Atoms: Their parts and their history

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Across
  1. 5. the number of protons is equal to the number of _________ in an atom.
  2. 8. the last name of the person who helped develop the quantum model.
  3. 9. there are ____ neutrons in a hydrogen atom.
  4. 11. if we zoomed in on an atom so it was the size of a football field, the nucleus would be the size of a ___.
  5. 14. the last name of the person who proposed the plum pudding model
  6. 17. the number of neutrons is equal to the __________ minus the atomic number (no spaces between these two words).
  7. 18. this lists atomic number, mass, and symbol (no spaces between these two words).
  8. 19. the last name of the person who proposed the planetary model.
  9. 20. atoms are made up of 99.9% __________ (no spaces between these two words).
  10. 21. protons and neutrons are ______ the nucleus
  11. 22. a representation of an idea, an object or even a process/system that is used to describe and explain phenomena that cannot be experienced directly.
Down
  1. 1. the analysis of the cathode ray led to the discovery of _________.
  2. 2. have a negative charge
  3. 3. the last name of the person who proposed the solid sphere model
  4. 4. related ideas that have been tested and are used to explain atoms and how they work (no spaces between these two words.)
  5. 6. have no charge
  6. 7. building blocks of matter
  7. 10. the last name of the person who proposed the nuclear model.
  8. 12. the number of protons in the nucleus (no spaces between these two words).
  9. 13. have a positive charge
  10. 15. anything that has mass and volume
  11. 16. electrons are _______ the nucleus