Exploring Group 1
Quick Starter
What connects these photos?
show hint
show answer
© HarperCollinsPublishers 2016
Exploring Group 1
Quick Starter
What connects these photos?
X
Where does the
colour in fireworks
come from?
show hint
show answer
© HarperCollinsPublishers 2016
Exploring Group 1
Quick Starter
What connects these photos?
show hint
show answer
© HarperCollinsPublishers 2016
Exploring Group 1
Quick Starter
The connection is salt
Some white salts actually make vibrant colours when placed into a
flame. Alkali metal salts do this
Alkali metals (and some others) are used to make coloured
fireworks. What else are they be used for?
back to question
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Learning questions:
•
•
•
•
•
•
LO
What are the alkali metals?
How do they react with water?
How are they similar?
How are they different?
Why do they react differently?
Why are they similar?
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend,
electronic structure
© HarperCollinsPublishers 2016
What are the alkali metals?
NK
• Alkali metals are all found in group 1 of the
periodic table.
• Why are they all in the same group?
• What does this tell you about their electronic
structure?
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend,
electronic structure
© HarperCollinsPublishers 2016
What are the alkali metals like?
Colour
Element
Hard?
Does it
tarnish?
Electrical
conductivity
CM
m.p.
(°C)
b.p.
(°C)
Density
(g/cm3)
lithium
Li
181
1347
0.53
sodium
Na
98
883
0.97
potassium
K
64
774
0.86
rubidium
Rb
silvery
white
very
soft
very fast
good
39
688
1.53
caesium
Cs
silvery
gold
very
soft
very fast
good
29
678
1.87
francium
Fr
What pattern do you notice?
Why does this happen?
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Alkali metals with water
Observation
lithium
sodium
CM
potassium
1. Floats on water
2. Moves around water
3. Makes a hissing noise
4. Melts, making a sphere
5. Leaves a trail in the water
6. Universal indicator turns
mauve (alkali formed)
7. Bubbles of gas appear
where metal touches water
8. Gas catches fire by itself
9. Coloured sparks/flame
10. Sharp crackle at end of
reaction
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Alkali metals with water
Observation
CM
lithium
sodium
potassium
1. Floats on water
yes
yes
yes
2. Moves around water
yes
yes
yes
3. Makes a hissing noise
yes
yes
yes
4. Melts, making a sphere
no
yes
yes
5. Leaves a trail in the water
yes
yes
yes
6. Universal indicator turns
yes
yes
yes
yes
yes
yes
no
if metal is
trapped
yes
9. Coloured sparks/flame
Gas burns with
red flame if lit
yellow
lilac
10. Sharp crackle at end of
no
yes
yes
mauve (alkali formed)
7. Bubbles of gas appear
where metal touches water
8. Gas catches fire by itself
reaction
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Alkali metals with water
ATD
• What patterns do you notice about as you look
down group 1?
• What would you expect to see if you reacted
rubidium and caesium with water?
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Alkali metals with water
Element
What would happen
(prediction):
rubidium
Rb
caesium
Cs
ATD
What actually happens
(video):
https://www.youtube.com/watch?v=uixxJtJPV
Xk
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Alkali metals with water
CM
Sodium + water  sodium hydroxide + hydrogen
2Na + 2H20  2NaOH + H2
Lithium + water  lithium hydroxide + hydrogen
2Li
+ 2H20  2LiOH + H2
Potassium + water  potassium hydroxide + hydrogen
2K + 2H20  2KOH + H2
How could we test that
the gas is hydrogen?
What makes the
solution an alkali?
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
ATD
Why do the alkali metals react differently?
• When the group 1 metals react they lose their
outer electron, which of the metals will lose this
electron easiest? Why? What is this called?
• Draw out the electronic structures of the first 3
alkali metals. Use this to explain why potassium
is most reactive.
• (remember the alkali metals want to lose 1
electron)
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
ATD
Why do the alkali metals react differently?
• As the atom becomes bigger and bigger the
electron in the outer shell is held less tightly and is
more likely to escape.
• We say that the outer electron has been shielded
from the positive nucleus, so less attraction.
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure
Why do the alkali metals react
differently?
R
1. Explain why the alkali metals are more
reactive as you go down the group.
2. Describe the reactions of alkali metals with
water.
3. Explain why the alkali metals are stored in oil.
Keywords:
Group 1, alkali metal, oxidation, reduction, sheilding, electrons, density, trend, electronic
© HarperCollinsPublishers 2016
structure