1. Absolute Dating Radioactive Dating

2. Radioactivity Almost all of the elements contain radioactive isotopes Isotopes are atoms of the same element with different atomic weights This is due to different numbers of neutrons in the nucleus.

4. Radioactivity The rate at which radioactive elements break down is predictable and specific to different isotopes. The rate of decay is not affected by external factors such as temperature, heat or pressure

5. Radioactivity We measure time of decay in Half-Life A Half-Life is the time it takes for the mass of one half of the radioactive element to decay into its daughter product.

7. A graph of radioactive decay looks like this:

8. Absolute Dating By comparing the ratio of Parent product to daughter product you can calculate the number of half-lives that have passed Materials with long half-lives are used to date old materials Materials with short half-lives are used to date young materials

10. Absolute Dating The age of the Earth was determined by the breakdown of different isotopes of uranium.

12. Absolute Dating Carbon 14 (C 14 ) is often used to date materials that were once alive. While the organism is living the amount of C 14 remains constant because of the exchange of carbon

13. Absolute Dating When the organism dies the C 14 breaks down into N 14 Due to the relatively short half-life of 5700 years C 14 is not useful for dating very old objects