SNC1D/1P Atoms, Elements, and Compounds/Exploring Matter
Student Activity: Rutherford’s Black Box
Topics
Timing
atomic structure
scientific method
preparation: 1–1.5 h (first time only)
demonstration: 15–20 min
Specific Expectations
SNC1D
A1.5 conduct inquiries, controlling some variables, adapting or extending procedures as
required, and using standard equipment and materials safely, accurately, and effectively, to
collect observations and data
A1.6 gather data from laboratory and other sources, and organize and record the data using
appropriate formats, including tables, flow charts, graphs, and/or diagrams
A1.10 draw conclusions based on inquiry results and research findings, and justify their
conclusions
C3.1 explain how different atomic models evolved as a result of experimental evidence (e.g.,
how the Thomson model of the atom changed as a result of the Rutherford gold-foil
experiment)
C3.2 describe the characteristics of neutrons, protons, and electrons, including charge, location
and relative mass
SNC1P
A1.1 formulate scientific questions about observed relationships, ideas, problems, and/or issues,
make predictions, and/or formulate hypotheses to focus inquiries or research
A1.5 conduct inquiries, controlling some variables, adapting or extending procedures as
required, and using standard equipment and materials safely, accurately, and effectively, to
collect observations and data
A1.6 gather data from laboratory and other sources, and organize and record the data using
appropriate formats, including tables, flow charts, graphs, and/or diagrams
A1.10 draw conclusions based on inquiry results and research findings, and justify their
conclusions
C3.1 identify the characteristics of neutrons, protons, and electrons, including charge, location,
and relative mass
Introduction
We are most accustomed to making observations directly with our eyes. Students therefore often
find it conceptually challenging to comprehend the reasoning and logic used by scientists
studying atoms that they cannot directly see. This activity allows the students to practice making
logical inferences in an experiment with very similar principles to that of Rutherford’s famous
gold foil experiment.
Materials
4 film canisters or wooden cylinders for each
“black box”
poster board, or ply wood cut into 30 cm ×
30 cm squares
4 screws
block of wood, about 5 cm across, cut into a
unique shape (e.g., square, circle,
diamond, or rectangle)screwdriver
glue (white glue or wood glue)
2 or 3marbles
Safety Considerations
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
Take care when handling wood-working equipment.
Use professional judgement with rowdy classes if students may be inclined to throw
marbles.
Procedure
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Screw the caps of the film canisters to the poster board/plywood at the four corners, and
then fasten the film canister bottoms to the lids.
Glue the uniquely shaped block of wood to the underside of the board (Fig.1). Do not use
screws because the students will be asked to determine where the “nucleus” is. Screws
passing through the board will give it away.
Predict/Explain
Have students predict how the path of the marble will be affected by variously shaped
wood blocks.
Observe
The students will take turns to roll or flick a marble under the poster board, and observe
where it exits. The students will need to record data about entry and exit points of the
marbles, as well as angles of deflection, and make logical conclusions about the shape of
the “nucleus.”
Explain
Ask students to reconvene in groups and discuss why the marbles deflect in the patterns
observed. They should try to make predictions, based on their observations, about the
location and shape of the “nucleus.”
Fig.1 Setup for activity
Disposal
Keep the “black boxes” for future use to save preparation time.
What happens?
In this model the marbles represent alpha particles interacting with the nucleus (the wooden
block). The alpha particles’ movement will be affected by the nucleus, and deflected at different
angles depending on the angle of incidence and the shape of the nucleus.
How does it work?
Students should be able to interpret the change in direction of the marbles and so draw
conclusions about the size and shape of the hidden object (Fig.2). This is the technique that
Rutherford used to develop his theory of atomic structure.
Fig.2 The marbles will be reflected differently, depending on the size and shape of the object
Teaching Suggestions/Hints
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Hardware and lumber stores sometimes cut wood to size for a small fee.
This activity works best if the students are able to interact with it directly, so it should be a
student activity rather than a demonstration. If you intend to ask the students to predict the
shape of the wood block, first draw some examples on the board showing how they would
expect the marbles to be deflected. To deter peeking, place the “black boxes” at the work
stations before students arrive in the room.
If you feel that your students will find making the predictions about nucleus shape too
abstract, you could make this activity more concrete (and more messy) by placing a large
sheet of white paper under the “black box” and dipping the marbles in water-based paint
before rolling them. This will record the path of the marble, allowing the paper to be
removed after the students have rolled about a dozen marbles so that they can get a clearer
picture what was happening inside the box.
An alternative exercise can be done by taking a small object such as a marble or a nail and
completely covering it with modelling clay. Give the students toothpicks and the clay ball,
and ask them to determine the shape of the hidden object just by probing the ball with the
toothpick
Next Steps
Now that students have acquired some understanding of how the concept of the atomic nucleus
was discovered, the next logical step is to explain the organization of electrons in the atom
according to the Bohr–Rutherford model. Show students how to represent electrons using Bohr–
Rutherford diagrams.
Additional Resources
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This detailed description is provided of the “Rutherford Roller” lesson includes photos of
the materials being assembled and diagrams explaining possible results of this simulation:
http://www.exo.net/~emuller/activities/Rutherford%20Roller.pdf
This video illustrates how Rutherford and his co-workers studied the angles at which alpha
particles were scattered as they passed through a thin gold foil and helped them to develop
the concept of an atomic nucleus: http://www.youtube.com/watch?v=5pZj0u_XMbc