Atoms and Elements

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Across
  1. 2. Negatively charged electrons repel
  2. 4. Emission of energy
  3. 7. Particle with 2 protons and 2 neutrons
  4. 10. Subatomic particle, negative charge
  5. 11. e- on outermost energy shell
  6. 13. Subatomic particle, positive charge
  7. 15. The number of neutrons and protons
  8. 16. [Ar]4s2 3d2
  9. 17. A pure substance
  10. 19. The number of protons in an element
  11. 20. Atomic number 12
Down
  1. 1. Row on Periodic Table
  2. 3. Subatomic particle, neutral charge
  3. 5. Same element, different AMU
  4. 6. Center of an atom
  5. 8. electron occupies lowest energy possibl
  6. 9. Electron number variation
  7. 12. Building block of matter
  8. 14. each electron has a unique spin
  9. 18. Column on periodic table