Warm Up 10-12-17 Why are some isotopes radioactive? Ultraviolet have longer wavelength than gamma ray, which radiation is worst? Can radiation be good? 1. 2. 11.25 grams after 3 half-life 3. Yes proton therapy https://www.youtube.com/watch?v=OTd5dv3VDws http://www.proton-therapy.org/howit.htm Agenda -Notes Unit 3-5 -Worksheet nuclear decay Homework Oct 24 – Xtra Credit due

Unit 3-5 Characteristics of Nuclear Decay

Characteristics of Some Radiation Alpha- weakest, a thin barrier can stop (they are big and heavy and can’t travel very far) Beta- clothing, wood, or aluminum can stop this radiation. Alpha - -when inhaled or ingested can be dangerous. Alpha particle decay use in smoke detector, pace maker and space probes Gamma is most dangerous (atomic bomb) wear a lead vest when taking dental x-rays https://www.youtube.com/watch?v=phZeE7Att_s carbon dating video Discuss with your partner - differences between the three radiation Gamma- highly energized can be stop by concrete or lead

Alpha Decay Problem: the nucleus has too many protons which cause excessive repulsion. Solution: In an attempt to reduce the repulsion, a Helium nucleus is emitted.

Alpha emission (decay) 4 2 He Identify the product formed when uranium-238 alpha decays 4 2 He + 234 90 Th 238 92 U Determines which atom from the periodic table

Beta Decay Problem: too many neutrons not enough protons. Solution: a neutron is turned into a proton and one electron is then ejected. Neutron is converted into proton, and a electron is released

0 -1 e + 14 7 N 14 6 C beta emission (decay) 0-1 e Identify the product formed when carbon-14 emits beta particle 0 -1 e + 14 7 N 14 6 C

Gamma Decay Problem: the nucleus is at too high an energy. Solution: The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma ray. Emphasis that the energy released is photon (wavelength) not heat, flame test lab electron losing energy, this is the nucleus losing energy photon = gamma ray instead of visible light (red, green, etc…)

gamma emission (decay) 00 γ Identify the product formed when carbon-14 releases gamma rays 0 0 γ + 14 6 C 14 6 C Discuss cancer, what is it, diagnosis, treatment? https://www.youtube.com/watch?v=OTd5dv3VDws photon therapy

Assignments Summary: Why is alpha weaker than gamma radiation? What’s the difference between bad and good radiation? Nuclear decay worksheet (at least the front page is done before leaving class) - due next class check answers on my website Good radiation = proton therapy, controlled and directed at the tumor Chemotherapy = drugs to control the tumor from growing

Summary of Radiation Alpha radiation: consists of He nucleus 23892 U  42 He + 23490 Th Beta radiation: electrons formed by the decomposition of a neutron 146 C  0-1 e + 147 N Gamma radiation: high energy electromagnetic radiation; often emitted with alpha or beta radiation http://www.youtube.com/watch?v=oFdR_yMKOCw – radioactive decay

Summary of Radiation Property Alpha radiation Beta radiation Gamma radiation Composition Alpha particle (He nucleus) Beta particle (electron) High energy EM radiation Symbol , 42 He , 0-1 e  Penetrating power low moderate Very high Shielding Paper, clothing Metal foil Lead, concrete