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24 Cards in this Set
- Front
- Back
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mass is...
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NOT conserved in nuclear reactions
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....is conserved in nuclear reactions
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atomic and mass number
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alpha particle
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He, 2 protons and 2 neutrons
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beta particle
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0 mass, -1 charge (+1 atomic number)
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positron emission
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0 mass, +1 charge (-1 atomic number), electron with positive charge
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electron capture
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0 mass, +1 charge (-1 atomic number, nucleus captures electron in lowest energy level
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gamma
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accompanies all emissions, high energy
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...determines stability
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neutron to proton ratio
1.5:1 or 1:1 |
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if ratio > than allowed...
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beta negative emission (atomic number +1)
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gamma penetration
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very dangerous, stopped by thick lead/concrete
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alpha penetration
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stopped by paper or skin
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beta penetration
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stopped by aluminum foil or thin wood
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transmutation
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spontaneous emission to make a new, more stable element (natural or induced: transuranium elements- 93 to 95)
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Henri Becquerel
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discovered radioactivity, radiation is produced spontaneously by unstable nuclei
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Roentgen
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discovered x-rays in 1985
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Marie and Pierre Curie
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showed that uranium is the source of radiation; isolated radium and polonium
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half life
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amount of time for substance to become half its size
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nuclear fission
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large atom splits into two smaller nuclei and gives off neutrons (to bombard other nuclei); produces radioactive material, and energy for electricity
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nuclear fusion
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when two smaller atoms sombine to make one more stable element, need HIGH energy (40 million Kelvin), fission energy used to fuel fission, nonradioactive products, produces 10 times more energy than needed
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neutron moderators
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slows down neutrons let off by fission reaction so they can be caught by neutron absorbers (Cd rods) to prevent atomic BOMB!
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if ratio < than allowed...
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positron emission or electron capture
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ionizing radiation
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from x rays and radioisotopes; radiation energetic enough to ionize matter it collides with
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detecting radiation...
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geiger counter (beeps if radiation present); film badges (has radiation sensitive film to moderate radiation exposure); scintillation counter (number and brightness of scintillations measure radiation)
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uses of radiation...
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radiotracers (non ionizing radiation to detect substances) in industry, medicine, PET, radiation therapy)
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