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24 Cards in this Set
- Front
- Back
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nuclear stability |
nuclear force -nuclear force ---stability comes from ---strong ---at very short distances |
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Shell Model of the nucleus |
-is a nuclear model in which protons and neutrons exist in levels or shells |
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A magic number |
-is the number of nuclear particles in a completed shell of protons and neutrons |
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For protons |
-2, 8, 20, 28, 50 and 82 |
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for neutrons |
-also include 122 -for stable nuclides w/z < or equal to 20 -ratio of neutrons to protons is between 1 and 1.1 w/z >2.0, ratio increases to ~1.5 -w/z >83 : no stable nuclide exists |
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radioactive decay |
because its constant, this rate can serve as a sort of clock for datng objects ex: carbon-14 is part of all-living material -half life 573 venzs -decay for 15.3 dsintegrations per min. per gram of total carbon |
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radioactive decay series |
-A sequence in which one radiactive nucleus decays to a second, which then decays to a third, and so forth, until a stable nucleus of lead is formed |
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radiation and matter |
-dissipation can ionize atoms and molecules, and in some cases, excite in matter -when these electrons undergo, transitions to grand stants --light is switched --because nuclear radiations can form ions and break chemical bonds ---->Adversely affect biological organisms |
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radiation counters |
1) Ionization counter -Geiger counter -Count particles emitted by radioactive nuclei 2) Scintillation counter -Detects nuclear radiation based on flashes of light generated in a material by the radiation |
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biological effects and radiation dosage |
-rad (Radiations affects dose) --deposits 1x10^-2 J of energy per kg of tissue --rem radiation dosage is useto various kinds of radiation-->biological distruction |
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rem=vadxRBE |
relative biological Effectiveness --beta+Gamma BBE~1 nuetron is radiation RBC~5 alpha radiation RBE~10 |
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Effect of radiation on a person |
-a person depends on dosage and length of exposure --single dose to 500mms fatal to mass people --30mms directable effect -1rmm rate |
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rate of radiation decay |
-# of nucluei disintegrating per unit time Rate=KNE -k is rate -E is pi of radioactive nucleus of time, t |
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Half life |
-the time it takes for one-half of the nuclei into a sample to decay --After on half life ----half of sample remanats --After 2 half lives, -----one-fourth simple remaining --After 3 half lives -----One-eighth sample remaining Fraction Remaining= (1/2)^n |
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Radioactive tracer |
-small amount of radioactive isotope tat is added to a chem., bio., or physical system so as to study the system ex: isotope dilution -determine QTY of substance on a mixture |
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Nuetron activiation analysis |
analysis of element in a sample based on conversion of stable isotopes to radioactive isotopes by bombarding sample w/neutrons |
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Medical therapy + diagnosis |
100+ different radioactive isotopes |
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Radioimmonoassay |
-analyze your blood or other bodily fluids for presence of very small quantities or biologically active substances |
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nuclear fission |
nuclear reaction in which a heavy nucleus splits into lighter nuclei + releases energy |
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nuclear fussion |
nuclear reaction in which light nuclei combine to give a more stable, heavier nucleus, plus possibly several nuetrons -releases energy |
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nuclear chain reaction |
-self-sustaining series of nuclear fissions causes by the absorption of nuetrons released from protons nuclear fissions |
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critical mass |
to sustain a chain RXN in a sample of fissionable material, a minimum amount of the particular fissionable material is needed |
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nuclear fission reactor |
permits a controlled chain RXN of nuclear fission |
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For the nuclei to react, |
bombarding nuclei must have enough kinetic energy to overcome repulsion between positive nuclei |
