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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