radioactivity part 2 nuclear chemistry. three types
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Radioactivity Part 2Nuclear Chemistry
Alpha RadiationPolonium-210 is an alpha emitter. During radioactive decay, it loses two protons, and becomes a lead-206 atom, which is stable (i.e., nonradioactive).UsesRadium-226 to treat cancerPolonium-210 eliminates static in paper mills by alpha particles attracting loose electronsAmericium-241 in smoke detectors to help create electrical current (smoke will interrupt the current and set off the alarm)Found in NatureRadium-226 & Uranium-238 are present in all rocks, soil, waterMining tends to increase exposure in humans & the environmentEffectsLack energy to penetrate skin (must be inhaled, ingested, absorbed)Greatest hazard to lung tissue (inhaled)Inside us its the most dangerous (Causes cancer)
Human Exposure to RadioactivityRadon (Radioactive Gas) is part of the radioactive decay chain of naturally occurring uranium in soil.You cant see, smell or taste radon. Health effect = lung cancer Test every 2 years Above 4.0 pCi/L of radan in the air should be dealt with.
important for the management/disposal of radioactive materialsDuring decay Radon-222 is commonly produced. Its a gas and seeps up through the soil into the air. It can accumulate into high concentrations in basements. Gives off alpha particles Its short half life means it emits alpha particles at a high rate.
Beta RadiationUsesIodine-131 to treat cancerStrontium-90 is a tracer in medical & agricultural fieldsTritium used for luminous exit signs, dials and watchesCarbon-14 for dating organic matterFound in NatureCarbon-14 & Potassium-40 found in our bodiesEffectsLack energy to penetrate solid materialDirect exposure can redden or burn the skinKills cellsIodine-131 accumulates in the thyroid glandStrontium-90 accumulates in bone and teeth
Gamma RadiationUsesCesium-137 cancer treatment, measurements (soil density, packaging, oil wells)Cobalt-60 sterilize medical equipment, treats cancer, pasteurizes foods and spices, measures thickness of metalsTechnetium-99 used for medical imaging (xrays)Can inspect welds and metal parts for leaks and defectsFound in NaturePotassium-40 found in soil and water, meats and foods high in potassium like bananasEffectsCan improve durability of wood and plasticsRadiation sickness
*Your annual Radiation DoseAverage annual radiation dose in US is 360 mrem. The normal permissible limit is 5,000 mrem for those who work around radiation.
*Radiation DetectionApproximate amounts of radiation can be detected by the following devices:Film badgeGeiger-Muller counterScintillation counter
Half-life Half-life time required for half of the original sample of radioactive nuclides to decay Half of the radioactive parent atoms decay after one half-life. Half of the remainder decay after another half-life and so on..
Half lifeThe decay of radioisotopes can be used to measure the materials age. At start there are 16 radioisotopesAfter 1 half life half have decayed (thats 8)After 3 half lives another 2 have decayed (14 altogether)After 2 half lives another half have decayed (12 altogether)
Decay Curveshows the decay of radioactive atoms and the remaining radioactive sample.
A very important point here is that we cannot predict when a particular entity will decay. We do know though, that if we had a large sample of a radioactive substance, some number will decay after a given amount of time. Some radioactive substances have a very high rate of decay, while others have a very low decay rate.
Application of Half LifeRadioactive dating a process used to determine the approximate age of an object.
Ex. Carbon -14, a radioactive isotope is in all living things. When organisms die Carbon-14 decreases and can estimate how long something has been dead.Video http://www.youtube.com/watch?v=phZeE7Att_s
Application of Half LifeIodine-131, a radioactive isotope, is injected into the body to treat thyroid cancer.Its half life is 8 days this tells us the rest will disappear in 80 daysGood because it will be active long enough for a cancer treatment, but should be short enough not to do more damage to healthy cells and organs.*
Videoshttp://www.youtube.com/watch?v=27qSAqafQ6oAlpha, Beta, Gamma http://youtu.be/5oUagoF_viQAlpha http://www.youtube.com/watch?v=j5TJRtJxVfsBeta http://www.youtube.com/watch?v=rW0A5FZTxt0 life -http://youtu.be/tzM6aK5QbSUhttp://www.youtube.com/watch?v=xhOtKurHayoCarbon dating
Nothing really stops it but lead or concrete can slow it down**http://www.scientificamerican.com/video.cfm?id=how-does-radiocarbon-dating-work--i2012-11-30