Chemistry

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Across
  1. 2. The number of electrons in the innermost electron shell in an atom.
  2. 3. Negative charge in an atom.
  3. 5. Positive charge in an atom.
  4. 7. The center of an atom that has protons and neutrons.
Down
  1. 1. The 3 states of matter are _______, liquids, and gases.
  2. 4. The number of electrons on the outer electron shells of an atom.
  3. 6. No charge particle in an atom.