Specification Point 1.57C (Paper 2C Only):
Know that Anion and Cation are terms used to refer to negative and positive ions respectively

Anion & Cation

ANION: Non-metals as they are negative ions and will be attracted to the positive electrode.

Reaction at the Positive Electrode (Anode)

  • Anions (Negative ions) are attracted to the positive electrode.
  • When they get to the electrode, they lose electrons so that they form atoms.

Example: When Lead (II) Bromide is electrolysed, Bromide ions lose an electron to form bromine atoms:

2Br –     –     2e     →     Br2

*Bromine is formed at the anode

CATION: Metals are positive ions and will be attracted to the negative electrode

Reaction at the Negative Electrode (Cathode)

  • Cations (Positive ions) are attracted to the negative electrode.
  • When they get to the electrode, they gain electrons so that they are converted into their atoms.

Example: When Lead (II) Bromide is electrolysed, Lead (II) Ions gain electrons to form Lead Atoms:

Pb2+     +     2e     →     Pb

*Lead is formed at the cathode

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.