Alkali metals
Teaching notes
This activity sheet can be used with the set of alkali metal fact cards or other suitable
sources e.g. text books or websites such as www.webelements.com and
http://www.rsc.org/periodic-table . Students could be asked research and create their own
fact cards before being given the activity sheet.
Pupils will need to have been taught atomic structure (for questions one and ten).
Question ten provides more challenge and an opportunity to review electron
configurations.
It encourages pupils of a wide range of abilities to spot patterns in the group and make
predictions.
Answers
1.
Li, Na, K, Rb, Cs, Fr
2.
more
3.
decreases
4.
boiling point decreases
5.
As you go down the group the density increases.
6.
Explosive
7.
a) hydrogen
b) between 1342 0C and 760 0C (actual 883 0C)
c) between 98 0C and 39 0C ( actual 64 0C)
d) below 1.90 g/cm3 (actual density is unknown)
8.
potassium + water  potassium hydroxide + hydrogen
9.
rubidium + water  rubidium hydroxide + hydrogen
10.
Arrangement of electrons in shells
Li – 2, 1
Na – 2,8,1
K – 2,8,8,1
Increase in reactivity as lose outer electron more readily further down the group.
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20043
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Alkali metals
Task
1. On your desk, arrange the fact cards in order of proton number, starting with the lowest
at the top.
2. Choose the word:
As you go down group 1, the metals get more/less reactive.
3. Choose the word:
As you go down group 1, the melting point increases/decreases.
4. Complete the sentence:
As you go down the group, the boiling point ________________
5. Complete the sentence to describe another pattern from the cards:
As you go down the group, ___________________________________
________________________________________________________
6. Draw a picture to show what you think would happen when Rubidium is added to
water.
7. There is information missing from the fact cards. Predict:
a) The gas made when lithium reacts with water
__________________________________________________________
b) The approximate boiling point of sodium
__________________________________________________________
c) The approximate melting point of potassium
__________________________________________________________
d) The approximate density of francium
__________________________________________________________
8. Write an equation for the reaction of potassium with water.
9. Write an equation for the reaction of rubidium with water.
10. Use your knowledge of atomic structure to explain the pattern in reactivity that you
have discovered for this group. It may help you if you draw the electron configurations
for the first three of the elements.
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20043
Page 2 of 3
Alkali metals
Francium
223
87
Caesium
133
Fr
55
Melting point: 290C
Boiling point: 6790C
Density: 1.90g/cm3
0
Melting point: 27 C
Boiling point: 6770C
Density: ____g/cm3
In water: no information - the
element is too rare, radioactive,
and dangerous.
Cs
In water: ______________________
_______________________________
_______________________________ .
caesium + water  _______________________
Lithium
7
3
Rubidium
85
Li
37
Rb
Melting point: 1810C
Boiling point: 13420C
Density: 0.53g/cm3
Melting point: 390C
Boiling point: 6860C
Density: 1.53g/cm3
In water: floats and reacts slowly
with it to produce bubbles of
hydrogen.
In water: ______________________
_______________________________
_______________________________ .
lithium + water  lithium hydroxide + ___________
________________________________________
Potassium
Sodium
39
19
23
K
11
Na
Melting point: ____0C
Boiling point: 7600C
Density: 0.97g/cm3
Melting point: 980C
Boiling point: ____0C
Density: 0.86g/cm3
In water: reacts very quickly to
make hydrogen (which bursts into
flames).
In water: reacts quickly to make
hydrogen. Heat may light hydrogen.
sodium + water  sodium hydroxide + hydrogen
potassium + water  _________ __________ + ________
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20043
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