The Periodic Table

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Across
  1. 3. average mass of diff forms of the same element
  2. 5. what an element is identified as
  3. 6. regions around the nucleus
  4. 7. horizontal
  5. 9. vertical; families
Down
  1. 1. increases as you read left to right
  2. 2. located in the farthest level
  3. 4. the gas family; mostly non-reactive
  4. 8. a unique (set of) letter(s)