What is a good way to explain plasma to 5th graders?
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,
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
Illinois Central College
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
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!
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Update: June 2012