Adapted from: Keiffer, B. (1995). Atom
Illumination. Science Teacher, 62:1, pp. 29-31.
- University of Virginia
- Physics Department
Not So "Bohr"-ing
A Physical Science Activity
2003 Virginia SOLs
- construct Bohr models of atoms;
- interpret data from the periodic table;
- use atomic number and atomic mass to determine structure of atoms.
- How can we make a model of an atom? Atoms are much too small
to be seen, but experiments on the behavior of atoms have allowed
us to understand that an atom is made up of protons and neutrons
in the nucleus and electrons in various orbitals around the
nucleus. Because the atom is so small and the electrons move so
quickly, it is difficult to know exactly how an atom looks.
However, we can develop models to help us understand them better.
This activity is written using the old toys called "Light Brites"
that consist of plastic pegboards in front of a light bulb. Colored
plastic bulbs are inserted into the peg holes to make a lighted
picture of sorts. Those actual "Light Brites" may not be available in
all classrooms; some schools have made a commitment to teach science
with toys when possible and may have several of the toys available.
Other objects could be substituted for the light bright such as
"Chinese Checker" marbles and boards or even pieces of paper to
represent the atomic components. The main idea is to provide students
an opportunity to produce a two dimensional model of the Bohr atom in
the class where teacher feedback is readily available.
The model fails to illustrate the modern atomic model that places
electrons in specific orbitals in a three-dimensional space-filling
model. However, it illustrates that electrons occupy areas of varying
distance from the central nucleus.
To print out the Student Copy only,
- Light Brites (one per group of 4 students)
- Bulbs for Light Brites (100 bulbs per group preferably of only
3 colors if possible)
- Student activity sheets
- Periodic Tables
- Tell the students they will work in groups to make models of
four common elements. Explain that the model has several
shortcomings (outlined in the "Background" section for this lab).
- Divide students into groups of four. Throughout the exercise,
each student will be assigned a specific job. The students will
rotate through each of the four jobs for each atom to offer
everyone an opportunity to perform all responsibilities. The jobs
- Researcher-locates the assigned atom on the periodic
table and ascertains the atomic number, atomic mass.
- Calculator-Calculates the number of protons, neutrons,
and electrons in the atom.
- Designer-Decides on the position and arrangement of the
parts of the atom to be constructed.
- Builder-Places the bulbs in the designated positions on
the Light Brite.
- Assign the class four different atoms to construct (hydrogen,
oxygen, carbon, and sodium, for example).
- One student from each group retrieves the Light Brite and 100
bulbs, in a sealed sandwich bag, from the teacher. (Massing the
bulbs before the activity and after will help ensure all are
- Each group constructs the first atom assigned by the teacher
on the Light Brite. The bulbs for the protons and neutrons should
be grouped as a nucleus at the center of the Light Brite board.
The bulbs representing electrons should be distributed around the
nucleus according to the accepted valence arrangement. When a
group completes construction of an atom, it should request that
the teacher inspect the work. Once the teacher approves the model,
each student should sketch the arrangement on the "Data Sheet".
- For each of the subsequent atoms, the students within the
group will rotate so everyone fulfills each responsibility.
Figure 1: A two-dimensional model of a sulfur
atom using 1 inch paper circles to represent
protons (blue), neutrons (green), and electrons
Figure 2: Atomic model of a magnesium atom using
gumdrops to represent protons (green), neutrons
(red), and electrons (orange).
To print out the Data Sheet only,
Atom #1 _______________
Atom #2 _______________
Atom #3 _______________
Atom #4 _______________
- Students pick an element to research using web and library
- Students produce a power point presentation on their element.
- Students post their element presentation to a class web page
as part of a "Cyber Periodic Table."
Students with Special Needs
This activity is accessible to most students; though if a student is unable
to manipulate small objects comfortably, the students within the groups may
not be able to rotate through all jobs assigned.
Click here for further
information on laboratories with students with special needs.
- Students draw arrangements of other atoms independently.
- Students independently make a two dimensional model of an atom
to be assessed by the teacher for accuracy.