Metal Oxides (AQA GCSE Chemistry: Combined Science)

• Metals react with oxygen in the air to produce metal oxides
• Oxidation and reduction involve the addition or removal of oxygen from a substance and are called redox reactions
• 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 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.