Physical Science of Water
When dissimilar materials are pressed together they form chemical bonds. The adhesive on plastic tape forms strong enough bonds to hold two pieces together. When pieces of tape are pulled apart the bonds break.
Pieces become charged because as the bonds break one surface keeps more electrons than the other surface. The surface with excess electrons carries a negative charge, while the other surface carries a positive charge.
In the last experiment, when you peeled the tapes apart you separated dissimilar surfaces, producing one negatively charged tape and one positively charged tape. The two tapes attracted each other because unlike charges attract. Pieces of tape that were charged in the same way bore like charges, and repelled each other. Ionic type chemical bonds work in much the same way.
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