7.3: Perform an Activity: Matching Models and
Formulas
pg. 252
The Chemical formula shows the number and types of
atoms in each molecule of a substance. For example; the
chemical formula for water is H2O. This tells us that each
molecule of water has two hydrogen atoms and one oxygen
atom. But chemical formulas do not tell us how the atoms
are arranged in a molecule. In this activity, you will make
models of common molecules to see how they are put
together.
Purpose: To build models of some common molecules.
Procedure:
1. Copy table 1 into your notebook.
2. The elements in the model kit are colour-coded. In
your notebook, record the name and colour of each
element you need.
3. Use the “atoms” and “bonds” provided to build a
model of each combination of elements listed in your
table. The molecule is complete when all the bond
holes are filled.
*Note: you can use only one atom of element 1 in
each molecule. However you can use as many atoms
of element 2 as are needed.
Materials:
Molecular Model Kit
Coloured Pencils
Table 1:
Element 1
(use only 1)
Element 2
(use more than
one, if
necessary)
Sketch of
Molecule
Chemical
Formula
Chemical Name
Use
H
H
Hydrogen
Fuel
Cl
Cl
Chlorine
Pool
disinfectant
H
Cl
Hydrogen
chloride
Used to make
Hydrochloric
acid
O
H
Water
Drinking
C
H
Methane
Fuel
N
I
Nitrogen
tri-oxide
Contact
explosive
O
O
Oxygen
Supports
burning
C
O
Carbon
dioxide
Puts out fires
Analyze and Evaluate:
a) Separate the molecules you built into two groups;
element and compounds. [t/i, c]
b) Why is the word, “diatomic” used to describe the
molecules of the elements? [t/i]
c) Compare the bonding in the Cl2 and O2 molecules. [t/i]
Apply and Extend:
d) The chemical formulas of hydrogen peroxide (H2O2)
and acetylene (C2H2) are similar. Build these
molecules. How are their structures different? [t/i]
a) Research the chemical properties and uses of
hydrogen peroxide and acetylene. Write a paragraph to
summarize your findings. [t/i, c]
b) Propane (C3H8) is a fuel commonly used for barbecues.
Use your kit to build a model of a propane molecule.
Draw and label you model.[t/i, a, c]