1. [

2. Click Here for Half-Life Demo
Time it takes half of the atoms in a radioactive sample to decay into other atoms.
Click Here for Half-Life Demo [

3. [ [

4. Half-Life
Isotope
Activity (Curies)
U-235
Am-241
3.24
Cs-137
86.4
I-131
123,500
The length of a half-life is related to how active the elements are. (This is measured in curies)

6. Half-Life
Problem:
If 13153I has a half-life of 8.04 days, how long will it take until only 25% of it is left?

7. Half-Life
2 half-lives =
16.08 days

8. Half-Life
Problem:
If a fossil only has 12.5% of 146C remaining, how old is it?
5730 x 3 = years

9. Half-Life
Problem:
If you start with 25 grams of 13354Xe, which has a half-life of 5.25 days, how much will be left after days?

10. Click Here for Radioactive Dating Game
Half-Life
Click Here for Radioactive Dating Game