Chemistry for the gifted and talented: oxidation numbers

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This activity introduces oxidation numbers by giving a conceptual foundation for them in terms of electron accounting and polar bonds. It then shows how the model used so far needs refining.

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Oxidation numbers
Handout | PDF, Size 0.27 mb

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Level

16-18 years

Use

Specification

England
- A/AS level
Scotland
- Higher
  - SQA Chemistry
    - 1. Chemical changes and structure
      - (a) Periodicity
        Atoms of different elements have different attractions for bonding electrons. Electronegativity is a measure of the attraction an atom involved in a bond has for the electrons of the bond.
      - (b) Structure and bonding
        (i) Types of chemical bond
        Polar covalent bonds are formed when the attraction of the atoms for the pair of bonding electrons is different. Delta positive (δ+) and delta negative (δ-) notation can be used to indicate the partial charges on atoms, which give rise to a dipole.
Wales
- A/AS level
  - WJEC Chemistry
    - Unit 1: THE LANGUAGE OF CHEMISTRY, STRUCTURE OF MATTER AND SIMPLE REACTIONS
      - 1.1 Formulae and equations
        (b) oxidation numbers of atoms in a compound or ion
      - 1.4 Bonding
        (d) concepts of electronegativity and bond polarity
    - Unit 3: PHYSICAL AND INORGANIC CHEMISTRY
      - 3.2 Redox reactions
        (a) how to construct ion/electron half-equations, for example, for the reduction of acidified Cr₂O₇²⁻ to Cr³⁺ and acidified MnO⁴⁻ to Mn²⁺ and the oxidation of S₂O₃²⁻ to S₄O₆²⁻
        (c) redox reaction between Cu²⁺ and I⁻ and the determination of the liberated iodine with S₂O₃²⁻
Northern Ireland
- A/AS level
  - CCEA Chemistry
    - Unit AS 1: Basic Concepts in Physical and Inorganic Chemistry
      - 1.3 Bonding
        1.3.8 define the term electronegativity and explain the trend in the electronegativity of elements down Groups and across Periods;
        1.3.9 explain that bond polarity arises when covalently bonded atoms have different electronegativities and use partial charges to show that a bond is polar;
      - 1.7 Redox
        1.7.1 calculate the oxidation state for an element in a compound or ion, including peroxides and metal hydrides;
Republic of Ireland
- Leaving Certificate
  - Chemistry
    - 2. Chemical bonding
      - 2.3 Covalent Bonding
        Depth of treatment
        Molecules. Minute size of molecules.
      - 2.4 Electronegativity
        Depth of treatment
        Electronegativity. Periodic variation of electronegativity - explanation for general trends in values: (i) down a group

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