1. Absolute Dating Notes pg 20 in TOC
EQ How does the amount of initial material in a sample change as time increases?
NC standard - 8.E2.1

2. Warm-up In your own words define relative dating. Include an example.
Today we are going to focus on absolute dating. Using context clues, create a definition for absolute dating and also provide an example.

3. Recap: Relative Dating
Used in geology to determine the order of events in relation to other events.
This doesn’t say anything about the exact age of rock layers or fossil remains
Known as the law of superposition

4. Answer the questions while viewing
What is radioactive decay?
What does it mean when something is stable or unstable?
What are some ways we use radioactive things?

5. *Absolute Dating: a specific way to determine the age of an object or rock layer.

6. How Do We Find Absolute Age?
*Some atoms are unstable and breakdown over time in another more stable form. This process is called radioactivity.
*Stable = Does not decay
*Unstable= they decay

7. So what is Radioactive Decay?
*The rate of change or breakdown of elements is measured in Half-lives.
*A half-life is the amount of time it takes for something to divide in half.
Measuring radioactive decay is used to determine absolute age of rock or fossil

8. *A look at half lives:

9. Carbon 14 Dating – A specific type of radioactive dating
*Carbon 14 Dating – A specific type of radioactive dating. Carbon is present in all living things, and in rare cases carbon is radioactive.
*The half live for Carbon 14 is 5,730 years
When looking at fossils, we calculate the rate of decay in order to tell use the age of the fossil or rock layer

10. *Special Type of Fossil
An Index Fossil is a fossil that was found in several different areas but only existed during a specific time span.
These characteristics make it extremely helpful when trying to date the age of a specific rock layer.
When you find index fossils in rock layers, it tells you the age of the rock layer that fossil was found in.

11. Try this
If Carbon-14 has the half-life of 5730 years, after 11,400 years approximately how many half lives would Carbon of gone through?

12. Try This!!
If an element was found with 100 atoms of Carbon, which has a half life of 5730 years; how much Carbon will remain after 3 half lives?

14. Bean Decay Lab

15. Testing out absolute dating
Problem:
How many half-lives does it take Rock X to turn into Rock Y
Hypothesis:
Materials:
Beans, container with lid

16. Create a graph like this in your notebook
Trials
# beans white side up

17. Testing out absolute dating
In this lab you are going to start with 100 beans. The beans represent fossil X atoms. For this lab you will model how radioactive dating works.
Count your atoms and make sure you have 100
Place them in the box with all them on the white facing side.
Close the lid and shake the box
Open the box and count the atoms that have the red side up. After you finish remove them from the box and graph your white side up results.
Repeat steps 3 and 4 until you get down to 1 or 0.

18. Bean Decay lab Questions
Was your hypothesis correct? Explain.
In this lab our trials stands for ___________
At the end of each trial , approximately what percentage are the atoms “decaying”?
Does the amount of time you shake the box affect the outcome? Explain.
Do the number of atoms you start with affect the outcome? Explain. For example if we only used 50 beans, would my data be different. Think about this and explain your answer. Include data and other info to support answer.
Relative dating is to law of superposition as absolute dating is to ___________
How do you think absolute dating differs from relative dating?
How would absolute dating support the theory that the Earth is old? Explain and use vocabulary terms

19. Look at the class master graph…
Why doesn’t everyone have the same results?
What can this tell us about the accuracy of half lives?

20. Ticket out the door
How do scientists use radioactive decay or absolute age to date fossils and artifacts?
How accurate do you think absolute dating would be? Give me a time frame.