Purpose: To demonstrate how atoms combine to form molecules or compounds.
Hypothesis:
If an atom has ___________________________________________ then it will form a molecule or compound.
Materials:
5-10 Toothpicks
Marshmallows:
7 – White,
2- Green
1 - Pink
6 – yellow
5 – orange
Procedure:
1. Complete Data Table A below to predict how many valence electrons are required for each atom
to have a complete outer shell.
2. Use your Data Table A to assist with building your molecules.
3. Assemble your first molecule using toothpicks & correct color marshmallows.
4. Fill in the Data Table B after your model is complete.
5. Draw s model of your molecule in Data Table C.
6. Remove your toothpicks from your first model and use these toothpicks for your next model.
7. Repeat steps 3-6 for your next molecule.
Data Table A:
Atom
Oxygen (White)
Hydrogen (Yellow)
Carbon (Green)
Fluorine (Orange)
Nitrogen (Pink)
# of
Valence
Electrons
# of electrons needed
to complete shell
Data Table B:
Chemical
Formula
Oxygen
O2
Water
H2O
Carbon
Dioxide
CO2
Carbon
Tetrafluoride
CF4
Nitrogen
Trihydride
NH3
Number of atoms of Elements in the Molecules
Oxygen
Hydrogen
Carbon
Fluorine
Lithium
(White)
(yellow)
(green)
(Orange)
(Pink)
Total # of
Atoms
Data Table C:
O2
H2O
CO2
CF4
NH3
Analysis questions:
Answer these questions when you lab is complete.
1. How many valence electrons do these atoms have in its outer shell? How many more do they need
to become stable?
Sodium __________ , __________
Nitrogen __________ , __________
Neon __________ , __________
2. Why do atoms combine?
3. Build and draw two water molecules. Can you use these 2 water molecules to create 2 separate O2
and two H2 molecules?
4. Did you have to change any of the chemical bonds (toothpicks) in the above water molecules to
form the individual H and O molecules?
5. Do you think the H and O molecules have the same or different physical/chemical properties than
the water molecules?