Essential Question: How do unstable (radioactive) isotopes become stable?

2. Nuclear ChemistryObjective: To explain the process of radioactive decay using nuclear equations and half life Essential Question: How do unstable (radioactive) isotopes become stable?

3. Radioactivity introduction - • Radioactivity video – 4 minutes • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall • Review questions: • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall#review • Dig deeper: • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall#digdeeper

4. Review: Radioactive Isotopes A radioactive isotope has an unstable nucleus that undergoes spontaneous changes. • Emits particles • 1. • 2. • Emits energy in the form of __________ waves. • Transmutates into another element

5. Types of Radiation

6. Alpha Decay

7. Beta decay

8. Gamma Decay

9. Particles emitted from a radioactive isotope Next slide Type Symbol Charge Mass Rad.Strength

10. Radiation Strength: Explain in your notes how each of the radioactive emissions are blocked.Which is the most damaging (strongest)?

11. Strong Nuclear Force:Holds the nucleus together Limit to the # neutrons: A nucleus with too many neutrons will be unstable and change

12. Balancing Nuclear Reactions • Keep track of atomic number (Z) and mass number (A): protons & neutrons • Totals of A & Z must be the same before and after the reaction. • Shown by “Before” “ After”

19. Nuclear reactions Total number of atomic numbers and the total mass numbers must be equal on both sides of the equation. Examples:

20. Nuclear Equations • 23892U  23490Th + ? • 146C  0-1e + ? • 23994Pu + 42He  24296Cm + ? Nuclear Equations Practice Website

21. Nuclear Reactions Emission of Alpha or Beta particles • http://phet.colorado.edu/en/simulation/beta-decay • http://phet.colorado.edu/en/simulation/alpha-decay

22. Radioactive decay No two radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.

23. Half-life • Measure of Radioactive decay rate. • Measured as the time it takes for ½ of a sample of radioisotope’s nuclei to decay into its products.

24. Half Life 4.5 years 12.5 g

25. Examples of the Half Life of Radioactive Elements

26. Tearing Through a Half Life800 Billion Bismuth-210 Atoms Time (years)

27. Half Life: • http://phet.colorado.edu/en/simulation/radioactive-dating-game Number of radioactive isotopes Number of years

28. Fission and Fusion • http://phet.colorado.edu/en/simulation/nuclear-fission

29. Half life Calculations • How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years? • Determine how many “half life intervals”. • Calculate the amount of original sample remaining after each ½ life 100g • Simplify the calculations

30. Half Life Problems • How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years? 3.1 g

31. Half Life Problems • How much of a 60g sample of an unstable isotope remains after 2 days if the half life is 12 hours? 7.5 g

32. Half Life Problems • How much of a 20 g sample of an unstable isotope remains after 3 sec if the half life is 0.5 seconds?

33. Fission and Fusion • http://phet.colorado.edu/en/simulation/nuclear-fission

34. Origins of Element Reading Analysis:

35. Teachers' Domain: The Origin of the Elements

36. Teachers' Domain: The Elements: Forged in Stars

37. Got Calcium • Where are most elements created? • When was H and He created? • What elements are made by small stars? • What additional elements are made by large stars? • What elements are made by supernovae (large exploding stars)?