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 ID: 577148
Download Presentation The PPT/PDF document "What are the properties and trends of Gr..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
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 sizeSlide2
http://www.bbc.co.uk/education/clips/zm94d2p
(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.Slide3
Will the Fluorine or the Chlorine get the Electron from the Sodium?
Why?
Chlorine
FluorineSlide4
What did we find out?
What is the Order of Reactivity of the Halogens?
Fluorine (F)
Chlorine (Cl)
Bromine (Br)
Iodine (I)
Astatine (At)
S
I
Z
E
Most Reactive
Least Reactive
R
E
A
C
T
I
V
I
T
YSlide5
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 HalogensSlide6
Its all about getting close to the nucleus
Fluorine has 9 electrons in the way of its nucleus
Chlorine has 17 electrons in the way of its nucleus
Bromine has 35 electrons in the way of its nucleus
Iodine has 53
electrons in the way of its nucleusSlide7
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.Slide8
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.Slide9
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 + Brominea)
2KBr + Cl2 2KCL + Br2
b) Sodium Iodide + Fluorine Sodium Fluoride + Iodineb)
2NaI + F2 2NaF + I2Slide10
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.Slide11
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).