Group 7 elements – chlorine, bromine and iodine

three of the halogens: chlorine (a green gas), bromine (a orange brown liquid), iodine (a grey solid)

Group 17  ( used to be group 7) contains a  set of non-metals known collectively as The Halogens.

Like many families, the members of Halogen family have a number of similarities to each other. However, they also have some very important differences.


Activity 1. The uses of Chlorine 

Use the internet to find answers to the following questions:
  1. ​What is the single biggest use of chlorine ?
  2. Why is Chlorine used  in water treatment.
  3. What solvents contain chlorine?
  4. What is meant by the term "organics" ?
  5. What is meant by the term " inorganics"?
  6. Whyis chlorine used in the making of pulp and paper?
The main uses of Chlorine

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Activity 2: Ferocious Fluorine 

​This video shows  a range of elements being mixed with fluorine gas. No heat is supplied! Watch each reactions in turn.

  1. Write an equation for each reaction.
  2. Calculate the % mass change which would take place in each reaction. 


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Halogen displacement reactions

This video shows how the reactivity of the halogens changes down the group.

A solution of a halogen ( Cl2 , Br2 or I2 ) is added to a solution of halide (Cl -, Br - , I-). If the halogen is more reactive than the halide it will displace the halide from the solution and there will be a colour change as a result.

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