Valence electrons
The electrons in an atom's outer ring are called valence electrons, and they decide how a material behaves. You put copper, silver, aluminum, silicon, or plastic in a lamp circuit and turn the switch on.
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What to try
- 1Start on Copper with Switch set to Off. Copper has one outer electron, and it wanders loose from atom to atom.
- 2Set Switch to On. The loose electrons drift toward the positive end, and the lamp lights.
- 3Pick Plastic and set Switch to On again. Plastic holds its outer electrons in bonds, so almost no current flows and the lamp stays dark.
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More visuals
- What electricity isCurrent is electrons drifting along a wire. Look inside the copper and see how slowly they move, even though the lamp lights at once.
- Inside an atomEverything is made of atoms. Count the protons in the center and the electrons around it, then take one electron away.
- Opposite charges attractTwo like charges push apart, and two opposite charges pull together. Bring the balls closer and the force gets stronger.