Year 11 - Science
Reactions of the halogens: including displacement practical
Groups of the periodic table
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores how elements' reactions are related to electron arrangement and atomic number. It covers the properties of Groups 1, 7, and 0 and explains how these depend on outer electrons. It also predicts element reactivity and reactions based on their positions in the periodic table.
Lesson Summary
You will learn to write word and symbol equations to show how Group 7 elements react.
Key Notes
- Halogens can be dissolved in water to form acidic solutions.
- A more reactive halogen can displace a less reactive one from a compound.
- Group 7 elements react with Group 1 and 2 metals to form salts.
- The chemical test for chlorine involves passing the gas over damp blue litmus paper.
Vocabulary To Learn
- displacement: reaction is where a more reactive element replaces a less reactive element in a compound.
- solution: is formed when a substance dissolves in a liquid.
- halides: are the name of salts formed from halogens, e.g. sodium chloride (NaCl).
Common Mistakes To Avoid
- Halogen solutions are coloured and sometimes it can be difficult to determine colour changes during displacement reactions.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Halogens can be dissolved in water to form acidic solutions. A more reactive halogen can displace a less reactive one from a compound.
2. Define this scientific word and use it in context. 'displacement'
reaction is where a more reactive element replaces a less reactive element in a compound. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Halogen solutions are coloured and sometimes it can be difficult to determine colour changes during displacement reactions. Correction: Displacement of iodine gives the darkest colour change (turns brown), while bromine will provide one which is lighter (turns orange).
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