Matter & Atomic Structure

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Across
  1. 2. **** number; the total number of protons and neutrons
  2. 3. smallest unit of matter
  3. 6. a substance consisting of 2+ different elements
  4. 7. the tendency of an atom to attract electrons
  5. 8. anything that has mass and occupies space
  6. 9. ******* shell; the outermost electron shell
  7. 10. ****** number; the number of protons unique to that element
  8. 11. capacity to cause change
Down
  1. 1. different atomic forms of the same element
  2. 4. an atom (or group of atoms) that has gained or lost electron/s
  3. 5. a chemical that is not reactive; the valence shell is full
  4. 7. substance that cannot be broken down
  5. 8. a substance consisting of 2+bonded atoms