Beacon Lesson Plan Library

What's the Matter? Locating Electrons in an Atom

Timothy Byrne


The students roll dice in order to simulate the probability of locating an electron in a certain region around the nucleus.


The student understands that protons and neutrons are located in the nucleus of the atom while electrons exist in areas of probability outside of the nucleus.


-2 dice (per group)
-4 10 cm strips of tape (per group)
-1 sheet of graph paper (per group)
-1 periodic table (per group)


1. Obtain die, masking tape, and graph paper from the store any time before the activity.
2. Review the student procedures.


*NOTE - This lesson will address a portion of the benchmark.

1. Model how to design a probability data table that can be used to record the data in an organized method to be analyzed later. This data table must include the three energy levels and the number of squares penciled in at each level.

2. Set students in groups of 2 - 4.

3. Distribute materials to groups.

4. Explain to students that each roll of the die will represent an electron's location in the area outside the nucleus. Show students the periodic table and review quickly electrons, protons, and neutrons.

Students will:

5. Prepare their data table.

6. Prepare their die in the following way:
Tape all six sides. Mark three of the sides with one dot each, two of the sides with two dots each, and the remaining side with three dots.

7. Select four squares adjacent to each and in the center of the graph paper. These four squares must make a larger square which will be used to represent the nucleus of the atom. Color in the square (nucleus) in with any color marker.

8. Roll the die and with each roll pencil in a square according to the following rules.

a. If a one is rolled, pencil in any square that is between 0 and 5 cm from the nucleus.
b. If a two is rolled, pencil in any square that is between 5 and 10 cm from the nucleus.
c. If a three is rolled, pencil in any square that is between 10 and 15 cm from the nucleus.
* Remember that each square on the graph paper represents one cm.

9. Repeat this procedure of rolling the die and marking the graph for 50 throws. Record your results in a data table.

10. The teacher will need to circulate around the class to assist the students where needed and to check for understanding that electrons exist in areas of probability outside of the neucleus. Give oral formative feedback.


Teacher observations of student activity are needed to determine student knowledge of electron probability positioning. The students will also identify where these electrons are located with respect to the nucleus.

Web Links

This site discusses the structure of the atom on a level easily enough for middle/high school students to understand.

Return to the Beacon Lesson Plan Library.