Nuclear Chemistry

Regular chemical Reactions electrons do all the work atom identity is unchanged energy is involved Nuclear Reactions Nucleus (protons and neutrons are involved) atom identity changes!! HUGE energy is involved

Proton +1 1.000000 amu

Electron -1 0.001837 amu

Neutron 0 charge 1.001837 amu

Proton Electron Neutron -1 +1 0 charge 1.000000 amu 0.001837 amu

In the following illustrations: N = a neutron P = a proton

N P

N N P N P N P N P N P N N P P N

C Sn Pb Si Ge (These are all Group 14 elements) Protons Neutrons Protons Neutrons N P 12 C 119 Sn 6 50 N P N P P N P N N P P N P N P N N 207 N P Pb 28 Si N P P P N N P N P 82 14 (These are all Group 14 elements) 73 Ge 32 (Note: small nuclei are often stable when they have the same number of protons and neutrons. As the nuclei get bigger, they need a larger proportion of neutrons. Above 82 protons, lead, all nuclei are unstable, and are thus radioactive.)

U (An unstable atom can emit an alpha particle to become more stable) Protons Neutrons 238 92 (An unstable atom can emit an alpha particle to become more stable)

U (an alpha particle, aka a helium nucleus) Protons Neutrons Protons Neutrons 238 U N N N P P P 92 P N N N N N N N P N N P P N P N P P N N N N P P N N N P P P N P N N N N N P P P N P N N N N P P N P P P N N P P P N P N N N N N N P N N N P N N P P N N N P P P N P P N N N N P N P N N N N N N N N N P N P P P N N P P P N N P N N P N N N N N N N N P N P N N P N P N N P P N P N N (an alpha particle, aka a helium nucleus) N P P N N P N N N N N N P N N P N P P N P P N N N P N N P P N P N N N P N N N N N P P P N N N P N N P P P N P N N P N P N P N P N N N P N N P N P N P P N N N N P N N P 234 (Losing 2 protons and 2 neutrons results in a change to a Thorium atom, Th) 90

Protons Neutrons U 92 238 N N N P P P N N P N N N N N P N N N P P N P P N P P N N N P P N P N P P N N N N N P P P P N N N N N N N N P P P N N P N P P N P N N N N P N P P P N N N N P N N N P P N N P P P N P P N N N N P N N N P N N N N N N N P N P N P P P P N N P N N P N N N P N N N N N N N N P N N P N P N N P P N P N P N P N N N N P N P P N P N N N N N N N N N P N P N P P P N N N P P N N P N P P N N P N N N N N N P P P N N N P N P N P P P N N N P N N N N P N P N N N P P P N P N P P N N N N P N N P (Or an unstable uranium atom can convert a neutron into a proton by spitting out an electron, a beta particle)

Protons Neutrons U 92 238 N N e N P P P N P N N P N N N P N N P P P N P N P N N N N P P N P N N N P P P N N N P P P P N N N N N N N N P P P N P P P N P N N N P N N N P P N P N N N N P P N P N P P N P N N N N P P N N (Note: this high energy electron, the beta particle, comes from the nucleus, not the electron cloud) P N N N N N N P N N N N N N P N P P N N P P P P N N P N N N P N N N N N N N N P P N N N P N P N P N N P N P N P N N N P P P N N P N N N N N N N N P N N P N N P P N P P N P N P N P N P N N P N N N N P P P N N N N P P P N N P N P N N N P N P N P N N N P N N N P P N P P N P N N N N P N N P 238 (Since the atom now has one more proton, it is now neptunium, Np) 93

Gamma radiation. Gamma radiation is merely energy (an electromagnetic wave) that is given, often accompanying alpha or beta radiation. It is not a particle at all.

NUCLEAR CHEMISTRY - Radioactivity & Radiation - Alpha, Beta, Gamma.mp4

Radiation Notes Types of Radiation Ionizing radiation have high energy and "ionize" the atoms they hit alpha, beta, gamma Non-ionizing radiation low energy TV, radio, microwave, light, etc.

Ionizing Radiation Sources Radiation Notes Ionizing Radiation Sources the earth, dirt and rocks bricks and concrete space Xrays smoke detectors

Radiation Notes Radiation and Health Adverse Effects overexposure leads to radiation sickness and death (hours to weeks). Body functions stop lesser amounts affect living cells and MAY result in cancers and chromosomal mutations, which may lead to birth defects "Background radiation" (the normal radiation exposure from space and the environment) damages cells but our bodies can normally repair Individual tolerances vary a

Radiation Notes Radiation and Health Beneficial Effects Radioactive TRACERS can be used to detect diseases, abnormalities and cancers Controlled radiation can stop and kill some cancers. BUT the radiation also kills normal cells. Strategies: Carefully target only cancer areas Because cancers often can't repair themselves as well as normal cells, use doses that kill the cancer cells but don't overwhelm normal cells.

Radioactivity test today! Omit: Version A: 8, 9, 18, 19 Version B: 1, 2, 3, 4

Nuclear Chemistry Radioactivity: small pieces (eg alpha, beta) are emitted Fission: a large atom splits! Fusion: two small atoms (like H) combine (fuse) to from a larger (He).

Nuclear Fission When hit by a neutron, an unstable nucleus SPLITS, forming two smaller nuclei and releasing more neutrons. These neutrons hit more unstable nuclei resulting in a CHAIN REACTION. This is the type of nuclear reaction that is used in all nuclear power plants.

Nuclear Fission U Kr + + Ba (and a heck of a lot of energy!!) N P N N Protons Neutrons P N Kr N + + N N N P N Ba (and a heck of a lot of energy!!)

Smaller nuclei FUSE to form a larger nucleus. H + H He Nuclear Fusion Smaller nuclei FUSE to form a larger nucleus. H + H He Takes place on the sun and is the source of the sun's energy and thus of all life on earth!!!

Nuclear Fusion H + H He (and a heck of a lot of energy!!) P N N P N P

Comparing Fission and coal for producing energy

Comparing Fission and coal for producing energy Advantages of Fission: environmental and health impacts of nuclear power plants are minimal compared with coal-fired power plants fission reactions produce no air pollution or the greenhouse gas CO2 a 1000 megawatt nuclear reactor uses 25 tons of fuel a year (and 25 tons of radioactive waste). A comparable coal-fired plant uses 2.5 million tons of fuel per year and produces millions of tons of CO2, SO2, and nitrogen oxide compounds (which contribute to acid rain)

Comparing Fission and coal for producing energy Disadvantages of Fission: nuclear plants are exceedingly EXPENSIVE to build radioactive waste is generated that may cause long-term health problems, lasts virtually forever, and requires disposal that is difficult and controversial although the potential for a nuclear accident is small (compared with coal plants), such an accident could cause catastrophic loss of life and property.

Comparing Fission and Fusion for producing energy Fusion reactions produces 20 times the energy of fission for the same mass of fuel. Fusion fuel, hydrogen, is very abundant and safe, unlike the uranium or plutonium used for fission Fusion reactions do not produce radioactive products or air pollution Fusion reactions are easier to control, reducing the risks of fires and explosions BUT because it takes milliions of degrees to start a fusion reactor, we have, thus far, been able to get more energy out than is needed to start the reaction. Intensive research is underway.

Final Exam Answers re Fission and Fusion 135. 136 - 147. Nuclear fission is the process by which a single large nucleus breaks apart into two smaller nuclei. Three different products form in any nuclear fission reaction are smaller nuclei, neutrons, and energy. Two major concerns people have about nuclear reactions are the possibility of nuclear accidents and the issue of how to dispose of nuclear waste. Nuclear fusion is the reaction that occurs when two small nuclei join together to form a larger nucleus. The sun's energy is produced when hydrogen nuclei fuse to make helium nuclei. Although fusion is cleaner, safer, and more efficient than fission for producing energy, it is not currently used to produce energy because of the large amount of heat required to start the reaction.

Whew! I'm done teaching chemistry for the year! (Your heads must be really full)

What to do now... Work on final review packet Work on cheat sheets

Attachments NUCLEAR CHEMISTRY - Radioactivity & Radiation - Alpha, Beta, Gamma.mp4