John and Christos' crossword

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Across
  1. 3. what-happens
  2. 5. 1,17
  3. 7. 2.8.8.16
  4. 9. single-atom-name
Down
  1. 1. 40th-element-of-the-periodic-table
  2. 2. mix-of-building-blocks
  3. 4. k
  4. 6. Water
  5. 8. Fe+C_alloy
  6. 10. Atoms-in-an-element