1.  Radioactive Decay Bedrock Day 5 – March 1, 2013

2. Do Now  You have 100 skittles and a little sister to share them with. Your little sister comes back every five minutes to get more. You are watching your weight post-New Years and give her half of your skittles every five minutes. How many do you have left after 10 minutes? 20 minutes? Time (min) # Started with # Given Away # You Have Fractio n you have left 0 5 10 15 20

3. CATALYST  You have 100 skittles and a little sister to share them with. Your little sister comes back every five minutes to get more. You are watching your weight post-New Years and give her half of your skittles every five minutes. How many do you have left after 5 minutes? 10 minutes? 15 minutes? Time (min) # Started with # Given Away # You Hav e Fraction of the ORIGINAL you have left 010050 50/100 = ½ 55025 25/100 = ¼ 102512.5 12.5/100 = 1/8 1512.56.25 6.25/100 = 1/16

4.  AIM:  How do scientists figure out the absolute age of a layer of bedrock or a fossil?  Learning Target:  I can use radioactive dating to determine the absolute age of bedrock.  Agenda  Catalyst  Mini Lesson  Activity #1 - Paper Masterpiece!  Activity #2 – M&M Lab in the back Aim, Learning Target & Agenda

5. Radioactivity  The way scientists determine the ABSOLUTE AGE is by measuring how much of a sample is RADIOACTIVE.  When an atom is RADIOACTIVE, it is unstable and will change into a different atom over a certain period of time.

6. Radioactivity  The original atom is called the PARENT  The one it changes into is the DAUGHTER atom.  The change from Parent  Daughter is called RADIOACTIVE DECAY. 100 % Parent50 % parent25% Parent 75 % Daughter 50% Daughter

7. Radioactivity  The amount of time it takes ONE HALF of the material to decay is called a HALF LIFE. The amount of time in a half life is known and depends on the element. 100 % Parent50 % parent25% Parent 75 % Daughter 50% Daughter

8. Famous Radioactive Atoms

9. Paper Activity  We are going to be cutting paper. It is SO IMPORTANT that ALL YOUR PAPER ENDS UP IN THE TRASH.  Cut the paper as I tell you  Make a visual representation in each box  Write the fraction of the original remaining  Paper Model Master Paper Model Master

10. What did we notice?  Write the take-away statement at the bottom of the activity sheet.

11. Practice Questions

12. Do Now:  Base your answer on the accompanying graph, which shows the generalized rate of decay of radioactive isotopes over 5 half- lives. If the original mass of a radioactive isotope was 24 grams, how many grams would remain after 3 half-lives? [1]  12  3  24  6

13. Activity  In your Lab Books Find this page:

14. Activity  Working in pairs, you will complete the activity.  In the instructions where it tells us to “cut out the cards” we are going to just label the cards A – I, in the events that occurred 1 st being A and the event that occurred last being I

15. Do Now  Suppose you have a shark’s tooth that you suspect is about 15,000 years old. Would you use U-238 or C-14 to date the tooth? Explain your answer.  An organism was found to contain 6.25% of C-14 left in its remains. If the half-life of C- 14 is 5,730 years, about how long ago did the organism die?