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= **QUESTIONS**  =

7. 7|How did Dalton define the term ‘element’?
8. 8|How much time passed between Democritus’ model of the atom and Dalton’s model? 9. 9|How did Dalton’s model of the atom differ from Democritus’ model? 10. What is an electron? Where is it found? 11. Who discovered the electron? In what year? 12. What experiment was used to discover the electron? 13. What is a cathode ray tube? 14. What was J.J. Thomson’s model of the atom? 15. What is radioactivity? 16. Who discovered radioactivity? In what year? 17. What experiment was used to discover radioactivity? 18. What contribution did Frederick Soddy make to the understanding of radioactivity? 19. What radioactive elements did Marie Curie and her husband Pierre first isolate? 20. What was the cause of Marie Curie’s death? 21. What did the discovery of radioactivity add to the understanding of the atom? 22. What is the nucleus of an atom? Where is it found? 23. Who discovered the nucleus? In what year? 24. What experiment was used to discover the nucleus? 25. What is a proton? Where is it found? 26. Who discovered the proton? In what year? 27. What experiment was used to discover the proton? 28. What was Rutherford’s model of the atom? 29. How did Rutherford’s model of the atom differ from Thomson’s model? 30. What was Bohr’s model of the atom? 31. How did Bohr’s model of the atom differ from Rutherford’s model? 32. What is a photon? 33. What happens to an electron when it absorbs a photon? 34. What happens when an electron drop to an orbit closer to the nucleus (a lower energy level)? 35. What is a neutron? Where is it found? 36. Who discovered the neutron? In what year? 37. What experiment was used to discover the neutron? 38. What is the ‘modern’ model of the atom (sometimes referred to as the electron cloud model)? 39. How does the modern model of the atom differ from Bohr’s model? 40. What is the difference between an ‘atomic orbit’ and an ‘atomic orbital’? 41. What contribution did Louis de Broglie make to the modern model of the atom? 42. What contribution did Erwin Schrödinger make to the modern model of the atom? 43. What contribution did Werner Heisenberg make to the modern model of the atom? 44. Where does most of the mass of an atom come from? 45. What is alpha radioactive decay? 46. What is beta radioactive decay? 47. What is gamma radioactive decay? 48. Which form of radioactivity is the most dangerous? 49.How can radioactivity be used to determine the age of objects?