Redox Reactions

• Oxidation


  When a metal reacts with oxygen, the metal has gained oxygen
• Reduction


  When oxygen is removed from a metal compound, the metal atoms have lost oxygen
• Reaction of metals with oxygen


  1. Metal forms metal oxide

  2. Oxidation reaction takes place
• Reactions of metals with oxygen


  • Magnesium reacting with oxygen
  • Iron reacting with oxygen
• Magnesium reacting with oxygen


  Magnesium is oxidized, it gains oxygen
• Iron reacting with oxygen


  Iron is oxidized, it gains oxygen
• Magnesium oxide being split into magnesium and oxygen


  Magnesium is reduced, it loses oxygen
• Calcium reacting with copper oxide


  • Calcium is oxidized, it gains oxygen
  • Copper is reduced, it loses oxygen
• Reactions of metals with oxygen and oxidation/reduction will be explored in more videos
• Oxidation


  Loss of electrons
• Reduction


  Gain of electrons
• Magnesium atom forming magnesium ion Mg2+


  1. Magnesium atom loses electrons

  2. Magnesium atom is oxidized
• Sulfur atom forming sulfide ion

  1. Sulfur atom gains electrons

  2. Sulfur atom is reduced
• Aluminium atom forming aluminium ion


  1. Aluminium atom loses 3 electrons

  2. Aluminium atom is oxidized
• Oxygen atom forming oxide ion

  1. Oxygen atom gains 2 electrons

  2. Oxygen atom is reduced
• Zinc reacting with copper sulfate


  • Zinc is oxidized
  • Copper is reduced
• Half equations show oxidation and reduction of individual atoms/ions
• Symbol equations show overall oxidation and reduction in a reaction