Finding the Nucleus of a Helium Atom (see "Important Notice!")

Interactive, scaffolded model

Important Notice!

Due to a recent change in Quicktime, this activity will only work for computers using Quicktime version 6. We are working on fixing this problem, but it will take some time. Thank you for your patience.

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Overview and Learning Objectives

Introductory text explains that the way atoms are usually drawn, with a nucleus 1/10 to 1/4 the size of the whole atom, is out of proportion. Then the students are given an image of a helium atom that is about 4 cm across. They will not be able to see the tiny nucleus until they use a slider to magnify the atom almost 10,000 times, smoothly zooming into the center of the electron cloud to find the nucleus.

Students will be able to:

• adjust the magnification of a helium atom in order to understand the relative size of an atom to its nucleus.

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Central Concepts

Key Concept:

While atoms are extremely small, the nucleus, containing most of the atom's mass, is much smaller than the atom itself.

Additional Related Concepts

Physics/Chemistry

• Electron
• Nucleus
• Orbital

Systems

• Scale

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Textbook References

• Biology: Exploring Life - Chapter 4: The Chemical Basis of Life
• Web of Life - Chapter 2: Chemical Basis of Life

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Additional Info

Additional Questions

These are part of the "Questions for Understanding" section of the activity:

1. The atom (as defined by the size of the orbitals) is about 10,000 times larger than the nucleus. Give an example of something that is 10,000 times larger than something else. This will be a good comparison for the nucleus of an atom to the size of an atom.
2. Ernest Rutherford, when exploring the inner structure of atoms in 1910, performed the following experiment: He shot tiny nucleus sized particles called alpha particles at a very thin sheet of gold foil. Every once in a while (about 1 in 20,000) an alpha particle bounced back. Almost all of the others went straight through the foil. Based on your understanding of the structure of an atom (nucleus and electrons), why did he get those results?

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Activity Credits

Created by CC Project: Molecular Logic using Flash

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Requirements

• Java 1.5+ - Java 1.5+ is available for Windows, Linux, and Mac OS X 10.4 and greater. If you are using Mac OS X 10.3, you can download MW Version 1.3 and explore within it instead.
• QuickTime for Java - Important Note: Due to a recent QuickTime update, you may not be able to see some models with embedded Flash components. We are currently trying to develop a workaround.

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Technical Notes

Currently only works on Windows.

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