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

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

2. 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

3. http://www.youtube.com/watch?v=KWAsz59F8gA

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. Nuclear Chemistry Student notes • Atomic nucleus: compared to the whole atom • (also called the nuclide) • Mass: • Energy • Volume

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

7. Nuclear Chemistry • Most atoms have tremendously stable nucleus • Exist for billions of years • A radioactive isotope has an unstable nucleus which undergoes spontaneous changes. • Note: spontaneous change ⇏ fast change • Transmutates into another element • The nucleus changes (different number of protons): • Emits particles and energy: Unstable isotopes are changing to become stable Student notes

8. Types of Radiation Understand the following slides on radiation emissions to complete the table in your notes.

9. Alpha Decay

10. Beta decay

11. Gamma Decay

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

13. Penetrating ability of different particles:Radition strength: how each of the radioactive emissions are blocked.Which is the most damaging (strongest)?

14. Nuclear reactions • Represents the nuclear changes • Use symbols to represent • The isotope before and after the change • The particles which are emitted • Before and after must balance

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

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

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

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

25. Radioactive decay Student notes: Notwo radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.

26. 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.

27. Half Life 4.5 years 12.5 g

28. Examples of the Half Life of Radioactive Elements

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

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

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

32. 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

33. 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

34. 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

35. 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?

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

37. Origins of Element Reading Analysis:

38. Teachers' Domain: The Origin of the Elements

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

40. 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)?