Periodic Table

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Across
  1. 4. particles that exist in the nucleus of atoms
  2. 7. the sum of the protons and neutrons in the atom
  3. 8. atoms with the same number of protons and different numbers of neutrons
  4. 9. the smallest particle that still can be considered an element.
  5. 10. the number of protons in the nucleus of an atom
Down
  1. 1. a positively-charged particle in an atom's nucleus
  2. 2. the average mass of all the isotopes of that element
  3. 3. a dense positive charge in the center of an atom
  4. 5. one-or two-letter abbreviation for the element
  5. 6. a chart showing all of the elements arranged according to the repeating pattern of their properties.