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Group 7(17), the halogens
This topic develops redox and periodic-trend reasoning for halogens and halide ions.
8
Objectives
10
Flashcards
10
Questions
90 min
Study time
AqaA LevelChemistryInorganic chemistry
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Start revising Group 7(17), the halogens
Syllabus checklist
What you need to know
8 objective pages available
Halogen trends and displacement4 objectives
- Describe trends in electronegativity and boiling point down Group 7.
- Explain the trend in oxidising ability of halogens.
- Predict and explain halogen displacement reactions.
- Write ionic equations for halogen displacement reactions.
Halide ions and uses of chlorine4 objectives
- Describe tests for halide ions using silver nitrate and ammonia.
- Explain the use of chlorine in water treatment.
- Explain disproportionation reactions of chlorine in water and alkali.
- Evaluate benefits and risks of chlorine use.
Key terms
ElectronegativityBoiling PointOxidising agentDisplacement ReactionReactivity SeriesIonic EquationSilver NitratePrecipitateDisinfectionHypochloriteDisproportionationChlorination
Exam tips
- Use clear and precise language: When describing trends, use terms like 'increases' or 'decreases' clearly.
- Use correct chemical notation: Always write balanced equations with correct states of matter and charges.
Common mistakes
- Confusing trends in electronegativity and boiling point: Remember that electronegativity decreases down Group 7 due to increased atomic size and shielding.
- Confusing oxidising and reducing agents: Remember that oxidising agents gain electrons and are reduced, while reducing agents lose electrons and are oxidised.
Practice preview
- Which of the following halogens has the highest electronegativity?
- Describe the trend in boiling points of the halogens as you move down Group 7.
- Given that the boiling point of chlorine is -34 °C and bromine is 59 °C, explain why bromine has a higher boiling point than chlorine.
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