Anions vs Cations

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

Edexcel IGCSE Chemistry Notes

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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.