2. 1. What is radioactivity? Radioactivity is the process in which an unstable atomic nucleus emits charged particles and energy. 2. What is a radioisotope? Any atom containing an unstable nucleus is called a radioactive isotope, or radioisotope for short. 3. What happens during nuclear decay? During nuclear decay, atoms of one element can change into atoms of a different element altogether.

3. 4. What is an alpha particle? An alpha particle is a positively charged particle made up of two protons and two neutrons—the same as a helium nucleus. 5. What symbols are used to represent the alpha particle? The symbol for an alpha particle, 4 He, shows its mass and charge. It can also be symbolized as  6. How far do alpha particles travel and how can they be stopped? Most alpha particles travel no more than a few centimeters in air and can be stopped by a sheet of paper or by clothing.

4. 7. What is a beta particle? A beta particle is an electron emitted by an unstable nucleus. 8. What symbols are used to represent a beta particle? The symbol for a beta particle is 0 e or  9. How could a beta particle be stopped? Beta particles can pass through paper, but can be stopped by a thin sheet of metal. 10. What is a gamma ray? A gamma ray is a penetrating ray of energy emitted by an unstable nucleus.

5. 11. What symbol is used to represent the gamma ray? The symbol for a gamma ray is . 12. What does it take to stop a gamma ray? It can take several centimeters of lead or several meters of concrete to stop gamma radiation. 13. What is background radiation? Background radiation is nuclear radiation that occurs naturally in the environment. 14. What effect does dangerous ionizing radiation have? Ionizing radiation can break chemical bonds in proteins and DNA molecules.

6. 15. What devices can be used to detect nuclear radiation? Devices that are used to detect nuclear radiation include Geiger counters and film badges. 16. What is half-life? A half-life is the time required for one half of a sample of a radioisotope to decay. 17. How do nuclear decay rates differ from chemical reaction rates? Unlike chemical reaction rates, which vary with the conditions of a reaction, nuclear decay rates are constant

7. 18. How do scientists determine the age of an object that contains carbon-14? In radiocarbon dating, the age of an object is determined by comparing the object’s carbon-14 levels with carbon-14 levels in the atmosphere. 19. Over very short distances which is greater, the strong nuclear force or the electrical forces among protons? Over very short distances, the strong nuclear force is much greater than the electric forces among protons. 20. Which atoms are radioactive? All nuclei with more than 83 protons are radioactive.

8. 21. What occurs during nuclear fission? Fission is the splitting of an atomic nucleus into two smaller parts, and tremendous amounts of energy. 22. What is the mass energy equation? E = mc 2 Energy = the mass x the speed of light squared 23. According to the mass energy equation, a small amount of mass releases how much energy? The conversion of a small amount of mass releases an enormous amount of energy.

9. 24. What occurs during a chain reaction? In a chain reaction, neutrons released during the splitting of an initial nucleus trigger a series of nuclear fissions. 25. What is critical mass? A critical mass is the smallest possible mass of a fissionable material that can sustain a chain reaction. 26. What are some advantages and disadvantages of nuclear power plants? Nuclear power plants do not emit air pollutants. Workers need to wear protective clothing to reduce their exposure to nuclear radiation. Nuclear power produces radioactive isotopes with half-lives of hundreds or thousands of years.

10. 27. What is fusion? Fusion is a process in which the nuclei of two atoms combine to form a larger nucleus. 28. What are the two main problems in designing a fusion reactor? Two main problems in designing a fusion reactor are achieving the high temperatures required and containing the plasma. The next two questions will be on the board for you to copy. 29. Beta 30.Alpha

11. 31. After 60 hours, 13.0g of a sample of sodium- 24 remains unchanged. If the original sample had a mass of 208g, what is the half life of sodium-24? 208g/13g = 16 half lives 60hr/16 half lives =3.75 hours 32. Potassium-42 has a half-life of 12.4 hours. Suppose you have an 848g sample of potassium- 42. How much of the sample remains unchanged after 62.0 hours? 62hr/12.4hr = 5 half lives 848g/2=424/2=212/2=106/2=53/2=26.5g Or 1/2x1/2x1/2x1/2x1/2= 1/32 848 x 1/32 = 26.5

12. 33. What makes fusion more preferable over fission? Answer> Fusion releases more energy than fission, it uses readily available hydrogen fuel, and does not produce radioactive wastes. Fission produces many radioactive isotopes that last for thousands of years. Operators may lose control of the reactor resulting in a meltdown. What make fusion more complicated? Answer> Fusion requires high temperatures and the reactors must contain plasma.

13. 34. What are some sources of background radiation in your everyday environment? Radioactive isotopes in the air ground and water, radon gas from the ground, What is the source of background radiation that comes from space? Cosmic rays