1. Chapter 4 Chad Stessman

2. Half-life Radioactivity is a random process Half life is time it take half of the atoms of a sample to decay

3. Half-lives Tritium- 3 H- half life of 12.3 years 238 U has a half life of 3.8 billion years Amount remaining after a certain number of half-lives is 1/2 n. Where n= number of half lives

4. Radioisotope dating Radioactive decay can be used to determine the age of a sample.

5. Carbon-14 dating 14 C is an isotope of carbon. Formed by bombardment of nitrogen in the atmosphere with cosmic rays, neutrons

6. 14 C incorporates into living creatures through the carbon cycle.

7. 14 C incorporates into living creatures through the carbon cycle When plant or animal dies, it is no longer incorporating 14 C

8. 14 C half life is 5730 years After about 10 half-lives or 50,000 years too little 14 C to be effective. 14 C formation not always constant, need to find references

9. Tritium Dating 3 H has a half-life of 12.3 years Used to determine age of brandy and wine samples 10-100 years old

10. Other isotopes used in dating Potassium-40 1.3x10 9 years Rhenium-187 4.3x10 10 years Uranium-2384.5x10 9 years

11. Artificial Transmutation Middle ages alchemists tried to accomplish transmutation Nuclear reactions can change atoms

12. Uses of Radioisotopes Around 3000 radioactive isotopes can be produced from stable isotopes.

13. Tracers Used in physical, chemical or biological systems. Used to look for leaks, follow reactions, get images of biological processes.

14. Nuclear Medicine Radiation Therapy Diagnostic Uses

15. Radiation Therapy Use radiation to destroy rapidly growing cancer cells. Aim radiation at cancer cells

16. Diagnostic Uses of Radiation Radioisotopes are use to image or diagnose problems with the body functioning. Technium-99m-gives up a gamma ray to become more stable 99m Tc 99 Tc + gamma

17. Used in gamma imaging of heart.