Names: __________________________
__________________________
__________________________
Date: ___________ Period: ___
LAB – Rutherford’s Experiment (but with marbles!)
____ / 40
Purpose:
Chemistry experiments are often designed to gather information about what cannot be
directly observed. The purpose of this activity is to demonstrate how an experiment can
provide information about something that cannot be seen, specifically, the unknown size
of an object without direct measurement. Rutherford was able to estimate the size of the
atomic nucleus relative to the size of an atom without measuring it with a ruler.
Likewise, you will calculate the size of a marble without directly measuring.
Materials:
6 marbles
2 meter sticks
masking tape (~60 cm)
Procedure:
1. Use masking tape to make a line approximately 60 cm long across the end of your table-desk.
Place 2 chemistry books as a wall along the tape line and 1 meter stick along each side.
Measure the exact length of the line between the meter sticks in the data
and record in the Data as Width of field.
2. Place 5 marbles along your tape-line across the field width (evenly or unevenly
spaced is fine). Place a meter stick along each side as barriers. Place the remaining
marble about 1 meter away from the lined up marbles.
3. Without really looking or aiming, one partner will gently roll (not bounce) the single
marble toward the line of marbles. Another partner will record if there is a hit or a
miss for each trial. This partner will replace a hit marble back into position and return
the bombarding marble to the other partner for another trial. Continue for 25 trials.
4. Each partner perform 25 trials each until there is a total of 75 trials for the group.
5. Total the number of hits and misses for you and your partners. Record these totals in
your data table. (Relax, there is no competition here, the goal is not to get all hits!)
6. Collect the total numbers of hits and trials from all the lab groups, add them with
your own totals, find the class average, and record in the table under Class Data.
1
Data: (6 pts)
Group Data:
Class Data:
A. Width of field
_____ cm
B. Number of targets
_____
C. Total number of hits
_____
_____
D. Total number of trials
_____
_____
E. Actual diameter of marble
_1.3_ cm
Analysis and Calculations: (34 pts)
1. Calculate the class average number of hits per group (class hits divided by number of class groups).
Were there more or fewer hits in your own trials versus the class average? (4)
Class Average Hits: ____
Our group had more or fewer than class average (circle one)
2. Assuming you cannot change the number of marbles and you cannot aim, what does
the hit/miss ratio depend on? (changing what would cause more or fewer hits?) (2)
______________________________________________________
3. Calculate the diameter of the marbles from your own group data.(SHOW the WORK) (4)
Equation:
(width of field) x (hits)
Diameter = _______________________________
= ____ cm
(2) x (# of target marbles) x (trials)
Your Work:
Diameter =
_____ cm
4. Calculate the marble diameter from the total hits and trials for the whole class using
the same equation but with class totals data. (SHOW the WORK) (4)
Your Work:
Diameter =
_____ cm
2
5. Was the individual group or the class average results closest to the actual value for
the diameter of the marble that the teacher gave you? (2)
________________________________________________________
6. How would your answer have changed if the marbles were twice as large? (4)
________________________________________________________
What if they were half as large?
________________________________________________________
7. How does the number of trials affect the results? (2)
________________________________________________________
8. Consider the gold foil experiment carried out by Ernest Rutherford.
What is the marble in your experiment similar to in his experiment? (4)
________________________________________________________
When you calculate the diameter of the marble, it’s similar to calculating the diameter
of the ______________ in an atom. The width of field in your experiment is similar
to all of the _____________________ in an atom.
9. How did the model of the atom change based on the conclusion reached after
Rutherford analyzed the results of his experiment? (4)
________________________________________________________
________________________________________________________
10. Calculate what percent of the width of field one marble actually takes up. (4)
size of marble x 100 =
width of field
% of the space is the marble, the rest is ________ ________.
(show work)
3
Data Collection Workspace: Mark an X in the box for either a hit or a miss.
Partner 1
Trial:
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
Hit:
Miss:
Partner 2
Trial:
Hit:
Miss:
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
Partner 3
Trial:
Hit:
Miss:
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
Total Trials:
75
Total Hits:
___
Total Misses: ___
4