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Redox I

Oxidation numbers

  • 4 things to know
  • Papers 1, 2 and 3

Overview

Recall questions on the rules for assigning oxidation numbers, on working them out in ions and compounds, and on what a Roman numeral in a name means.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Numbers

What are the standard rules for assigning oxidation numbers?

Key term

What does a Roman numeral in a name tell you?

Key term

What does an element's oxidation number mean?

Key term

What is the oxidation number of a simple monatomic ion?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What does an element's oxidation number mean?

    Model answer

    The charge an atom would have if all the bonds in the species were treated as fully ionic.

  2. 2

    What is the oxidation number of an atom in an uncombined element?

    Model answer

    Zero.

  3. 3

    What is the oxidation number of a simple monatomic ion?

    Model answer

    Equal to the charge on the ion (e.g. Na⁺ is +1, Cl⁻ is -1).

  4. 4

    What is the usual oxidation number of oxygen, and its exceptions?

    Model answer

    Usually -2; it is -1 in peroxides and +2 in the compound with fluorine (OF₂).

  5. 5

    What is the usual oxidation number of hydrogen, and its exception?

    Model answer

    Usually +1; it is -1 in metal hydrides such as NaH.

  6. 6

    What is the oxidation number of fluorine in its compounds?

    Model answer

    Always -1.

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Atomic Structure and the Periodic Table
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Redox I
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AAtomisation turns each element into gaseous atoms.
BIonisation energy removes electrons from the metal atoms.
CElectron affinity adds electrons to the non-metal atoms.

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Anode means electrode where oxidation occurs.
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