Atomic Theory

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Across
  1. 4. Table, organized chart of all naturally occurring and man-made elements
  2. 5. negatively charged particle, outside the nucleus
  3. 6. discovered the neutron
  4. 8. criticized Democritus's theory
  5. 9. having no charge, equal number of positive and negative charges
  6. 10. proposed the idea that electrons were in a fixed orbit around the nucleus
  7. 11. abbreviation for an element
  8. 15. number, another name of the number of protons
  9. 16. first proposed the idea that matter was made of atoms
  10. 19. neutral particle in the nucleus
  11. 20. developed the Plum Pudding Model, and is credited with discovering the electron
Down
  1. 1. his Gold Foil Experiment led to the discovery of the nucleus
  2. 2. the three particles that make up an atom
  3. 3. positively charged particle in the nucleus
  4. 7. all matter is composed of __________
  5. 12. developed the 5 points of the Modern Atomic Theory
  6. 13. substance composed of only one type of atom
  7. 14. number, protons and neutrons added together
  8. 17. number of elements on the periodic table
  9. 18. Mass, the average masses of all isotopes of an element