1. Radiometric Dating

2. Radiometric Dating: method of dating geological specimens by determining the relative proportions of particular radioactive isotopes present in a sample.
What does this mean????

3. Isotopes: atoms of the same element that have different numbers of neutrons

4. Radioactive isotopes have nuclei that decay at a constant rate
When they decay, they turn into a different isotope of the same element or a different element

6. Each isotope has a fixed decay rate
Using the decay rate, scientists measure the concentration of the original radioactive isotope and of the newly formed isotope

7. Half-Life: the time it takes for half the mass of a given amount of a radioactive isotope to decay into its new isotope

8. Example: Radiocarbon Dating
All living organisms contain the isotopes carbon-12 and carbon-14
Scientists determine the ratio of carbon-14 to carbon-12 found in the fossil and compare it to the ratio found in a living organism
With living organism, the ratio remains constant as it continues to take in carbon

9. When a plant or animal dies, it no longer absorbs carbon
The amount of radioactive carbon-14 decays, with its half-life of 5,730 years, to nonradioactive nitrogen-14, while carbon-12 remains constant

10. Other Examples