Fellow name: Warren Essey

Title of Lesson: Atomic Structure - The Rutherford Experiment

School: University High School

Grade Level: 9-12

Subject(s): Physics or Chemistry

Summary

The lesson uses a large-scale activity to mimic the Rutherford experiment to discover atomic structure. Students will use ink in spray bottles to try to discover what hidden obstacles in a box look like. The results are similar to firing alpha particles at a nucleus. Afterwards they are shown the real results from the Rutherford experiment and use their knowledge from the large-scale experiment to infer what an atom's structure looks like.

In what way is your lesson/activity inquiry-based?

The students are given a lot of freedom in using the spray bottles to figure out what the obstacles are. Also they are expected to come up with ways to improve the experiment. This type of independent thought mimics real world experiments and encourages them to figure things out for themselves. The students are also given an incorrect picture of an atom and have to use their own results to infer the real structure of the atom, similar to what physicists in the early 1900s had to do.

Time Required

90 minutes

Group Size

3-4 per group

Cost to implement

$20 for spray bottles and ink

Learning Objectives

After this lesson, students should be able to:

Students should understand the internal structure of the atom and nucleus.

Students should know about and understand the results of Rutherford's experiment.

Students should be aware that real world experiments often don't get to see whether their results are correct but have to infer properties from experimental results.

Introduction / Motivation

Very little theoretical introduction needs to be given as they are meant to figure things out for themselves. I introduced the lesson as similar to a real world experiment that won a Nobel Prize. I explained that they need to figure out what hidden obstacles look like without ever looking inside, meaning they will never know the right answer. This will hopefully intrigue the students.

Also the fact that they get to use spray bottles full of ink will hopefully sound fun to them and different from many experiments.

Procedure

A cardboard box can be turned into a “detector” by cutting out windows at the back and sides of the box. A small hole also needs to be cut in the front big enough to spray ink through. The windows can be covered with sheets of paper that can be removed later. Obstacles made from cardboard can be glued or taped at various positions inside the box. The size and shape should vary from group to group. The box can then be placed upside down so that the obstacles can't be seen.

Students must never see inside the box. They begin by squirting ink in through the hole until they are satisfied they've covered as much of the inside of the box. Make sure paper or plastic is laid down on counters to prevent a mess.

Students can return to their desks while a teacher removes the paper “windows” from the “detector”, making sure students don't get to see inside.

The students try figure out what the obstacles inside the box looked like from their results. They can fill in their results and predictions on their handout. A series of questions will lead them from their results to the real results from the Rutherford experiment, asking students to infer the structure of an atom (see handout).

Using spray bottle (hidden behind box) to spray into hole cut into box. Hole is about the size of the spray bottle nozzle so students cannot see inside. Removable white sheets of paper have been placed over windows cut into box. Hidden obstacles are inside.

Materials List

Each group will need:

A spray bottle.

Ink and water.

Cardboard box with windows cut out.

Paper “windows”

Safety Issues

No safety issues, but obviously the ink can get messy so lab tables should be covered with paper and paper towels should be nearby.

Lesson Closure

It's best to go around during the lesson to see the ideas students are having and possibly prod them in the right direction. At the end of the lesson a picture of the atom and nucleus should be shown and a summary can be discussed with the class.

Is this lesson based upon or modified from existing materials? If yes, please specify source(s) and explain how related:

No.

References

None provided

Attachments

See Student Handout

List CA Science Standards addressed:

Chemistry 1e and 1h