Oxidation and reduction in terms of electrons

• • When a substance loses electrons it is oxidised
  • When a substance gains electrons it is reduced
  • If this occurs in the same reaction, the reaction is a redox reaction
• Fe → Fe2+ + 2e–

  Cu2+ + 2e–→ Cu

  • The iron has lost electrons to become a positive ion, so has been oxidised
  • The positive copper ion has gained electrons to become an atom, so have been reduced
• • Oxidation and reduction take place during the process of electrolysis at the anode (positive electrode) and the cathode (negative electrode) 
  • Positive ions are attracted towards the cathode
  • Reduction (gain of electrons) takes place here
  • E.g. Pb2+ + 2e– → Pb
  • Negative ions are attracted towards the anode
  • Oxidation (loss of electrons) takes place here
  • E.g. 2Br– → Br2 + 2e–