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Chapter 4, Lesson 1 Multimedia

Pencil Zoom

A three-tiered diagram of a pencil.  There is a close-up view of the graphite, showing carbon atoms, and then a close-up view of one of the carbon atoms, revealing the protons, neutrons, and electrsons of which it is composed.
  • The “lead” of a pencil is actually made of a substance called graphite which is made of carbon atoms.
  • The picture shows a close-up of one carbon atom.

Protons and Electrons

  • Protons have a positive charge. Two protons repel each other.
  • Electrons have a negative charge. Two electrons repel each other.
  • A proton and an electron have opposite charges and attract each other.

Hydrogen Atom

  • A hydrogen atom has one proton as the nucleus and one electron in the region outside the nucleus.
  • The electron and proton are attracted to each other. This attraction holds the atom together.
  • It is not possible to locate the exact position of an electron but the electron cloud shows the region where an electron is most likely to be.

Charged Plastic and Hand

A diagram of a neutral piece of plastic and a neutral area of skin on a person's hand.After the person runs the plasic between their fingers, some of the elctrons are transferred to the plastic, giving it a negative charge, and giving the skin a positive charge. A diagram of a neutral piece of plastic and a neutral area of skin on a person's hand.
  • When the plastic strip is rubbed on the skin, electrons from the skin are transferred to the plastic giving the plastic a negative charge.
  • When the plastic is moved near the desk, electrons in the desk are repelled by the negatively charged plastic.
  • This leaves an area of positive charge in the desk near the plastic.
  • The negative plastic and the positive area of the desk attract.

Balloon and Water

  • When the balloon is rubbed on hair or clothes, electrons move onto the balloon giving it a negative charge.
  • When the negatively charged balloon is brought near the water, electrons are repelled and move away from the balloon, leaving a positive area of the water near the balloon.
  • The negatively charged balloon and the positive area of the water attract.