Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Plasma Explanation
Name: William
Status: student
Age: N/A
Location: N/A
Country: N/A
Date: N/A


Question:
What is a good way to explain plasma to 5th graders?



Replies:
I like to use "energy" to illustrate what is a plasma. I'm assuming your fifth graders know what an atom is, and that it has a nucleus and electrons. I would start by saying one big difference between states of matter is how energetic the atoms are. The energy I am talking about is the kinetic energy of the atoms -- how fast and how much they are bouncing back and forth into each other. A solid has less energy than a liquid (the atoms of a solid bounce around less than the liquid), which has less energy than a gas, which has less energy than a plasma. (You can use a box of balls, and shake the box to simulate the kinetic energy.) To explain a plasma, explain that the atoms of a plasma have so much energy that their electrons cannot even stay close to the nucleii. (Maybe put mittens on and shake your hands so that they fly off?). It is like a super-hyper gas that has so much energy that it behaves physically and chemically very differently than a gas.

Hope this helps,

Burr Zimmerman


William,

Plasma is a form of matter that is so hot (in terms of energy) that the electrons have been thrown from the atoms. Plasma is a bunch of atomic nuclei and unattached electrons. It is a fourth state of matter. The three most common are solid, liquid, and gas. Gas still has atoms and molecules, while plasma does not.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College


Dear William,

This explanation can be found in Paul Hewitt's Conceptual Physics in the chapter entitled The Atomic Nature of Matter. (Addison Wesley, 1999) I think it can be adapted for 5th graders easily. Someone may even own a plasma lamp that you could bserve with your students.

Matter exists in four phases. You are familiar with the solid, liquid and gaseous phases. In the plasma phase, matter consists of positive ions and free electrons. The plasma phase exists only at high temperatures. Although the plasma phase is less common to our everyday experience, it is the predominant phase of matter in the universe. The sun and other stars as well as much of the intergalactic matter are in the plasma phase. Closer to home, the glowing gas inside a fluorescent lamp is plasma.

In all phases of matter, the atoms are constantly in motion. In the solid phase, the atoms vibrate around fixed positions. If the rate of molecular vibration is increased enough, molecules will shake apart and wander throughout the material, jostling in non fixed positions. The shape of the material is no longer fixed but takes the shape of its container. This is the liquid phase. If more energy is put into the material so that the molecules move about at even greater rates, they may break away from one another and assume the gaseous phase.

All substances can be transformed from one phase to another. We often observe this changing of phase in the compound H2O. When solid, it is ice. If we heat the ice, the increased molecular motion jiggles the molecules out of their fixed positions, and e have water. If we heat the water, we can reach a stage where continued increase in molecular motion results in the separation between water molecules, and we have steam. Continued heating causes the molecules to separate into atoms. If we heat these to temperatures exceeding 2000 degrees C, the atoms themselves will be shaken apart, making a gas of ions and free electrons. Then we have a plasma.

I hope this makes sense to you and to your class. Thanks for thinking scientifically!

Martha Croll



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory