C1 Crossword

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Across
  1. 3. Discovered the nucleus.
  2. 4. Form positive ions.
  3. 6. Property that can only be determined by studying a chemical reaction.
  4. 8. Form negative ions.
  5. 9. Atoms of same element - different number of neutrons.
Down
  1. 1. Discovered the neutron.
  2. 2. Property that can be observed/measured without a chemical reaction.
  3. 5. Discovered the electron.
  4. 7. Formed by the gain or loss of electrons.