Metal oxides

• • Metals react with oxygen in the air to produce metal oxides
• • Oxidation is a reaction in which:
  • Oxygen is added to an element or a compound
• • Reduction is a reaction in which:
  • Oxygen is removed from an element or a compound
• • A common example of oxidation is the reaction with red-brown copper metal to produce black copper oxide:

  2Cu + O2 ⟶ 2CuO

  • In this reaction copper metal has been oxidised since oxygen has been added to it
• • Another example is the reaction of zinc oxide with carbon:

  ZnO + C ⟶ Zn + CO

  • In this reaction the zinc oxide has been reduced since it has lost oxygen. The carbon atom has been oxidised since it has gained oxygen. 
• Redox reactions are simultaneous Because any loss of electrons by one substance must be accompanied by a gain in electrons by another su , oxidation and reduction always occur together
• A redox reaction is when oxidation and reduction happen at the same time