Group 7 (halogens)
Overview
The halogens sit in Group 7 of the periodic table and include some of the most recognisable non-metals in chemistry. Chlorine disinfects swimming pools, bromine is one of only two elements that are liquid at room temperature, and iodine is the dark solid used to test for starch. Despite looking very different, all halogens share a pattern of chemical behaviour because they each have seven electrons in their outer shell.
In this lesson you will learn the physical properties and trends across Group 7, explore how displacement reactions reveal the reactivity trend, and practise predicting the properties of halogens you may not have met.
Objectives
- Know the colours, physical states (at room temperature) and trends in physical properties of these elements
- Use knowledge of trends in Group 7 to predict the properties of other halogens
- Understand how displacement reactions involving halogens and halides provide evidence for the trend in reactivity in Group 7
Mind map
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Flashcards
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Group 7 (halogens). Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- What is the physical state of bromine at room temperature? A) Solid B) Liquid C) Gas D) Plasma Answer: B
- Which halogen is the most reactive? A) Iodine B) Bromine C) Chlorine D) Fluorine Answer: D
- What colour change is seen when chlorine water is added to potassium bromide solution? A) Colourless to brown B) Colourless to orange C) Orange to colourless D) Brown to colourless Answer: B
- Why does reactivity decrease down Group 7? A) The atoms lose electrons more easily B) The atoms have fewer electrons in their outer shell C) The outer shell is further from the nucleus, weakening the attraction for incoming electrons D) The atoms become smaller Answer: C
- Which of the following displacement reactions would NOT occur? A) Chlorine added to potassium iodide B) Bromine added to potassium iodide C) Iodine added to potassium bromide D) Chlorine added to potassium bromide Answer: C
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