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NAME: _______________________________ CHEMISTRY I CHAPTER 4 #4 (Questions 1-10) Write the letter of the answer that best completes the statement or answers the question. _____ 1. Which of the following determines the identity of an element? A. atomic number B. mass number C. atomic mass D. overall charge _____ 2. Which statement about protons is true? A. Protons have a mass of 1 amu. 1840 B. Protons have no charge. C. Protons are part of the nucleus of the atom. D. Protons circle the nucleus of an atom. _____ 3. Isotopes exist because atoms of the same element can have different numbers of A. protons B. neutrons C. electrons. D. none of the above _____ 4. Which of the following statements in Dalton’s atomic theory was shown to be incorrect by the results of Thomson’s cathode-ray tube experiment? A. All substances are made of atoms. B. Atoms are small particles that cannot be created, divided, or destroyed. C. Atoms of the same element are exactly alike, and atoms of different elements are different. D. Atoms join with other atoms to make new substances. _____ 5. Which particles make up a nucleus? A. electrons and neutrons B. protons and neutrons C. protons and neutrons D. electrons, protons, and neutrons _____ 6. If a boron atom has 5 protons, 6 neutrons, and 5 electrons, it has a mass number of A. 11 B. 10 C. 6 D. 5 _____ 7. The current model of the atom suggests that A. electron clouds surround the nucleus B. protons clouds surround the nucleus C. electrons travel in definite paths around the nucleus D. the exact path of a moving electron can be predicted _____ 8. Which of the following scientists discovered the nucleus? A. Dalton B. J.J. Thomson C. Rutherford D. Bohr _____ 9. How many oxygen atoms are there in Al2(SO4)3? A. 2 B. 3 C. 7 D. 12 E. 14 _____10. An atom of 214Pb undergoes beta particle decay. Which of the following isotopes does it become? A. 21080Hg B. 21483Bi C. 21481Tl D. 21482Pb 11. What is the most abundant element on the earth (including the crust, oceans, and atmosphere)? _________________________ 12. Where do the radioactive particles come from during nuclear reactions? _________ 13. When an unstable nucleus produces an alpha particle, by how many units does the atomic number of the nucleus change? ___________ Does the atomic number increase or decrease? _________ 14. How is it possible for the fission of 23592U, once started, to lead t o a chain reaction? 15. Compare and contrast nuclear fission and fusion. 16. What does it mean to say that fissionable material possesses a critical mass? Can a chain reaction occur when a sample has less than the critical mass? Explain your answer. 17. What are some reasons why no practical fusion reaction has been developed yet? 18. Silicon-31 has a half-life of 2.5 hours. If we begin with a sample containing 1000 mg of Si-31, what is the approximate amount remaining after 10 hours? (Questions 19-22) Supply the missing particle in the following: 19. _________ 20. 137 57La 21. 131 22. 201 80Hg + I ---- + ------- 0 -1e 210 Po + ---- 131 54Xe 4 2He _________ + 0 0γ + ________ ______ ------ 201 79Au (Questions 23-26) Write a balanced nuclear reaction for the following: 23. iodine-136 decays by beta particle production 24. 210 25. thorium-230 decays by alpha particle production 26. lead-214 emits a beta particle 27. Sodium-24 is used as a radiotracer. It has a half-life of 14.8 hours. What fraction of an administered dose of sodium-24 would remain in the body after 3.0 days? 28. If gold-189 has a half-life of 2.7 days, how long would it take for 1 mg of gold to become 1/8 as radioactive as it was at the beginning of an experiment? Po emits an alpha particle and 2 gamma rays MORE QUESTIONS ON THE BACK (Questions 29-34) Complete the following table: You need to fill in the blanks with the italicized numbers. SYMBOL PROTONS NEUTRONS MASS NUMBER 32 15P 29. ________ 30. ________ 32 31. __________ 107 33. __________ 61 47 27. __________ 27Co 52V 32. _________ 23 29 34. __________