    • Metals and Alloys
      • The uses of metals are related to their properties.
        • Aluminium has a low density. It does not corrode either.
          • It is used to make airplanes, because the lighter the plane the less fuel it needs.
        • Copper is an extremely good electrical conductor and low reactivity with water.
          • Electrical cables are made using copper, and also water pipes.
        • Gold is nonreactive and does not corrode. It is also very attractive.
          • Its main use is jewellery because it an be worked easily into shapes and it does not tarnish.
          • It is also one of the best electrical conductors and is used in printed circuit boards.
        • Iron is very cheap to extract, but is not very strong so is made into steel which is stronger and harder.
          • It is often a mixture of iron and carbon with other materials. It is used to make bridges, cars, electrical goods, machinery and building frames. It is also magnetic.
      • Converting metals into alloys makes them stronger.
        • The new particles jam up the structure of the old atoms so they cannot move and slide over each other as easily.
        • Iron is alloyed with other metals to produce alloy steels with higher strenght and reistance to corrosion.
      • Alloying changes the properties of metals.
        • Shape memory alloys
          • Nitinol is an alloy of nickel and titanium. If the shape of the alloys is changed it returns when heated.
        • Some gold alloys have higher strength,  including fineness and carats which indicate the percentage of pure gold.
      • New materials are developed by chemists to fit new applications.


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Metals, metal ores and alloys resources »