1. What are the properties and trends of Group 7 elements?
All pupils will be able to (Baseline): Describe the trends in properties in Group 7
Most pupils will be able to (Further): Use the displacement reactions to prove the order of reactivity for the halogens is correct
Some pupils will be able to (Challenge): Explain the reactivity of the halogens with reference to their size

2. d2p (2min clip about reactivity and outer shell) Higher Triple explanation, stop at 2min Watch the video and make notes on the properties of the halogens.

3. Will the Fluorine or the Chlorine get the Electron from the Sodium? Why?

4. What did we find out? What is the Order of Reactivity of the Halogens?
Most Reactive
Least Reactive S I Z E R E A C T I V Y
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Astatine (At)

5. The Halogens
The halogens want to grab an electron but it has to get past all the other electrons in the way F Cl Br I As
Group 7 – The Halogens

6. Its all about getting close to the nucleus
Iodine has 53
electrons in the way of its nucleus
Bromine has 35 electrons in the way of its nucleus
Chlorine has 17 electrons in the way of its nucleus
Fluorine has 9 electrons in the way of its nucleus

7. I have learnt that:
The halogens all form ions with a single negative charge in their ionic compounds with metals.
The halogens form covalent compounds by sharing electrons with other non-metals.
A more reactive halogen can displace a less reactive halogen from a solution of one of its salts.
The reactivity of the halogens decreases going down the group.

8. Plenary Questions
Write word and symbol equations for the displacement reactions of:
Potassium Bromide and Chlorine
Sodium Iodide and Fluorine
Would reaction a or b happen the most quickly do you think? Why?
Use ideas about electron configurations to explain the order of reactivity of the halogens.

9. Plenary Questions
Write word and symbol equations for the displacement reactions of:
Potassium Bromide and Chlorine
Sodium Iodide and Fluorine
a) Potassium Bromide + Chlorine Potassium Chloride + Bromine
a) 2KBr + Cl2 2KCL + Br2
b) Sodium Iodide + Fluorine Sodium Fluoride + Iodine
b) 2NaI + F2 2NaF + I2

10. Plenary Questions
Would reaction a or b happen the most quickly do you think? Why?
Reaction b would happen the most quickly. This is because there is a bigger gap between the reactivity of these two Halogens. Therefore Fluorine will displace Iodine more quickly than Chlorine would displace Bromine.

11. Plenary Questions
Use ideas about electron configurations to explain the order of reactivity of the halogens.
The Halogens become less reactive as you go down group 7. This is because to get a full outer shell, the Halogens need to gain an electron. To do this it must attract the electron from another atom. The closer the outer shell is to the nucleus, the more attracted the electron will be to the Halogen.
Therefore large Halogen atoms find it difficult to attract the electron that it needs, and this makes them less reactive. Small Halogen atoms are much more attractive to electrons and react much more vigorously (quickly).