Halogens

• Chemistry
• Secondary Education

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Topic 8 - Non-metals

Group VII Elements

25 November 2025

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In this lesson, I will:

• state the appearance of the halogens at r.t.p.
• describe the Group VII halogens: chlorine, bromine and iodine, as diatomic non-metals with general trends in physical and chemical properties down the group.
• predict the properties of other elements in Group VII, given information about the elements.

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Is chlorine dangerous?

Explain, in a sentence, why chlorine is dangerous.

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Work in pairs to answer the following MC questions about halogens.

The Halogens are the elements in Group ________.

1. VIII
2. I
3. III
4. VII

Which of the following is NOT a property of halogens?

1. They are non-metals.
2. They produce coloured vapours.
3. They are diatomic.
4. They have eight electrons in their outer shells.

As we go down Group VII, which of the following general trends DOES NOT happen?

1. The colour increases in intensity.
2. The state goes from solid to liquid to gas.
3. The melting point increases.
4. The boiling point increases.

As we go down Group VII, the reactivity of halogens ______________.

1. decreases
2. increases
3. remains the same
4. never changes

How many electrons in the outer shell do halogens have?

1. 6
2. 1
3. 7
4. 8

The halogens have 7 electrons in their outer shell. They react by _____1______ an electron to complete their outer shell, or by ____2____ electrons with other atoms.

1. 1 - gaining ; 2 - losing
2. 1 - losing ; 2 - gaining
3. 1 - gaining ; 2 - sharing
4. 1 - losing ; 2 - sharing

Halogens react with alkali metals to form _____________ compound.

1. a covalent
2. an ionic
3. a homogeneous
4. a positive

Halogens react with non-metals to form _____________ compound.

1. a covalent
2. an ionic
3. a homogeneous
4. a positive

To determine the reactivity of halogens, a reaction must be carried out. Which of the following is this reaction?

1. thermal decomposition
2. displacement reaction
3. combustion reaction
4. neutralisation reaction

A less reactive halogen can displace a more reactive halogen from an aqueous solution of its halide salts.

1. True
2. False
3. Sometimes

Which of the following describes the reactivity of halogens down Group VII?

1. The reactivity increases.
2. The reactivity decreases.
3. The reactivity remains the same.
4. The reactivity stops.

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Working in groups

- Choose a task card containing command statements about halogens

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Explaining:

Discussion points

• Appearance
• Density 
• Melting point
• Reactivity

Give two things that you learned about 

the properties of Group VII elements.

TEMPLATE

In this lesson, I will:

• state the appearance of the halogens at r.t.p.
• describe the Group VII halogens: chlorine, bromine and iodine, as diatomic non-metals with general trends in physical and chemical properties down the group.
• predict the properties of other elements in Group VII, given information about the elements.

How well did you participate 

in the lesson today?

05

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Assesses student comprehension through a worksheet, quiz, a lab report, or a concluding class discussion.

How well did you enjoy the lesson today?

05

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Topic 8 - Non-metals

Reactivity of Halogens

25 November 2025

How do you feel today?

😒🙁😐🙂😃

TEMPLATE

In this lesson, I will:

• describe the displacement reactions of halogens with other halide ions.
• explain the displacement reactions of halogens with other halide ions.

TEMPLATE

Work in groups:

• Understand the background.
• Read the question.
• Hypothesise.
• Carry out the method to test the hypothesis
• Record results.
• What do the results tell you?
• Formulate a conclusion.