175

1234567891011121314151617181920212223
Across
  1. 3. Number of protons
  2. 4. Likely to decay
  3. 6. Charged atom or group
  4. 8. Vertical column in table
  5. 9. Protons plus neutrons
  6. 11. Group 17 nonmetals
  7. 13. Radioactive series
  8. 15. Time for half to decay
  9. 17. Horizontal row in table
  10. 20. Neutral atomic particle
  11. 21. Positively charged ion
  12. 22. Energy level of electrons
  13. 23. Poor conductor element
Down
  1. 1. Atomic core
  2. 2. Positive charge particle
  3. 3. Group 1 metals
  4. 5. Rare earth series
  5. 7. Metals in center of table
  6. 10. Good conductor element
  7. 12. Unstable nucleus emitting radiation
  8. 14. Negative atomic particle
  9. 16. Electron path
  10. 18. Between metal and nonmetal
  11. 19. Energy from unstable atoms
  12. 22. Not likely to change