Teaching notes
Slides 3 – 11
The section takes students through the limestone cycle by making model compounds. The
models don’t distinguish between ionic and covalent bonds, different coloured bond pieces
could be used to show ionic and covalent bonds if appropriate for the group.
Students could work in pairs or independently.
Each pair will need the following Molymod pieces.
The limestone cycle
-
I x calcium atom
2 x carbon atoms
6 x oxygen atoms
2 x hydrogen atoms
12 x bonds
Click the boxes on each slide to reveal what the model compounds should look like.
Slide 12 – 17
Check students knowledge of the cycle using the interactive quiz. Depending on the group
you can choose to reveal multiple choice options if and when it’s appropriate.
© www.teachitscience.co.uk 2013
21076
1
calcium
carbonate
add CO2
21076
2
Make a model of limestone (calcium carbonate)
using the Molymod atoms.
heat
The
limestone
cycle
calcium
hydroxide
solution
© www.teachitscience.co.uk 2013
CaCO3
calcium
oxide
O
filter
add water
calcium
hydroxide
© www.teachitscience.co.uk 2013
O
C
Ca
Answer
O
21076
3
© www.teachitscience.co.uk 2013
When calcium carbonate is heated it breaks down to form calcium
oxide and carbon dioxide. This is called thermal decomposition.
add CO2
Task
21076
calcium
carbonate
4
heat
Break down your calcium carbonate model to make
calcium oxide and carbon dioxide.
heat
CaCO3
CaO
Ca
© www.teachitscience.co.uk 2013
O
O
21076
calcium
hydroxide
solution
CO2
C
filter
O
5
© www.teachitscience.co.uk 2013
The
limestone
cycle
calcium
hydroxide
21076
calcium
oxide
add water
6
1
Task
When calcium oxide is added to water it forms calcium hydroxide.
Combine your models of calcium oxide and water together
to make calcium hydroxide.
calcium hydroxide
H
CaO
O
water
calcium oxide
H
O
H
O
H
Ca
O
H
O
H
Ca(OH)2
Ca
© www.teachitscience.co.uk 2013
21076
7
© www.teachitscience.co.uk 2013
21076
8
Task
calcium
carbonate
add CO2
calcium
hydroxide
solution
The
limestone
cycle
filter
calcium
hydroxide
© www.teachitscience.co.uk 2013
If carbon dioxide is bubbled through calcium hydroxide solution (limewater)
It turns milky because calcium carbonate is formed.
Combine your models of calcium hydroxide and carbon dioxide
to form calcium carbonate.
heat
O
0
0
add water
9
O
© www.teachitscience.co.uk 2013
add CO2
Ca
21076
calcium
carbonate
10
heat
Ca
C
O
calcium
hydroxide
solution
Task
H
Which atoms are left over?
OAnswer
Which compound can you make
from them?
© www.teachitscience.co.uk 2013
C
CaCO
3
O
21076
Limestone!
CO2
Ca(OH)2
calcium
oxide
21076
filter
H
11
© www.teachitscience.co.uk 2013
The
limestone
cycle
calcium
hydroxide
21076
calcium
oxide
add water
12
2
addtoCO
Click
reveal
2
calcium
hydroxide
Click
to reveal
solution
calcium
carbonate
What is the chemical name for
limestone?
Click to reveal
Clickheat
to reveal
The
limestone
cycle
calcium
oxide
A: carbon malagnite
Click to reveal
B: calcium carbonate
Clickfilter
to reveal
calcium
hydroxide
C: calcium oxide
addtowater
Click
reveal
Click for multiple choice
Click to reveal
© www.teachitscience.co.uk 2013
D: calcium hydroxide
21076
13
What is thermal decomposition?
© www.teachitscience.co.uk 2013
14
A: CO2
B: Throwing rubbish away.
Breaking a chemical
compound
down by
Answer
heating.
C: Breaking a chemical
compound down by cooling.
B: CaO
CaO
Answer
C: Ca2O3
Click for multiple choice
D: Breaking a chemical
compound down by heating.
Click for multiple choice
D: CO2
21076
15
What is the chemical name for
limewater?
© www.teachitscience.co.uk 2013
21076
16
What is the chemical formula for
limestone?
A: cloudy oxide
A: CLi2
B: calcium oxide
B: CaCO3
Answer
calcium
hydroxide
Answer3
CaCO
C: C4Ca
C: calcium hydroxide
Click for multiple choice
Click for multiple choice
D: CaO
D: calcium carbonate
© www.teachitscience.co.uk 2013
21076
What is the chemical symbol for
calcium oxide?
A: Melting a solid by heating.
© www.teachitscience.co.uk 2013
calcium
carbonate
Answer
21076
17
© www.teachitscience.co.uk 2013
21076
18
3