Name:____________KEY__________________Date:_____________________Period:_____
Electron Cloud
Activity Key
Objective
1. Graph the distribution of electrons around a central nucleus.
Introduction
The position of an electron in an atom cannot be determined at any given moment. However, the
region, or cloud, in which the electron can probably be found is predictable. The shape of these
clouds is determined mathematically using the wave-mechanical model of the atom. This lab
simulates the probable distribution of electrons around a central atom in a spherical s-orbital.
Materials (per lab group)
Felt-Tip Marker
Construction Paper
Procedure
1. Draw a central circle on the construction paper. Draw four equally spaced concentric
rings around the central circle. Your drawing should look like a target, filling up the
paper.
2. Place your target on the floor.
3. Drop your felt-tip marker from a height of 1 meter onto the target so that it marks the
target. Try to aim for the center bull’s eye. Repeat procedure 100 times.
4. Tally the number of marks in each ring of the circle. Record your data in the table.
5. Plot your results on a piece of graph paper. The number of marks should be plotted
on the y-axis and the numbered area on the x-axis.
Data Table (Example and graph)
Number of Marks
29
25
21
16
9
Distribution of Marker Hits
35
30
Number of hits
Ring Number
1 (innermost)
2
3
4
5
25
20
15
10
5
0
1
2
3
Ring number
4
5
Questions
1. Which target ring had the highest probability of a hit? Answers may vary—Ring 1 usually
has the highest probability
2. How are orbital pictures similar to your target? Answers may vary. The “hit” target illustrates
the probability of where a single s-electron might be found in its orbital.
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© 2004 High School Technology Initiative (HSTI) Educational Materials: The ATOM: Structure