s8pe-207ci-ca
12/19/05
4:48 PM
MAZER
Page 215
Content Standard
8.3.a Students know the structure of the atom and know it is composed of protons,
neutrons, and electrons.
Divide the mass of the washers in can B by the
mass of the washers in can A. Record the value
under “Mass of the washers divided by can A” in
the column for can B.
Repeat step 6 for film can atoms A, C, and D.
Record the values in the appropriate spaces.
Round the values you obtained in steps 6 and 7
to the nearest whole number. Record the rounded
figures in the next row of the table.
Observe and Analyze
Write
It Up
1. RECORD OBSERVATIONS Be sure your
data table and calculations are complete.
Double-check your arithmetic.
2. ANALYZE DATA Examine your data table.
Do you notice any patterns in how the masses
increase? Given that all the washers in the film
can atoms have identical masses, what might
the ratio of the mass of the washers to the
smallest mass tell you?
Investigation Standard
8.9.e Construct appropriate graphs from data and develop quantitative statements
about the relationships between variables.
Write
Conclude
It Up
1. IDENTIFY LIMITS What can’t this activity
tell you about the identity of your film can
atoms? (Hint: Protons and neutrons in real
atoms have about the same mass.)
2. INFER Hydrogen has only a single proton in
its nucleus. If your film can atoms represent
the first four elements in the periodic table,
what are the numbers of protons and
neutrons in each atom?
3. APPLY Single atoms are far too small to
place on a balance. How do you think scientists determine the masses of real atoms?
INVESTIGATE Further
CHALLENGE Use a periodic table to find
the masses of the next two atoms (boron and
carbon). How many washers would you need
to make film can atom models for each?
3. PREDICT Assume there is only one washer
in can A. Estimate the number of washers in
the other cans and record your estimates in
the last row of the table.
4. GRAPH DATA On a sheet of graph paper,
plot the masses (in grams) of the washers in
the film can atoms on the y-axis and the
number of washers in each can on the x-axis.
Connect the points on the graph.
5. INTERPRET DATA Compare the masses
of your film can atoms with the masses of the
first four atoms on the periodic table. Which
film can represents which atom?
Modeling Atomic Masses
Observe and Analyze
ms
Table 1. Masses of Film Can Ato
A
B
C
D
Mass of film can
atom (g)
Mass of empty
film can (g)
Mass of washers (g)
Mass of washers
divided by can A
Value rounded to
nearest whole number
Estimated number of
washers in each can
Chapter 7: Atomic Structure and the Periodic Table 215
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