CIE AS Chemistry (9701) exams from 2022

Revision Notes

1.6.1 Oxidation Number Rules

Oxidation Numbers

  • The oxidation numbers (also known as oxidation state) is a number given to each atom or ion in a compound to keep track of how many electrons they have
  • In a single ion or molecular ion, the oxidation number tells us how many electrons have been lost or gained
  • Positive oxidation number = loss of electrons
  • Negative oxidation number = gain of electrons

Oxidation number rules

  • The oxidation number ( refers to a single atom in a compound

Electrochemistry Table 1_Oxidation Numbers, downloadable AS & A Level Chemistry revision notes

Worked example: Deducing oxidation numbers

Electrochemistry Worked example - Deducing oxidation numbers, downloadable AS & A Level Chemistry revision notes


Electrochemistry Table 2_Oxidation Numbers, downloadable AS & A Level Chemistry revision notes

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Fran has taught A level Chemistry in the UK for over 10 years. As head of science, she used her passion for education to drive improvement for staff and students, supporting them to achieve their full potential. Fran has also co-written science textbooks and worked as an examiner for UK exam boards.

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