Edexcel A Level Chemistry

Group 7 Halogens

Group 7 is the p-block mirror of Group 2: the same reasoning about size and shielding, but now the halogens gain electrons instead of losing them. These pages cover the physical trends, the halogens as oxidising agents, the disproportionation reactions of chlorine and the halide ions as reducing agents together with their tests.

Exam Papers

Paper 1

9CH0/01

Specification Points

4.9 – 4.14

6 points covered

Sub-topics

4 lessons

Revision notes available

Exam Board

Edexcel

Pearson 9CH0

Revision Notes

Work through each part of Edexcel Topic 4 in a structured sequence.

F₂ to I₂

Halogen Trends

colour, volatility, electronegativity

Trends in the Halogens

The trends in Group 7: states, colours, boiling points, electronegativity, reactivity and predictions for fluorine and astatine.

Halogens as Oxidising Agents

The halogens as oxidising agents: displacement reactions, colours in water and cyclohexane, reactions with metals and hydrogen, and the reactivity trend.

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Water and bleach

Chlorine Reactions

Cl₂ + H₂O, Cl₂ + NaOH

Disproportionation Reactions of Chlorine

The disproportionation of chlorine with water and with cold and hot alkali, bleach, water treatment and analogous halogen reactions.

Halide Ions: Reducing Agents and Tests

Halide ions: reducing power with concentrated sulfuric acid, the acidified silver nitrate test and ammonia, and the hydrogen halides with ammonia and water.

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Summary map

Download, print and revise the key facts of this topic at a glance.

Summary map · PDF

Halogens Map

Edexcel A Level Chemistry · Topic 4 Inorganic Chemistry and the Periodic Table · Group 7

The whole section on one A4 page: physical trends, displacement, halogens with metals, chlorine disproportionating, halides with H₂SO₄, and halide tests and predictions.

Download the map6 key ideas + a data table · A4 portrait · print ready

Specification Coverage

Group 7 Halogens – Edexcel A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 4.

4B: The elements of Group 7, halogens

4.9

understand reasons for the trends in melting and boiling temperatures, physical state at room temperature, and electronegativity for Group 7 elements

4.10

understand reasons for the trend in reactivity of Group 7 elements down the group

4.11

understand the trend in reactivity of Group 7 elements in terms of the redox reactions of Cl₂, Br₂ and I₂ with halide ions in aqueous solution, followed by the addition of an organic solvent

4.12

understand, in terms of changes in oxidation number, the following reactions of the halogens:

oxidation reactions with Group 1 and 2 metals

the disproportionation reaction of chlorine with water and the use of chlorine in water treatment

iii

the disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide to form bleach

the disproportionation reaction of chlorine with hot alkali

reactions analogous to those specified above

4.13

understand the following reactions:

solid Group 1 halides with concentrated sulfuric acid, to illustrate the trend in reducing ability of the hydrogen halides

precipitation reactions of the aqueous anions Cl^–, Br^– and I^– with aqueous silver nitrate solution, followed by aqueous ammonia solution

iii

hydrogen halides with ammonia and with water, to produce acids

4.14

be able to make predictions about fluorine and astatine and their compounds, in terms of knowledge of trends in halogen chemistry

Specification Coverage

Group 7 Halogens – Edexcel A Level Chemistry

The following specification points outline the knowledge and skills students are expected to demonstrate for Topic 4.

4B: The elements of Group 7, halogens

4.9

understand reasons for the trends in melting and boiling temperatures, physical state at room temperature, and electronegativity for Group 7 elements

4.10

understand reasons for the trend in reactivity of Group 7 elements down the group

4.11

understand the trend in reactivity of Group 7 elements in terms of the redox reactions of Cl₂, Br₂ and I₂ with halide ions in aqueous solution, followed by the addition of an organic solvent

4.12

understand, in terms of changes in oxidation number, the following reactions of the halogens:

oxidation reactions with Group 1 and 2 metals

the disproportionation reaction of chlorine with water and the use of chlorine in water treatment

iii

the disproportionation reaction of chlorine with cold, dilute aqueous sodium hydroxide to form bleach

the disproportionation reaction of chlorine with hot alkali

reactions analogous to those specified above

4.13

understand the following reactions:

solid Group 1 halides with concentrated sulfuric acid, to illustrate the trend in reducing ability of the hydrogen halides

precipitation reactions of the aqueous anions Cl^–, Br^– and I^– with aqueous silver nitrate solution, followed by aqueous ammonia solution

iii

hydrogen halides with ammonia and with water, to produce acids

4.14

be able to make predictions about fluorine and astatine and their compounds, in terms of knowledge of trends in halogen chemistry

Group 7 Halogens

Revision Notes

Summary map

Group 7 Halogens – Edexcel A Level Chemistry

4B: The elements of Group 7, halogens

Group 7 Halogens – Edexcel A Level Chemistry

4B: The elements of Group 7, halogens

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