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AQA A Level Chemistry

3.2.3
Group 7 (17)

Section 3.2.3 covers the trends in electronegativity and boiling point of the halogens, their oxidising ability shown by displacement reactions, the reducing ability of the halide ions shown by their reactions with concentrated sulfuric acid, the acidified silver nitrate test and the ammonia follow-up, and the reactions of chlorine with water and with cold dilute sodium hydroxide, including the use of chlorine in water treatment.

Exam Paper
Paper 1 & 3
7405/1 and 7405/3
Specification Points
3.2.3.1 – 3.2.3.2
12 statements
Sub-topics
4 lessons
Revision notes available
Exam Board
AQA
7405 (2015 onwards)

Revision Notes

4 revision notes, in the order the specification teaches them.

Three jars of halogens: gas, liquid and solid
1

Trends in the Halogens

The trends in Group 7 (17): states, colours, boiling points, electronegativity, reactivity and predictions for fluorine and astatine.

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Three tubes of halogen colours in pale, orange and brown
2

Halogens as Oxidising Agents

The halogens as oxidising agents: displacement reactions, colours in water and cyclohexane, reactions with metals and hydrogen, and the reactivity trend.

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Chlorine gas bubbling into water beside a bleach bottle
3

Disproportionation Reactions of Chlorine

The disproportionation of chlorine with water and with cold and hot alkali, bleach, water treatment and analogous halogen reactions.

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Three tubes of white, cream and yellow precipitates
4

Halide Ions: Reducing Agents and Tests

Halide ions: reducing power with concentrated sulfuric acid, the acidified silver nitrate test and ammonia, and the hydrogen halides with ammonia and water.

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Summary Map

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Summary map

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Illustration of a summary map: compounds joined by reaction arrows
Summary map · PDF

Halogens Map

AQA A-level Chemistry · 3.2.3 Group 7(17), the halogens

The whole section on one A4 page: physical trends, displacement, chlorine in water, chlorine disproportionating, halides with H₂SO₄, and silver nitrate tests.

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3.2.3.1

  1. i

    explain the trend in electronegativity of the halogens down the group

    Revise
  2. ii

    explain the trend in boiling point of the halogens in terms of their structure and bonding

    Revise
  3. iii a

    describe the trend in oxidising ability of the halogens down the group

    Revise
  4. iii b

    explain the trend in oxidising ability of the halogens down the group

    Revise
  5. iii c

    describe displacement reactions of halide ions in aqueous solution

    Revise
  6. iii d

    explain displacement reactions of halide ions in aqueous solution

    Revise
  7. iv a

    describe the trend in reducing ability of the halide ions

    Revise
  8. iv b

    explain the trend in reducing ability of the halide ions

    Revise
  9. iv c

    describe the reactions of solid sodium halides with concentrated sulfuric acid

    Revise
  10. iv d

    explain the reactions of solid sodium halides with concentrated sulfuric acid

    Revise
  11. v

    know the use of acidified silver nitrate solution to identify and distinguish between halide ions

    Revise
  12. vi

    know the trend in solubility of the silver halides in ammonia

    Revise
  13. vii a

    explain why silver nitrate solution is used to identify halide ions

    Revise
  14. vii b

    explain why silver nitrate solution is acidified when identifying halide ions

    Revise
  15. vii c

    explain why ammonia solution is added when identifying halide ions

    Revise

3.2.3.2

  1. i a

    know the reaction of chlorine with water to form chloride ions

    Revise
  2. i b

    know the reaction of chlorine with water to form chlorate(I) ions

    Revise
  3. ii

    know the reaction of chlorine with water to form chloride ions and oxygen

    Revise
  4. iii

    know the use of chlorine in water treatment and appreciate that the benefits to health outweigh its toxic effects

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  5. iv

    appreciate that society assesses the advantages and disadvantages when deciding if chemicals should be added to water supplies

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  6. v a

    know the reaction of chlorine with cold, dilute, aqueous NaOH

    Revise
  7. v b

    know the uses of the solution formed when chlorine reacts with cold, dilute, aqueous NaOH

    Revise