1. SPS3c. Explain the process half-life as related to radioactive decay.
EQ: How is the half-life of a radioactive atom used to determine the age of ancient object?

2. HOW DID SCIENTISTS FIGURE MY AGE?
How old am I?
Natural mummy of a man from about 3300 BC (53 centuries ago).
HOW DID SCIENTISTS FIGURE MY AGE?

3. Story about how scientists determine age of “ICE” man and other ancient artifacts.
You probably have seen or read news stories about fascinating ancient artifacts. At an ar­chaeological dig, a piece of wooden tool is unearthed and the archaeologist finds it to be 5,000 years old. A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago. How do scientists know how old an object or human remains are? What methods do they use and how do these methods work? In today's lesson, we will examine the methods by which scientists use radioactivity to determine the age of objects, most notably carbon-14 dating.

4. Biological artifacts can be dated up to about 50,000 years old.
What is Carbon-14 dating?
Carbon-14 dating is a way of determining the age of certain archeological artifacts.
Biological artifacts can be dated up to about 50,000 years old.
It is used in dating things such as bone, cloth, wood and plant fibers.
How it works!

5. Time Mass 72 g Initial 10 minutes 20 minutes 30 minutes 40 minutes
Half-life Practice
The SI unit of activity is the becquerel (Bq).
Time
Mass
Initial
72 g
10 minutes
20 minutes
30 minutes
40 minutes

6. Problem #3 Half-life of 2 hours
Time
Mass Left in Nucleus
Initial
2 hours
4 hours
6 hours
8 hours
10 hours

7. Problem #4
Time
Mass Left in Nucleus
Initial
400 ?
3 days
100

8. Use your notes from 11/1 to complete the circle map:
Half-life

9. Problem 6 Most Stable to Least Stable Hint: the longer it takes something to decay the more STABLE it is.

10. Problem #8
Earth is 4,500,000,000
½ Life of Uranium-238 is 4,500,000,000
Hint = look at the numbers.
How much of the original Uranium-238 is left?

11. MAKE THE CHART TIME (half-life given) add half-life (time given)
Amount or Activity of Nucleus Left
divide by 2

12. Problem #9 = a WHOLE pie or 100% = INITIAL AMOUNT
= a HALF pie or 50% = ONE HALF LIFE HAS PASSED
= a QUARTER pie or 25% =
SECOND HALF HAS PASSED

13. More Practice Complete Number 4 to 7 on typed side.
Complete All on hand-written side.
Initial Amount
TIME
Half the Amount
Each Isotope takes a certain length of time to divide by HALF (half-life). DIVIDE BY 2!

14. TOD
If g of Carbon-14 decays until only 25.0 g of Carbon is left 11,460 years, what is the half-life of Carbon-14?