The Rutherford Experiment
Objective
Students understand the Rutherford experiment and how the nucleus of the atom was discovered. Students are introduced to
the atomic structure of an atom.
Explanation
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 that the radius of the whole atom. This, therefore, accounted for the 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. Due to this, 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
Figure 1
Procedure
1. Assemble into groups of two students.
2. Place a piece of graph paper in the middle of the board on the top side of the apparatus
3. One at a time, alternate rolling a marble down the ramp into the apparatus in order to discover the
shape of the object in the center of the board.
4. Observe and record the different directions and angles that the marbles are deflected out on the graph
paper.
5. Mark an “X” in the column the way the marble behaved when you rolled it.
6. Continue until you have determined the shape of the object.
7. Repeat recording the numbers of the kit you have used.
Page 1 of 4
Data Table
Kit #___________
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
Deflected Back
Deflected at an Angle
Angle (degrees)
Page 2 of 4
Kit #___________
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
Deflected Back
Deflected at an Angle
Angle (degrees)
Page 3 of 4
CP Chemistry
Activity: Rutherford Experiment
Name/Partners________________________
Date______________________ Pd. ______
Questions
1. What happens to the marbles when you roll them under the apparatus?
2. How does this experiment relate to Ernest Rutherford’s discovery of the nucleus of an atom?
3. Why do some of the marbles pass straight through, and others are deflected back? Explain with
respects to Rutherford’s experiment.
4. Why do some of the marbles shoot back out at different angles, while others come straight back at
you?
5. What is the shape of each object under the apparatus based on the different angles the marbles are
deflected out? Where is the object located?
First object:
Second object:
6. How can you determine what the shape of the object is and where it is located?
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