Kinetic Theory of Matter

Today I had to lecture on the Kinetic Theory of Matter in my Physical Science class.  It’s all about how the particles of matter are constantly moving, even in a solid.  I came up with three demonstrations that you might want to borrow.

First was discussing the nature of atoms being packed together in a solid.  I have a plastic jar of marbles.  Students can see how the marbles all nest together in the jar.  I gently rattled the jar to have them understand that the molecules (marbles) are in constant motion, even in a solid.  I then poured the marbles out into a box lid.  I showed how they poured just like a liquid, still took up the same volume, but flowed like a liquid and took the shape of the container like a liquid.

The second demonstration was simple.  I lit a match in the corner of the room and we waited while the smell found it’s way across the room to the students at the far end.  I used that to talk about how the molecules are moving very rapidly but bumping into one another, so it takes time for the smell to dissipate.

The third demonstration was the best of the day.  I put a beaker of water on the overhead projector and let it sit to remove turbulence.  I then carefully and gently added a drop of food coloring.  Because it was lit from underneath, the kids could see the snake-like tendrils working up and down and on the overhead they could see the color spreading out.  After watching for only a couple of minutes the color was mostly uniform.  They made me add additional colors and watched them swirl.