1. The Periodic Table (Part 2)
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The Periodic Table (Part 2)
WJEC GCSE Applied Science
Our Planet : Obtaining Resources

2. Lesson Objectives By the end of this lesson you should:
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By the end of this lesson you should:
Be able to identify the alkali metals and the halogens in The Periodic Table
Be able to write equations for the reactions of the alkali metals and the halogens.

3. Group 1 – The alkali metals
13/09/2018 Li Na K Rb Cs Fr

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5. Flame tests
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Compounds containing lithium, sodium and potassium can be recognised by burning the compound and observing the colours produced:
Lithium
Red
Sodium
Yellow
Potassium
Lilac

6. Reactions with water
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7. Group 1 – The alkali metals
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Some facts…
1) These metals all have ___ electron in their outer shell
2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily.
3) They all react with water to form an alkali (hence their name) and __________, e.g:
Potassium + water potassium hydroxide + hydrogen
2K(s) H2O(l) KOH(aq) H2(g)
Words – down, one, shell, hydrogen, nucleus

8. Group 7 – The Halogens
13/09/2018 F Cl Br I At

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10. Reactions of halogens
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11. Group 7 – The Halogens Decreasing reactivity Some facts…
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Decreasing
reactivity
Some facts…
1) Reactivity DECREASES as you go down the group
2) At room temperature chlorine is a green gas, bromine is an orange liquid and iodine is a grey solid
3) Chlorine is used to sterilise water while iodine is used to sterilise wounds
4) Melting point, boiling point and density all increase going down the group
5) Reactions with group 1 metals:
metal+ halogen metal halide
sodium + chlorine sodium chloride

12. 13/09/2018
Plenary
A technician found that the labels had come off bottles containing the alkali metals lithium, sodium and potassium. Describe a simple test she could carry out to identify the metals. Give a safety precaution she must take and describe the expected observations for each metal.