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Group 7: the halogens

Edexcel IGCSE Chemistry

Topic questions Atomic structure and the periodic table Group 7: the halogens

Group 7: the halogens

13 questions · 128 marks · about 2.5 hours

Group 7: the halogens questions

TopicGroup 7: the halogens

Chemistry Paper 2 November 2023, Question 1 6 marks

This question is about Group 7, the halogens.

(a)

What is the total number of electrons in one fluorine atom?

$Question 1, shown as an image$

[1]

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(b)

What is the charge on a bromide ion?

$Question 1, shown as an image$

[1]

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(c)

Which of these describes the element iodine at room temperature?

$Question 1, shown as an image$

[1]

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(d)

When a halogen is added to a solution containing halide ions, a displacement reaction may occur.

The table shows whether a reaction occurs.

Halogen added	Chloride ion Bromide ion in solution in solution	Iodide ion in solution
chlorine	reaction	reaction
bromine	no reaction	reaction
iodine	no reaction no reaction

Using information from the table, explain the order of reactivity of the three halogens.

[3]

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Chemistry Paper 1 June 2023, Question 7 14 marks

This question is about the three halogens, bromine, chlorine and iodine.

(a)

Give the number of protons and the number of neutrons in an atom of iodine–127

number of protons

number of neutrons

[2]

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(b)

A sample of bromine contains two isotopes.

• Br–79 with relative abundance 52.8 %

• Br–81 with relative abundance 47.2 %

Calculate the relative atomic mass (A_r) of this sample of bromine.

Give your answer to three significant figures.

[3]

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(c)

Aluminium reacts with chlorine to form aluminium chloride.

This is the equation for the reaction.

$Question 7, shown as an image$

Calculate the minimum mass of chlorine needed to form 26.7 g of aluminium chloride.

[for Cl₂, M_r = 71 for AlCl₃, M_r = 133.5]

[3]

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(d)

A student mixes the following pairs of solutions.

Pair 1 bromine solution and potassium chloride solution

Pair 2 bromine solution and potassium iodide solution

Explain how the student can use the results of these experiments to show the order of reactivity of the three halogens, bromine, chlorine and iodine.

Include observations in your answer.

[6]

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Chemistry Paper 2 June 2023 (R), Question 2 7 marks

The table gives some information about the halogens, fluorine, chlorine, bromine and iodine.

Halogen	room temperaturePhysical state at Colour Colour of dilute aqueous solution of halogen
fluorine	gas colourless
chlorine	gas green colourless
bromine	red‑brown orange
iodine	solid grey brown

(a)

Complete the table by giving the missing information.

[2]

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(b)

Describe a test to show that a colourless liquid is an alkene.

[2]

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(c)

A student is given an aqueous solution of chlorine and an aqueous solution of sodium iodide.

The student mixes the two solutions.

Explain the colour change that occurs.

[3]

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Chemistry Paper 1 January 2023 (R), Question 6 11 marks

This question is about elements in Group 7 of the Periodic Table.

(a)(i)

Which element is a liquid at room temperature?

$Question 6, shown as an image$

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(a)(ii)

What colour is solid iodine?

$Question 6, shown as an image$

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(a)(iii)

Describe a test for chlorine gas.

[2]

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(b)

A sample of chlorine, containing two isotopes, has this percentage composition by mass.

chlorine‑35 71.2% chlorine‑37 28.8%

Calculate the relative atomic mass of this sample of chlorine.

Give your answer to one decimal place.

[3]

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(c)

A student is given an aqueous solution of chlorine and an aqueous solution of sodium iodide.

Explain how the student can use these solutions to compare the reactivity of chlorine with the reactivity of iodine.

[4]

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Chemistry Paper 2 June 2022, Question 3 12 marks

This question is about Group 7, the halogens.

(a)

Which halogen has the palest colour?

$Question 3, shown as an image$

[1]

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(b)

Which halogen is a solid at room temperature?

$Question 3, shown as an image$

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(c)

The table shows the electronic configurations of a fluorine atom and a chlorine atom.

	Electronic configuration
fluorine	2.7
chlorine	2.8.7

Explain the relative reactivities of fluorine and chlorine using the information in the table.

[4]

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(d)

Lithium reacts with chlorine to form lithium chloride.

(d)(i)

Write a chemical equation for the reaction of lithium with chlorine.

[1]

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(d)(ii)

Describe tests to show that the product of the reaction is lithium chloride.

[5]

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Chemistry Paper 2 November 2021, Question 1 5 marks

Use the Periodic Table to help you answer this question.

(a)

Identify the element with atomic number 7

[1]

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(b)

Identify a solid non‑metallic element in Period 3

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(c)

Name an element in Group 7 that is a liquid at room temperature.

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(d)

State the relative atomic mass of the element that is in Group 4 and Period 4

[1]

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(e)

Which row shows the most reactive element in Group 1 and Group 7?

[1]

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Chemistry Paper 2 January 2021 (R), Question 2 9 marks

Also involves Electronic structure

This question is about elements in Group 7 and their compounds.

The table gives information about some of these elements.

Element	Symbol	Melting point in °C	Boiling point in °C	Colour at room temperature (20 °C)
fluorine	F	–220	–188
chlorine	Cl	–101	–35	pale green
bromine	Br	–7	59	red‑brown
iodine	I	114	184	grey

(a)(i)

Predict the colour of fluorine at room temperature.

[1]

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(a)(ii)

How many of the elements in the table are liquids at room temperature (20 maths symbol C)?

$Question 2, shown as an image$

[1]

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(a)(iii)

The element astatine is below iodine in Group 7.

Predict the formula of a molecule of astatine.

[1]

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(b)

Sea water contains bromide ions.

Bromine can be obtained by bubbling chlorine through a sample of sea water.

The ionic equation for the reaction is

$Question 2, shown as an image$

(b)(i)

Explain which species acts as an oxidising agent in this reaction.

[2]

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(b)(ii)

The reaction occurs because chlorine is more reactive than bromine.

Bromine is below chlorine in Group 7.

Explain the decrease in reactivity from chlorine to bromine.

[3]

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(c)

Elements in Group 7 react with elements in Group 1 to form ionic compounds.

Which pair of ions both have the electronic configuration 2.8.8?

$Question 2, shown as an image$

[1]

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Chemistry Paper 1 November 2020 (R), Question 2 5 marks

The diagram shows the positions of some elements in the Periodic Table.

1 2 3 4 5 6 7 0

$Question 2, shown as an image$

(a)

Use symbols from this table to answer these questions.

Each symbol may be used once, more than once or not at all.

(a)(i)

Give the symbol of a metal.

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(a)(ii)

Give the symbol of a noble gas.

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(a)(iii)

Give the symbol of a liquid at room temperature.

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(a)(iv)

Give the symbols of the two elements in Period 3

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(b)

Deduce the electronic configuration of Na

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Chemistry Paper 1 November 2020 (R), Question 6 13 marks

This question is about elements in Group 7 of the Periodic Table and their compounds.

(a)(i)

Give the name of this group of elements.

[1]

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(a)(ii)

State the colour of chlorine gas.

[1]

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(a)(iii)

Give a test for chlorine gas.

[2]

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(b)

Give a test to show that a solution contains iodide ions.

[3]

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(c)

A student compares the reactivity of the elements bromine, chlorine and iodine.

He mixes these pairs of solutions and observes the reactions that occur.

• chlorine solution and potassium bromide solution

• bromine solution and potassium iodide solution

Explain how the reactions can be used to show the order of reactivity of the three elements.

Include the colour change that the student would observe in each reaction.

[6]

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Chemistry Paper 1 January 2020 (R), Question 3 9 marks

Also involves Hazard symbols and risk assessment

The Group 7 elements are called halogens.

Halogens form compounds called halides.

Three of the halogens are represented by the formulae X₂, Y₂ and Z₂

Solutions of these halogens are added separately to solutions of sodium halides, NaX, NaY and NaZ.

The table shows whether or not a reaction occurs.

	X₂	Y₂	Z₂
NaX	no	yes	yes
NaY	no	no	yes
NaZ	no	no	no

(a)

Use the information in the table to deduce the order of reactivity of the halogens X₂, Y₂ and Z₂

[1]

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(b)

An aqueous solution of halogen Y₂ is orange.

This solution is decolourised when it reacts with an alkene.

Deduce the identity of halogen Y₂

[1]

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(c)(i)

The table shows some physical properties of the halogens.

Complete the table by predicting a boiling point for chlorine, the state of fluorine at room temperature and the colour of astatine.

Halogen	Boiling point in °C	State at room temperature	Colour
fluorine	−188		yellow
chlorine		gas	green
bromine	59	liquid	red-brown
iodine	sublimes	solid	grey
astatine	337	solid

[3]

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(c)(ii)

Why do the halogens have similar chemical properties?

$Question 3, shown as an image$

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(d)

A teacher uses this apparatus to demonstrate the reaction between chlorine gas and iron wool. The teacher does the reaction in a fume cupboard.

(d)(i)

Suggest why the teacher does the reaction in a fume cupboard.

[1]

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(d)(ii)

The product of the reaction between iron and chlorine is iron(III) chloride.

The ions in iron(III) chloride are Fe³⁺ and Cl⁻

Use this information to give the chemical equation for this reaction.

[2]

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Chemistry Paper 1 January 2020, Question 7 13 marks

This question is about some of the halogens and their compounds.

(a)(i)

Which element is a liquid at room temperature?

$Question 7, shown as an image$

[1]

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(a)(ii)

Which element has the palest colour?

$Question 7, shown as an image$

[1]

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(a)(iii)

Which element is the least reactive?

$Question 7, shown as an image$

[1]

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(b)

A teacher uses displacement reactions to demonstrate the reactivities of some halogens.

She adds solutions of chlorine, bromine and iodine separately to three different sodium halide solutions.

The table shows some of the teacher’s results.

	sodium chloride	sodium bromide	sodium iodide
chlorine solution	not done	solution turns orange
bromine solution	solution stays orange	not done	solution turns brown
iodine solution		solution stays brown	not done

A change in colour of the solution indicates that a reaction has occurred.

(b)(i)

Complete the table by predicting the missing results.

[2]

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(b)(ii)

State why the teacher does not add bromine solution to sodium bromide solution.

[1]

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(b)(iii)

The word equation for the reaction of bromine with sodium iodide is

bromine + sodium iodide maths symbol iodine + sodium bromide

Write a chemical equation for this reaction.

[1]

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(c)

A technician sees an unlabelled bottle containing a liquid.

He knows that the liquid is a solution of one of these compounds.

● copper(II) chloride

● copper(II) bromide

● iron(II) chloride

● iron(II) bromide

Describe chemical tests that the technician could use to identify the compound in the solution.

[6]

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Chemistry Paper 2 June 2019, Question 2 9 marks

The table gives some information about the halogens, chlorine, bromine and iodine.

Halogen	Physical state at room temperature	Colour
chlorine	gas	pale green
bromine		red-brown
iodine	solid

(a)

Complete the table.

[2]

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(b)

Chlorine has two isotopes of mass numbers 35 and 37

The relative percentage of each isotope in a sample of chlorine is

chlorine-35 77.78% chlorine-37 22.22%

Calculate the relative atomic mass of this sample of chlorine.

Give your answer to one decimal place.

[3]

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(c)

A student is given an aqueous solution of chlorine and an aqueous solution of potassium bromide.

Explain how he can use these two solutions to compare the reactivity of chlorine with the reactivity of bromine.

[4]

Chemistry Paper 2 June 2019 (R), Question 4 15 marks

Also involves Covalent bonding

This question is about the halogens and their compounds.

(a)

The table gives the colour and physical state at room temperature of the halogens.

Complete the table by predicting the colour of astatine and the physical state of fluorine at room temperature.

Halogen	Colour	Physical state at room temperature
fluorine	pale yellow
chlorine	pale green	gas
bromine	red‑brown	liquid
iodine	dark grey	solid
astatine		solid

[2]

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(b)

Chlorine gas is bubbled into a colourless solution of potassium bromide.

Explain why the solution turns orange.

[2]

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(c)

Potassium bromide is an ionic compound.

Draw diagrams to show the outer electrons in a potassium ion and in a bromide ion.

Include the charges on the ions.

[3]

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(d)

A student sets up a circuit to test the electrical conductivity of water, solid sodium chloride and aqueous sodium chloride.

The table shows the student’s results.

Substance	Conducts electricity?
water	no
solid sodium chloride	no
aqueous sodium chloride	yes

Explain these results, with reference to the structure and bonding of the substances.

[5]

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(e)

A concentrated aqueous solution of sodium chloride is electrolysed using graphite electrodes.

Chlorine is formed at the positive electrode (anode).

(e)(i)

Give an ionic half‑equation for the formation of chlorine at the positive electrode.

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(e)(ii)

State why this ionic half‑equation represents an oxidation reaction.

[1]

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(e)(iii)

Which substance is formed at the negative electrode (cathode)?

$Question 4, shown as an image$

[1]

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