Radioactivity January 2015 Recall Isotope Notation Why are

Radioactivity January 2015

Recall Isotope Notation • Why are some isotopes radioactive? • How do you find the number of neutrons? • What is alpha, beta, gamma decay?

Nuclear Reactions- Fission and Fusion • Why are some nuclei unstable? • In the nucleus, P+ and N ﹾ are held together by the strong nuclear force (SNF) • Protons having the same electrical charge “repel” each other. • SNF must overcome this repulsion for the nucleus to hold together • (Small nucleus: SNF > repulsion …= stable • Large nucleus: SNF and repulsive force are similar strength… =unstable) • All nuclei with 83↑ protons are radioactive.

Fission (Division) • Fission (division): a large nucleus is broken into smaller nuclei. Or a more massive nucleus forming 2 less massive nucli • The nucleus is bombarded by a particle… (n )ﹾ • When the nucleus splits, it releases n ﹾ and Energy • Can lead to a chain reaction. • Uncontrolled = bomb • https: //www. youtube. com/watch? v=q. T 4 m. So. Zsbz. M

Fission (Division) • Controlled = nuclear power plant • https: //www. youtube. com/watch? v=MGj_a. Jz 7 c. Ts • https: //www. youtube. com/watch? v=_Ad. A 5 d_8 Hm 0 • Nuclear power plants use fission of Uranium atoms to generate electricity. • Pros- use small mass to generate a lot of energy • Cons • While it does not produce a lot of waste it produces other pollution such as radioactive material and using lakes and rivers to cool reactors leading to thermal pollution • the half life of Uranium is… Thermal Pollution https: //www. youtube. com/watch? v=d. Ljow _j. Zj. LA (power plants

• Critical mass: smallest possible mass that can sustain a nuclear reaction

Fusion • Fusion: Small nuclei combine to form a larger nucleus. • Releases lots of E • Occurs at very high temperatures… 10, 000 ﹾ C, this is why it is not yet suitable for energy production • Our sun and most stars are fusion reactors • http: //www. youtube. com/watch? v=f. Sr 3 V 498 A 3 I&feat ure=related (animation) • http: //www. youtube. com/watch? v=s. Si-z. Se. S 0_YRates (Torus Facility)

Benefits of Radioactivity • Nuclear power generates electricity • Radioactive tracers used to follow chemicals through living organisms and the environment (groundwater)

Benefits of Radioactivity • Medical imaging: PET scans, autoradiography, etc. . .

Benefits of Radioactivity • Cancer treatment • Detection …smoke detectors, explosives in luggage, leaks in pipes, location of underground conduit, moisture content of soil, etc… • Foods are preserved by radiation…spices and dried fruits/vegetables are irradiated to destroy pathogens. Potatoes and onions are irradiated to retard their sprouting. Fruits and vegetables are irradiated to slow down the ripening process. • Used to control the thicknesses of paper, plastics, metal foil • Radiometric dating of ancient objects

Radiation Dangers • Damages/destroys cells…. Red blood cells lose ability to carry oxygen, burns the skin, causes cataracts, destroys bone marrow cells, genetic mutations (damages DNA) which can lead to birth defects, etc… • High doses/prolonged exposure = radiation sickness = hair loss, sterility, bone deterioration, cancer, death, etc…

Nuclear Power Plants: Pros and Cons • No pollutants released during the electricity production(compared to coal or natural gas power) • No dams on rivers interrupting natural aquatic ecosystems (compared to hydroelectric power) • Risk of a melt down causing radioactive matter to be released into the environment • Problems storing the nuclear waste (Radioactive Daughter Isotopes) • https: //www. youtube. com/watch? v=m. Febo. B 2 u 3 QI -Darlington Pros/Cons • https: //www. youtube. com/watch? v=vnjz. VNG 18 jo- Chernobyl • https: //www. youtube. com/watch? v=k. Bmc 8 SQMBj 8 - Fukishima