TITLE: Atomic Structure: Rutherford’s Experiment
PURPOSE: In part I, the purpose of this lab is to determine the size and shape of an
object by indirect means. In part II, the purpose of this lab is to determine the
configuration of the partition inside the disc.
BACKGROUND INFORMATION:
Imagine how little you would be able to
accomplish if the room in which you
worked were so dark that you could not
see the materials you were working with.
Imagine how limited your observations
would be if the object of your scrutiny
were so small that it could not be seen,
even with a microscope. When you
think of how difficult experimentation
would be under such adverse conditions,
you will gain some appreciation for the
enormous technical problems
confronting early atomic scientists.
These scientists had as their
target—the atom—a bit of matter so
small that there was no hope of seeing it
directly. Nevertheless, under the
leadership of British physicist E. R.
Rutherford, these ingenious
experimenters were able to establish that
the atom had a nucleus.
It is not practical to reproduce the
classic experiments of Rutherford and
his group in a high school laboratory.
Some idea of the challenge that faced
these researchers can be gained,
however, by playing the game described
below. This game simulates the
experiments done by the Rutherford
team. In playing, you will determine, by
indirect means, the size and shape of an
object that you cannot see or touch.
Also include in your background:
 A description (and picture) of Rutherford’s experiment in determining the atom
has a nucleus.
 Include what Rutherford’s conclusion was after his famous experiment.
 Describe Rutherford’s model of an atom.
 Include how this lab is similar to Rutherford’s experiment.
PROCEDURE:
PART I:
1. When you arrive at the lab station, you will find a sheet of cardboard, plywood or metal
resting on top of a hidden object. Do not look under the board! Roll a marble under the
board with moderate force. Observe where it comes out. (If the marble does not come
out, call the teacher to retrieve it for you, so that the shape of the object under the board
will remain a mystery!) Did the marble hit the object? Can you conclude anything about
the size or shape of the object from the path of the marble?
2. Working from all four sides, continue to roll the marble under the board, making
observations of the rebound path. Your goal is to determine the size and shape of the
object by this method. You may want to put a large sheet of construction paper on top of
the board so that you can trace the entry and exit paths of the marble. Do not draw
directly on the board.
3. When you think you know that size and shape of the object, draw a full-size sketch of it
on a piece of paper (i.e in your lab book). Check your results with the teacher. Do not
look under the board until the teacher confirms your results.
4. Complete TWO mystery objects in all.
PART II:
1. Record the OB-SCERTAINER number.
2. Carefully shake and tilt your OB-SCERTAINER.
3. From the sound and path of the steel ball, determine the shape and location of the
partition or partitions.
4. Draw your best guess in your lab book.
5. Complete for 12 OB-SCERTAINTER disks.
DATA TABLE:
PART I:
Object #1:
for example:
Object #2:
Part II
Disk #1
for example:
Disk #2:
Disk #3:
Disk #4:
Etc.
Calculations: N/A
Conclusion: Make sure you include this section. Ask yourself, what new information did
I gain through doing this lab. If you can’t think of anything to write, look to your
purpose and see if you’ve fulfilled your purpose.
Questions:
1. Until Rutherford’s model of the atom, what was the model of the atom that was
most commonly accepted by scientists? Describe this model.
2. In Rutherford’s experiment, identify the following:
a. What was shot
3.
4.
5.
6.
7.
b. What was the target made of
In Rutherford’s experiment, what was the expected result of the particles being
shot at the foil?
In Rutherford’s experiment, where did most of the particles go?
In Rutherford’s experiment, what was the unexpected result?
What did Rutherford conclude about the atom that would explain the unexpected
result? Explain.
Why is Rutherford’s model (with electrons orbiting the nucleus like planets
around the sun) not necessarily correct? Explain.