Rutherford 1
Name ______________________________________________ Date _________ Period ______
The Rutherford Experiment
Purpose
After reading the lab, create your own purpose below:
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Pre-Lab Discussion
Ernest Rutherford, famous for the “gold-foil experiment,” discovered that the core of an atom is
positively charged and named it the nucleus. He did this by shooting beams of positively charged
particles called alpha particles at a thin gold foil sheet. After measuring the different angles the
particles were deflected, he was able to better determine the shape and size of the nucleus. He
calculated that the radius of the nucleus was at least 10,000 times smaller than the radius of the
whole atom. This accounted for the over 99% of the particles that traveled through the gold foil and
missed the nucleus. Rutherford built his theory on the few alpha particles that were returned and
concluded that the nucleus was also positively charged because the alpha particles were being
reflected due to electrical repulsion. In light of this experiment, Rutherford rationalized that the
concentration of positive charges and the mass is in the core of the atom.
Materials
Rutherford Model Apparatus
Marbles
Wood Ramp
Graph paper
Ruler
Protractor
object
Procedure
1. Collect materials, including one wooden apparatus. Find the kit number on the side of the
apparatus and record it above the table in Data for Trial #1.
2. Tape a piece of graph paper in the middle of the board on the top side of the apparatus.
3. Labeling the starting point on the graph paper, roll a marble down the ruler into the
apparatus. As best as you can, trace the path of the marble on the graph paper.
4. On the table Data for Trial #1, mark an “X” in the column that best describes the way the
marble behaved when you rolled it. If it deflected at an angle, use a protractor to estimate the
angle the marble left at.
5. Continue until you have determined the object’s shape (at least 15 rolls). DO NOT PEEK
INSIDE THE APPARATUS!! Carefully remove the graph paper from the top of the kit.
6. Repeat steps 1-5 with a second apparatus. Tape the back side of the graph paper from the
first trial to the top of the new kit. Record the kit number and all data in Data for Trial #2.
Rutherford 2
Data for Trial #1
Marble
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Pass Through
Kit #___________
Deflected Back
Deflected at an Angle
Angle (degrees)
Rutherford 3
Data for Trial #2
Marble
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Pass Through
Kit #___________
Deflected Back
Deflected at an Angle
Angle (degrees)
Rutherford 4
Questions
1. Why do some of the marbles pass straight through, and others are deflected back? Explain
with respects to Rutherford’s experiment.
2. How can you determine what the shape of the object is and where it is located?
3. What difficulties did not being able to see inside the apparatus cause?
4. What is the shape of the object under the apparatus based on the different angles the marbles
are deflected out? Where in the structure is the object located? Answer for each trial.
5. Based on your findings, which takes up more volume of the apparatus: empty space or the
object. Explain.
Conclusion
How does this experiment relate to Ernest Rutherford’s discovery of the nucleus of an atom?