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Itsy Bitsy
The search for the smallest particle of matter led scientists to develop new observation tools. Scientific observations using these new tools led to the discovery of small particles of matter including atoms. The image at the right is an electron microscope.
All matter is made up of these small particles or atoms.  Atoms are very small, too small for anyone to see.  In fact, if you enlarged a penny to the size of the United States, each atom in the penny would be only as large as a ping-pong ball.  Atoms are always moving, but the movement of one atom is very hard to observe, because it is so small.
Image courtesy of
United States Geological Society

If a marble, representing the nucleus of an atom, is sitting on second base in a baseball stadium, the entire stadium would represent the size of the atom.

Based on the above comparisons, which comparison below is a close approximation of the size of atomic particles? Drag your cursor over the correct picture.

A nucleus is to an atom as an ant is to an ....
(drag your mouse over your answer to check it!

A
           C
B
  D

A helium atom has two electrons, two protons, and two neutrons. Choose five other friends or members from your class or family, assign each the role of being either an electron, a proton or a neutron and have them demonstrate the position of these atomic particles in a helium atom. Out of small pieces of poster board write the letters "P" on two, "E" on two and "N" on two, representing protons, electrons and neutrons. Assign each person one card.

Scientists generally agree that a helium atom is arranged like this. (Drag your mouse over the link to see the answer of how you and your helpers should be arranged.)

Review science lab safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader , and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share a photograph of you or your friends doing this activity? Send the photograph attached to an e-mail with the following information: the title of the activity, the URL (Internet address), and your name. Remember that no pictures can be used which show any student faces or has a student name on it.

Updated August 11, 2005 by: Glen Westbroek

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