1. Nuclear Chemistry Chemistry

2. Chemical Reactions vs Nuclear Reactions Chemical ReactionsNuclear Reactions occur whenbonds are broken/formed nuclei emit particles/rays atoms are unchanged, but rearrangedoften changed involveonly electronsp +, n o and/or e - associated w/small energy changeslarge energy changes reaction rateinfluenced by temperature,not normally affected by pressure, concentration, &temperature, pressure, catalystsor catalysts

3. Nuclear Reactions nuclear reactions: reaction that involves a change in an atom’s nucleus -radioactivity: spontaneously emitting radiation -radiation: rays and particles emitted by a radioactive material -radioactive decay: loss of energy by a nucleus as it emits radiation until it forms a stable non- radioactive atom, sometimes of a different element

4. Types of Radiation 1. alpha particles: radiation made up of 2 protons and 2 neutrons ( 4 2 He nucleus) -has a +2 charge -example (nuclear equation): 226 88 Ra  222 86 Rn + 4 2 He notice mass is conserved: mass number: 88  86 + 2 atomic number: 226  222 + 4 -slow moving, so it is easily stopped by a piece of paper -are given the symbol, 

5. 2. beta particles: fast moving electrons -has a -1 charge -example 14 6 C  14 7 N + 0 -1  notice mass is conserved: mass number: 14  14 + 0 atomic number: 6  7 + (-1) -represented by  -very fast moving and have better penetration than alpha particles.

6. 3. gamma rays: high energy electromagnetic radiation that possesses no mass or charge -usually accompany  and  particles -example 238 92 U  234 90 Th + 4 2 He + 2 0 0  notice mass is conserved: mass number: 238  234 + 4 + 0 atomic number: 92  90 + 2 + 0 -represented by  -the best penetration of all types of radiation

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8. Nuclear Stability strong nuclear force: force that acts only on subatomic particles that are extremely close together that overcomes the electrostatic repulsion between protons All nuclei with more than 83 protons are unstable and decay spontaneously The main factor determining the stability of a nucleus is the ratio of neutrons to protons. -beta decay: neutron to proton ratio of 1.33:1 -alpha decay: neutron to proton ratio of 1.5:1 -gamma decay: neutron to proton ratio of 1.6:1

9. Writing and Balancing Nuclear Equations Solve the following problems to determine A, B and X. State the type of radiation emitted. 1. 15 8 O  A B X + 0 -1  2. 97 40 Zr  97 41 Nb + A B X 3. A B X  4 2 He + 214 82 Pb

10. Radioactive Decay Rates We can measure the decay rate of radioactive isotopes. half life: time required for one-half of a radioisotope’s nuclei to decay into its products. - amount remaining = (initial amount) x (½) n where n = number of half lives that have passed -example: If Sr-90’s half life is 29 years and you began with 10 g, how much strontium would be left after 3 half lives. 10g x (1/2) 3 = 10g x 1/8 = 1.25 g left after 29x3 yrs (87 yrs)

12. Half-Life Problems 1. If gallium-68 has a half-life of 68.3 minutes, how much of a 10.0 g sample is left after one half-life? two half lives? 2. If the passing of five half-lives leaves 25 mg of a Sr-90 sample, how much was present in the beginning?

13. Radiochemical Dating radiochemical dating: determining the age of an object by measuring the amount of a certain radioisotope remaining in an object. -carbon dating: measure age of artifacts that were once living ▪C-14’s half-life = 5370 years -uranium dating: measure the age of rocks ▪U-238’s half-life = 4.5x10 9 years

14. Fission and Fusion fission: splitting of a nucleus into fragments, accompanied by a very large release of energy -creates a chain reaction, a self-sustaining process in which one reaction initiates the next -nuclear power plants During fission energy is released, about 3.2 x 10 -11 J. By comparison, TNT releases about 4.8 x 10 -18 J

16. http://www.allforpower.com/clanek/380-welding-the-components-of-nuclear-power-plants/ http://geosci.uchicago.edu/~moyer/GEOS24705/ http://clearlyahead.com/energy-department-2/wind/how-it-works/ http://www.sommersgen.com/basics/about-generators.php

17. 17 Benefits to Nuclear Power 1. does not produce gaseous pollutants that cause ozone depletion and acid rain 2. more energy in the known uranium reserves than in the known reserves of coal and oil 3.eventually we will use up the coal and oil 4.cost to produce it is cheaper than for coal

18. 18 Dangers to Nuclear Power 1. radioactive products must be handled correctly 2. safety of the reactors -equip with shielding 5. expensive to build 4.can only be operated for 40 years (license can renew for 20 more years) -after shut down, decommission must occur w/in 60 yrs 3.storage of nuclear waste -sparsely populated area with little surface/ground water, free from quakes - must store for 1000s of yrs

19. HW Find 2 pros and 2 cons to using coal burning plants, hydroelectric plants and wind power plants.

20. fusion: combining of atomic nuclei, releasing very large amounts of energy -sun undergoes fusion -very hard to contain and control

21. 21 Power from Fusion Nuclear Fusion reactors are being tested -difficult to produce in the laboratory -never been produced in a power plant -far from reality: a)it can produce a dangerous form of nuclear radiation (neutrons) b) shielding materials would need to be replaced periodically due to the high temp needed

22. Nuclear Reactions Review 1.How do unstable atoms gain stability? 2.How does a nuclear reaction differ from a chemical reaction? 3.Determine what type of decay occurs when Th-231 undergoes radioactive decay to form Pa-231. 4.Complete the following nuclear equations: a. ?  222 Rn + 4 He b. 66 Cu  66 Zn + ? 86 2 29 30 5. How can you predict if an isotope is unstable? 6. Using the half-life in Table 25-5, how much of a 1.0g polonium-214 sample is left after 818 microseconds? 7. Describe the process that occurs during a nuclear reaction.

23. Intro to Radiation Lab: Pre-Lab 1.What do the nuclear properties of an atom depend on? 2.What is radioactivity? 3.When does the emission of the nucleus generally occur? 4.What is half-life? 5.Why is knowing the half-life useful? 6.What are the qualitative methods of detecting the emission of radioactive isotopes? 7.What are the quantitative methods of detecting the emission of radioisotopes? 8.How does the nuclear scaler record the amount of radiation emitted?