Reactivity of Group 7 halogens

Question 1

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What makes halogens oxidising agents?

Answer 1

When they react, they remove an electron from another species causing the other species to be reduced

Question 2

Give the ionic equation of the REDOX reaction between a halogen e.g. Cl<sub>2</sub> and another species (X)

Answer 2

Cl<sub>2</sub> + 2X<sup>-</sup>→2Cl<sup>-</sup> + 2X

Question 3

The more [blank] the halogen, the more powerful an [blank] it is

fill in the blank

Answer 3

• reactive
• oxidising agent

Question 4

What happens to the reactivity of halogens going down the group?

Answer 4

It decreases

Question 5

Explain why the reactivity of halogens decreases going down group 7

Answer 5

• As you go down group 7, the atomic radius increases, this increases the distance between the nucleus and the outer electrons
• The number of inner shells increases which increases the electron shielding
• This decreases the nuclear attraction between the nucleus and the outer shell electrons and so more energy is required to gain an electron from a different species
• So the reactivity decreases and they become weaker oxidising agents.

Question 6

Give the half equation for a halogen e.g. Cl<sub>2</sub>

Answer 6

Cl<sub>2</sub> + 2e→2Cl<sup>-</sup>

Question 7

What is a disproportionation reaction?

Answer 7

A reaction where the atoms of the same element are both reduced AND oxidised

Question 8

What does the reaction between water and chlorine do?

Answer 8

purifies water

Question 9

Give a benefit and two risks of using chlorine to purify water

Answer 9

• • Kills bacteria
• • Produces chlorinated hydrocarbons
• -Produces toxic compounds

Question 10

What does chlorine react with to form bleach?

Answer 10

Cold dilute aqueous sodium hydroxide