1. 7.2-Half-Life 7.3- Nuclear Rx Hulk smash! GRR! I ’ m going to teach you about half-life and nuclear Rx!

2. What is a half-life? The rate of radioactive decay can be compared using a quantity called half-life The rate of radioactive decay can be compared using a quantity called half-life Ex. The half-life of strontium-90 is 29 years. If you have 10.0g strontium-90 today, 29 years from now, you will have 5.0g left. Ex. The half-life of strontium-90 is 29 years. If you have 10.0g strontium-90 today, 29 years from now, you will have 5.0g left.

3. Isotopes An isotope of an element have nuclei with the same number of protons (the same "atomic number") but different numbers of neutrons. Therefore isotopes have different "mass numbers", which is the total number of nucleons (protons plus neutrons). An isotope of an element have nuclei with the same number of protons (the same "atomic number") but different numbers of neutrons. Therefore isotopes have different "mass numbers", which is the total number of nucleons (protons plus neutrons). Mass number= atomic number+ neutrons

4. Isotopes(pg2) Parent isotope: the isotope that undergoes radioactive decay Parent isotope: the isotope that undergoes radioactive decay Daughter isotope: The stable product of radioactive decay Daughter isotope: The stable product of radioactive decay

5. Subatomic Particles

6. Quiz Time!!! 1. What is an isotope? 2. What are the two types of isotopes? 3. What is a half-life? 4. Name 3 subatomic particles and their symbols.

7. Carbon Dating We can measure how the radioactivity in plant or animal remains has changed over time and calculate the age. We can measure how the radioactivity in plant or animal remains has changed over time and calculate the age. All organisms on Earth contain carbon. All organisms on Earth contain carbon. Radiocarbon dating is the process of determining the age of an object by measuring the amount of carbon-14 in that object. Radiocarbon dating is the process of determining the age of an object by measuring the amount of carbon-14 in that object.

8. Carbon Dating(pg.2) Carbon ’ s isotopes include carbon-12 and carbon-14 Carbon ’ s isotopes include carbon-12 and carbon-14 When an organism is alive, the ratio of carbon-14 atoms to carbon-12 atoms remains nearly constant. When an organism is alive, the ratio of carbon-14 atoms to carbon-12 atoms remains nearly constant. When an organism dies, that ratio decreases with time. When an organism dies, that ratio decreases with time. Hence, radiocarbon dating was born. Hence, radiocarbon dating was born.

9. Decay Curve A decay curve is a curved line on a graph that shows the rate at which radioisotopes decay. A decay curve is a curved line on a graph that shows the rate at which radioisotopes decay. Ex. Ex.

10. Radioactive Decay  Radioactive decay is the process in which unstable nuclei lose energy by emitting radiation.  Isotopes that are capable of radioactive decay are called radioisotopes.

11. Radioactive Decay Alpha Radiation An alpha particle is a positively charge atomic particle that has the same combination of particles as the nucleus of a helium atom. An alpha particle is a positively charge atomic particle that has the same combination of particles as the nucleus of a helium atom. It has an electrical charge of 2+ It has an electrical charge of 2+ A single sheet of paper stops alpha particles A single sheet of paper stops alpha particles Symbol: Symbol:

13. Video Time!!! http://www.youtube.com/watch?v=je9_Rt whjWg http://www.youtube.com/watch?v=je9_Rt whjWg

14. Radioactive Decay Beta Radiation A beta particle is an electron. A beta particle is an electron. It has an electrical charge of -1. It has an electrical charge of -1. It requires a thin sheet of aluminum foil to block. It requires a thin sheet of aluminum foil to block. Symbol: Symbol:

15. Video Time!! http://www.youtube.com/watch?v=t- NDf2JY6Pk http://www.youtube.com/watch?v=t- NDf2JY6Pk

17. Radioactive Decay Gamma Radiation It consists of high-energy, short- wavelength radiation. It consists of high-energy, short- wavelength radiation. Blocked by thick blocks of dense materials i.e. lead and concrete. Blocked by thick blocks of dense materials i.e. lead and concrete. Gamma decay results from a redistribution of energy within the nucleus. Gamma decay results from a redistribution of energy within the nucleus. Symbol: Symbol:

18. Video Time!!! http://www.youtube.com/watch?v=PW_K NP3glls http://www.youtube.com/watch?v=PW_K NP3glls

19. Can you think of an example of a product of gamma radiation?

20. Fission vs Fusion Fission is the splitting of a large atom into two or more smaller ones. Fission is the splitting of a large atom into two or more smaller ones. Fusion is the fusing of two or more lighter atoms into a larger one. Fusion is the fusing of two or more lighter atoms into a larger one.

22. QUIZ TIME!!! Name the 3 different radiation types. Name the 3 different radiation types. Define fission. Define fission. Define fusion. Define fusion. True or false: Gamma radiation is a stream of gamma particles. True or false: Gamma radiation is a stream of gamma particles.