| A | B |
|---|
| Absolute Dating | determines the actual age of an object (e.g., 40 000 years) |
| Relative Dating | states how old one object is compared to another (e.g., older, younger) |
| Parent Isotope | the original radioactive element |
| Daughter Isotope | the product of radioactive decay (what the original element becomes) |
| U-238 | can be used to date old rocks and minerals |
| C-14 | used to date once living things |
| Half-life | the time required for half of a quantity of radioactive material to decay into a different element |
| 3 half-lives have passed | The amount of original parent isotope present will be 1/8 of its original quantity |
| 4 half-lives have passed | 6.25% of the parent isotope will remain |
| 2 half-lives have passed | The parent:daughter isotope ratio will be 1:3 |
