Prescriptive Activities: Facet Cluster 2.3: PF# 86
Breaking Marshmallow Bonds
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Prescriptive#86:
86 The student assumes that atoms can rearrange themselves without breaking bonds
(eg. Oxygen is accessible from compounds like CO2 without having to break CO2 bonds)
Materials:
Student handout
Marshmallows (3 different colors and sizes)
Toothpicks
Directions for Activity
For each reaction below:
1. Write the balanced equation
2. Select a marshmallow type to represent each element
3. Build the reactant molecules using toothpicks and sketch them under the
balanced equation.
4. Using only the reactant molecules, reassemble the atoms to create the products.
(More or less toothpicks may be used.)
5. Sketch the product molecules under the balanced equation
Reactions
1. Hydrogen gas (H2) and chloride (Cl2) react to form hydrochloric acid (HCl).
Balanced equation:
Reactant molecules
Product molecules
Prescriptive Activities: Facet Cluster 2.3: PF# 86
Breaking Marshmallow Bonds
Teacher Page
2. Magnesium (Mg) and carbon dioxide (CO2) react to form magnesium oxide (MgO)
and pure carbon (C). Recall that CO2 has two double bonds as shown here. These can
be represented by PAIRS of toothpicks: O=C=O.
Balanced equation:
Reactant molecules
Product molecules
Questions
1. Were you able to assemble the products using only the reactant atoms?
2. What must happen to reactant molecules before product molecules can be “built” in a
chemical reaction?
Prescriptive Activities: Facet Cluster 2.3: PF# 86
Breaking Marshmallow Bonds
Teacher Page
Teacher notes
Here is an example of a water molecule built of marshmallows and
toothpicks. For this activity we recommend different colored
marshmallows to more accurately represent the different atoms. For
best results, have at least 3 types (color or size) of marshmallows.
Small marshmallows can still be used to represent hydrogen.
Note about ionic crystal structure:
You may want to remind students that ionic compounds actually form large repeating
crystal lattices, and that the MgO that they build are the simplest representation of the
ratio and arrangement of atoms within the crystal.
Answer Key
H2 + Cl2  2HCl
2Mg + CO2  2MgO + C