Jack Stubleski

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Across
  1. 3. average mass of the naturally occurring isotopes of an element
  2. 6. =the number of protons
  3. 9. tiny very light particles, have a negative electrical charge and move around the outside of the nucleus.
  4. 10. an electron in the outermost energy level of an atom
Down
  1. 1. much larger and heavier than electrons, have a positive charge and located in the nucleus of an atom.
  2. 2. large and heavy like protons, have no electric charge and located in the nucleus of an atom.
  3. 4. discovered the neutron.
  4. 5. an atom that carries an electrical charge.
  5. 7. two atoms with different numbers of neutrons.
  6. 8. any of the possible energies an electron may have in an atom.