1. 25.2 – Nuclear Decay

2. Objectives Compare and contrast alpha, beta and gamma radiation. Define the half-life of a radioactive material. Describe the process of radioactive dating.

3. Nuclear Radiation Particles and energy are released from a decaying nucleus http://abyss.uoregon.edu/~js/cosmo/lectures/lec07.html

4. Alpha particle Two protons and two neutrons with an electric charge of +2 Represented as a Helium molecule

5. Alpha Particles Leave charged ions in their path when they travel through matter Least penetrating form of nuclear radiation Can cause serious biological damage

6. http://library.thinkquest.org/3471/radiation_types_body.html

7. Smoke detectors give off alpha particles that ionize the surrounding air If smoke particles enter the ionized air, they will absorb the ions and electrons The circuit is broken and the alarm goes off

8. Transmutation Process of one element changing to another through nuclear decay

9. Beta particle An electron released at high speed when a neutron decays into a proton It is more penetrating than alpha particle http://www.radfreenm.org/pages/radbasics.htm

10. http://www.physics.isu.edu/radinf/beta.htm

11. Gamma rays Penetrating electromagnetic waves that carry energy but have no mass or charge Video Clip http://library.thinkquest.org/3471/radiation_types_body.html

12. Start here 1 st 5-1-13

13. http://w1.rso.utah.edu/train/basics.html

14. Half-life Is the length of time it takes half of the atoms of a sample of radioactive isotope to decay Half-lives vary from fractions of a second to billions of years Video Clip

15. http://www.regentsearth.com/Illustrated%20ESRT/Page%201%20(Radioactive %20Decay)/Radioactive%20Decay%20QuizMC.html

16. Radioactive isotopes Found in all rocks and minerals in varying amounts Unstable & breakdown spontaneously Radioactive decay occurs at a constant rate specific to each isotope

17. Radioactive dating Carbon dating –Can be used to date once-living materials Uranium dating –Can be used to date rocks

18. Radioactive decay When rocks form the amount of radioactive isotopes is set and decay begins. Radioactive isotopes break down into stable isotopes and the precise measurements of the amount of stable vs. radioactive isotopes. The ratio tells us how many years have passed since formation. Carbon-14 – all living things take in C-14, once they die they stop taking in C-14. As fossils are dating, the ratio of C-14 to stable carbon-12 is measured to determine how long ago the organism died. http://geomaps.wr.usgs.gov/parks/gtime/radiom.html

19. http://www.dlt.ncssm.edu/tiger/chem2.htm

20. In-Class Assignment/Homework 25.2 Enrichment WKT Key Terms WKT Friday – Radioactivity Lab