CHM1 Review for Exam 8 The following are topics and sample questions for the first exam. Topics 1. Subatomic particles a. Alpha, α b. Beta, β− c. Positron, β+ d. gamma, γ e. neutron, n f. proton, p 4 He2+ 0 -1e 0 +1e 0 0γ 1 0n 1 1 1p or 1H 2 Penetraing ability α < β− = β+ < γ 2. Nuclear Reactions a. Balancing nuclear reactions b. Types of nuclear decay (transmutations) i. Natural 1. Alpha 2. Beta 3. Gamma 4. Positron 5. Electron capture ii. Induced (artificial) decay 3. Half-life - the amount of time required for half of a radioisotope to decay. a. Fraction remaining = (1/2)N b. N = t/T1/2 where N is the number of half-lives, t is the total amount of time and T1/2 is the half-life of the isotope 4. Nuclear Energy a. Nuclear Weapons i. Gun type (Little Boy) ii. Implosion type (Fat Man) b. Nuclear reactors and power plant design i. Fuel rods ii. Control rods iii. Moderators iv. Cooling water v. Turbine vi. Containment and Shielding c. Nuclear waste and disposal CHM1 Review for Exam 8 5. Multiple Choice (2 pts each) 1. Which subatomic particle has no charge? (1) alpha particle (2) beta particle 2. Which radioisotope is a beta emitter? (1) 90Sr (2) 220Fr 3. (3) 37K (4) 238U According to Table N, which radioactive isotope is best for determining the actual age of Earth? (1) 238U (2) 90Sr 4. (3) neutron (4) electron (3) 60Co (4) 14C Which statement explains why nuclear waste materials may pose a problem? (1) They frequently have short half-lives and remain radioactive for brief periods of time. (2) They frequently have short half-lives and remain radioactive for extended periods of time. (3) They frequently have long half-lives and remain radioactive for brief periods of time. (4) They frequently have long half-lives and remain radioactive for extended periods of time. 5. Which type of radioactive emission has a positive charge and weak penetrating power? (1) alpha particle (2) beta particle (3) gamma ray (4) neutron 6. Which of these types of nuclear radiation has the greatest penetrating power? (1) alpha (2) beta 7. (3) neutron (4) gamma In the reaction 23993Np  23994Pu + X, what does X represent (1) a neutron (2) a proton (3) an alpha particle (4) a beta particle CHM1 8. Review for Exam 8 Which isotope is most commonly used in the radioactive dating of the remains of organic materials? (1) 14C (2) 16N (3) 32P (4) 37K 9. Alpha particles and beta particles differ in (1) mass, only (2) charge, only (3) both mass and charge (4) neither mass nor charge 10. Given the nuclear reaction: 60 27 Co  0-1e + 6028Ni This reaction is an example of (1) fission (2) fusion (3) artificial transmutation (4) natural transmutation 11. Which product of nuclear decay has mass but no charge? (1) alpha particles (2) neutrons 12. (3) gamma rays (4) positrons The change that is undergone by an atom of an element made radioactive by bombardment with high energy protons is called (1) natural transmutation (2) artificial transmutation (3) natural decay (4) radioactive decay 13. As a sample of the radioactive isotope 131I decays, its half-life (1) decreases (2) increases (3) remains the same 14. Nuclear fusion differs from nuclear fission because nuclear fusion reactions (1) form heavier isotopes from lighter isotopes CHM1 Review for Exam 8 (2) form lighter isotopes from heavier isotopes (3) convert mass to energy (4) convert energy to mass 15. Which type of radiation has neither mass nor charge? (1) gamma (2) neutron (3) alpha (4) beta 16. Which list of particles is in order of increasing mass? (1) proton --> electron --> alpha particle (2) proton --> alpha particle --> electron (3) electron --> proton --> alpha particle (4) alpha particle --> electron --> proton 17. After 32 days, 5 milligrams of an 80 milligram sample of a radioactive isotope remains unchanged. What is the half-life of this element? (1) 8 days (2) 2 days (3) 16 days (4) 4 days 18. Which process converts an atom from one element to another, when the nucleus of an atom is bombarded with high-energy particles? (1) artificial transmutation (2) natural transmutation (3) addition polymerization (4) condenstation polymerization 19. A fission reaction is similar to a fusion reaction in that both reactions involve (1) collisions between nuclei of high atomic number (2) collisions between nuclei of low atomic number (3) the conversion of mass to energy (4) the conversion of energy to mass 20. The half-life of a radioactive substance is 2.5 minutes. What fraction of the original radioactive substance remains after 10 minutes? (1) 1/2 (3) 1/4 (2) 1/8 (4) 1/16 CHM1 Review for Exam 8 21. Given the equation: 14 7 N + 42He --> X + 178O When the equation is balanced correctly, which particle is represented by X? (1) 0-1e (2) 11H (3) 21H (4) 10n 22. When cobalt-60 undergoes nuclear decay, it emits (1) a positron (2) a neutron (3) a beta particle (4) an alpha particle 23. Which equation represents a fusion reaction? (1) 21H + 21H --> 42He (2) 146C --> 0-1e + 147N (3) 23892U + 42He --> 24194Pu + 10n (4) 10n + 2713Al --> 2411Na + 42He 24. A fusion reaction is similar to a fission reaction in that both reactions involve (1) collisions between nuclei of high atomic number (2) collisions between nuclei of low atomic number (3) the conversion of mass to energy (4) the conversion of energy to mass CHM1 Review for Exam 8 Short Answer Base your answers to the following questions on the information below. Radioactivity at home You may be surprised to learn that you do not need to visit a nuclear power plant or a hospital X-ray laboratory to find sources of radioactivity. They are all around us. In fact, it is likely that you’ll find a few at home. Your front porch may incorporate cinder blocks or granite blocks. Both contain uranium. Walk through the front door, look up, and you’ll see a smoke detector that owes its effectiveness to the constant source of alpha particle emissions from Americium-241. As long as the gases remain ionized within the shielded container, electricity flows, and all is calm. When smoke enters the chamber, it neutralizes the charges on these ions. In the absence of these ions, the circuit breaks and the alarm goes off. Indicator lights on your appliances may use Kryton-85; electric blankets, promethium-147; and fluorescent lights, thorium-229. Even the food we eat is radioactive. The more potassium-rich the food source, the more potassium-40 – a radioactive isotope that makes up about 0.01% of the natural supply of this mineral – is present. Thus, brazil nuts, peanuts, bananas, potatoes, and flour, all rich in potassium, are radiation sources. --Chem Matters April 2000 25. (2 pts) Write the equation for the alpha decay that occurs in a smoke detector containing Americium-241 (Am-241). 26. (2 pts) How is the radioactive decay of Krypton-85 different from the radioactive decay of Americium-241? 27. (2pts) State one benefit or useful application of radioactivity not mentioned in this article. 28. (2 pts) State one risk or danger associated with radioactivity. CHM1 Review for Exam 8 In the 1920s, paint used to inscribe the numbers on watch dials was composed of a luminescent (glow-in-the-dark) mixture. The powdered-paint base was a mixture of radium salts and zinc sulfide. As the paint was mixed, the powered base became airborne and drifted throughout the workroom causing the contents of the workroom, including the painters’ clothes and bodies, to glow in the dark. The paint is luminescent because radiation from the radium salts strikes a scintillator. A scintillator is a material that emits visible light in response to ionizing radiation. In watch-dial paint, zinc sulfide acts as the scintillator. Radium present in the radium salts decomposes spontaneously, emitting alpha particles. These particles can cause damage to the body when they enter human tissue. Alpha particles are especially harmful to the blood, liver, lungs, and spleen because they can alter genetic information in the cells. Radium can be deposited in the bones because it substitutes for calcium. 29. (2 pts) Write the notation for the alpha particles emitted by radium in the radium salts. 30. (2 pts) How can particles emitted from radioactive nuclei damage human tissue? 31. (2 pts) Why does radium substitute for calcium in bones? 32. (2 pts) Explain why zinc sulfide is used in luminescent paint. 33. (2 pts) What is the formula for zinc sulfide? Matching (2 pts each) 34. Enter the appropriate number in the blank. ___ Alpha particle 1. 42He ___ Beta particle 2. 21H ___ positron 3. 0-1e ___ neutron 4. 10n ___ deuterium 5. β+ CHM1 Review for Exam 8 Balancing (2 pts each) What is the missing particle? 35. YZX  23490Th + 42He 36. 146C  YZX + 0-1e 37. 21H + YZX  42He + 10n 38. 23592U  42He + YZX 39. 167N  0-1e + YZX True/Correct the False (2 pts each) 40. A nuclear weapon based on a fusion reaction is more powerful than a fission weapon. _____ 41. A gamma particle is a high energy photon. ___ 42. A beta particle and a positron have the same charge. ____ 43. If a 1.0 g sample of a radioisotope has a half-life of 10 years, there will be 0.5 g of the radioisotope after 20 years. ___ 44. An alpha particle is positively charged. ___ Name the following ions 45. CO3246. SO4247. NO348. NH4+ 49. Cl- CHM1 Review for Exam 8 Answers 1. 3 2. 1, See Reference Table N which will be provided on the test. 3. 1, it has the longest half-life 4. 4 5. 1 6. 4 7. 4 8. 1 9. 3 10. 4 11. 2 12. 2 13. 3 14. 1 (3 is true for both and the question how they differ) 15. 1 16. 3 17. 1 18. 1 19. 3 20. 4 21. 2 22. 3 23. 1 24. 3 25. 24195Am  42He + 23793Np 26. 85Kr is a beta emitter, not an alpha emitter like 241Am. 27. Medical imaging. 28. May cause cancer. 29. 42He 30. Ionizing radiation can break chemical bonds. Ionization can either be the adding or removing of an electron from an atom or molecule to form a charge species. If this cause a bond to be broken in a molecule such as DNA, it can cause mutations. 31. Ra is in group 2, and therfore has similar chemistry to Ca since it forms a 2+ ion. 32. It acts as a scintilator. When hit with a particle it cause an electron to be excited to a higher energy level. When the electron falls back to a lower level it give off light. 33. ZnS 34. 1, 3, 5, 4, 2 35. 23992U 36. 147N 37. 31H 38. 23190Th 39. 168O 40. T CHM1 41. T 42. F, …have opposite charges. 43. F, …after 10 years. 44. T 45. Carbonate 46. Sulfate 47. Nitrate 48. Ammonium ion 49. Chloride Review for Exam 8