1. Earth Science Dating with Radioactivity 12.3

2. Radioactivity The spontaneous decay of certain unstable atomic nuclei.

3. Half-life The time required for one half of the atoms of a radioactive substance to decay.

4. Radiometric Dating The procedure of calculating the absolute ages of rocks and minerals that contain radioactive isotopes.

5. Radiocarbon Dating Method for determining age by comparing the amount of carbon-14 to the amount of carbon-12 in a sample

6. What is Radioactivity? When nuclei are unstable, they spontaneously break apart, or decay, in a process called radioactivity.

7. What is half-life? A half-life is the amount of time necessary for one half of the nuclei in a sample to decay to its stable isotope.

8. What is radiometric dating? An accurate radiometric date can be obtained only if the mineral remained in a closed system during the entire period since its formation.

9. How is carbon-14 used in radiometric dating? When an organism dies, the amount of carbon-14 gradually decreases as it decays. By comparing the ratio of carbon-14 to carbon-12 in a sample, radiocarbon dates can be determined.