2. When the nucleus of an atom breaks down to form a different element

3. Nuclear reactions involve the nucleus (protons and neutrons) BUT chemical reactions involve the transfer and sharing of electrons

4. Nuclear decay is a form of Ionizing Radiation: High energy that ejects electrons and transforms molecules into reactive unstable fragments Includes parts of the electromagnetic spectrum: UV, X-ray, Gamma Ray

5. LOW ENERGY HIGH ENERGY V I B G Y O R

6. After element 83 (Bismuth) the elements are naturally unstable and may emit decay particles After element 83 (Bismuth) the elements are naturally unstable and may emit decay particles The bigger the atom gets and the further from a 1:1 ratio of protons and neutrons, the less stable the atom is

7. Decay Type Symbol Comp osition Nuclear Symbol Strength Penetratin g Power Alpha Beta Gamma

9. 1.Write the nuclear symbol for the element that is given. 2.Draw an arrow. 3.Identify the type of particle that has decayed and write it after the arrow. 4.Balance the mass number (top) and the atomic number (bottom). 5.Identify the new element.

10. The superscript indicates the mass number and the subscript indicates the atomic number. C 12 6 X A Z Mass Number Atomic Number Element Symbol

11. Loss of an alpha particle 4 2 He 239 Pu  94 235 U  92

12. Loss of a beta particle 0 e 42 K  19

13. Loss of a gamma particle Alpha and gamma decay of: 0 0 γ 239 Pu  94

15. Time required for half a sample to decay The stability of the isotope is what determines the rate of decay. Less Stable = Faster Decay

16. After each half-life, half of the sample decays. Start = 100% 40 blue particles are present 1 half-life = 50% 20 blue remain 2 half-lives = 25% 10 blue remain 3 half-lives = 12.5% 5 blue remain 4 half-lives = 6.25% 2.5 blue remain Amount never becomes zero!!

17. After 10 half-lives sample considered nonradioactive because it approaches the level of background radiation. Because the amount never reaches zero, radioactive waste disposal and storage causes problems. Would you want radioactive waste stored in your community? How can we get rid of nuclear radioactive waste?

18. Example 1: The half-life of mercury-195 is 31 hours. If you start with a sample of 5.00 g, how much of it will still be left after 93 hours?

19. Example 2: How many half lives have passed if there is only 1.875 g left of a 30 g sample? If the half life for this sample is 1 hour, how many total hours have gone by?

21. Nuclear reactions power the sun Nuclear power plants provide electricity Medical uses: x-rays, cancer treatment, radioactive tracers Industrial uses: Sterilize equipment, sterilize (irradiate) food, x- rays of metal equipment (scan for cracks in airplanes) Military

22. Two light atoms combine to form a heavier atom of higher energy This reaction powers the sun!

23. One heavy atom breaks down into two or more smaller atoms and produces energy This becomes a chain reaction (as one atom splits and hits more, and those split and hit more) Supercritical: creates a great release of energy - atomic bomb Ping Pong Video

24. Controlled Fission: used for nuclear power Controlled Diagram: Control Rods to limit nuclear fission! Fission heats the water that turns to steam and moves the turbines