Anticipatory Set:
What do you guys think will happen if I take this balloon, rub it on my hair and then place it about 1 foot away from this pile of salt and pepper? What do you think will happen if I place it closer? Can anyone explain this phenomenon?
Teaching:
Draw an atom on the board.
Have the students name the subatomic particles and their charges.
Atoms are held together by the negative charge of the electron and the positive charge of the proton.
When an atom loses or gains an electron, it has an electric charge.
For example, if I have two atoms and 1 electron moves from atom 1 to atom 2, atom 1 now has a positive charge and atom 2 has a negative charge.
Guided Practice:
Let's do the experiment one more time and explain each step.
So every piece of matter in the world is made up of atoms and each atom is made up of protons, neutrons, and electrons.
The positive charge on the proton attracts the negative charge on the electron because opposites attract. If opposites attract then similar charges repel.
So why does the pepper jump? When I rub the balloon on my hair the electrons from my hair jump onto the balloon. Now that the balloon has more electrons than protons, it has a negative charge.
The pepper on the desk is neutral. The negatively charged balloon attracts the protons in the pepper and repels the electrons.
The closer I put the balloon to the pepper the stronger the attraction between the electrons and the protons. When the attraction is stronger the pepper jumps.
Why doesn't the salt jump? Well it would, but the salt is heavier than the pepper so it requires a larger electrical force. If I were to really really rub the balloon on my head hard, I may get enough electrons on the balloon to create a strong enough negative charge to attract the salt.
Independent Practice:
The students will work in table groups and use plastic wrap to see what items they can create an electric force strong enough to pick up. They will then need to explain why they were able to pick up certain objects and not others.
Closure:
The students will then need to explain why they were able to pick up certain objects and not others. At least one diagram will be required.
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