8.3 REACTIONS OF METALS AND OXYGEN

• Reactive


  most metals react w/ oxygen when hot enough but some are more reactive eg. magnesium is more reactive than iron.

  some react without being heated
• Dull or Shiny

  when pieces of sodium, potassium or calcium are taken from their containers, they appear dull. when pieces are cut they appear shiny.
• Oxidation


  the shiny surface soon becomes dull bc the metal reacts w/ the oxygen in the air.

  metal + oxygen -> metal oxide
• Prevention


  metals are covered with a new substance - the oxide, and are so reactive they must be stored under oil to prevent a reaction with water vapour in the air.
• Inert


  metals that do not react with oxygen which are generally unreactive
• Rusting Word Equation


  when iron is left in damp air it rusts

  iron + oxygen -> iron oxide
• Rusting


  iron changes and no longer has the same properties. buildings could even collapse. this happens when water and oxygen are present. takes long as iron is not very reactive with oxygen.
• Rust Prevention

  1. no air
  2. painted to stop oxygen
  3. galvanised (covered in zinc to stop oxygen)