Half-life of Radioactive materials & nature of nuclear radiatiors 0.0 / 5 ? PhysicsRadioactivityGCSEWJEC Created by: Katy **Created on: 03-01-14 17:11 Atoms Nucleus: protons → mass = 1 (+1) neurons → mass = 1 (0) Orbits: electrons → mass = negligble (-1) 1 of 6 Radioactive Elements / atoms with an imbalance between the no. protons & no. neutrons. Elements / atoms that have a nuclei larger than Lead = unstable. When they give off radiation they become - ◘ more stable ◘ may change to other elements 2 of 6 Radioisotopes Iosotpe of an element has: same no.protons different no. neutrons Radioisotopes are isotopes that are radioactive. 3 of 6 Measuring Radioactivity Measurements allow for: randomness of decay - measure over a long time (average) background radiation - measure background radiation & subtract Unit - becquerel (Bq) 1 disintergration per second 4 of 6 Half-life Time taken for: activity of sample to reduce to half its initial amount no. sunstable nuclei to reduce to half initial amount Nothing can change the half-life of an isotope (not thermal / chemical / physical) Half-life varies from seconds → years shorter half-life = more unstable more radioactive isotope = shorter life 5 of 6 Uses of Radioactive material Domestic: smoke alarms (alpha) → stopped by smoke (10yrs half-life) Archaeology: carbon 14 dating → natural ratio of carbon in living things Industrial: leaks from gas water pipes (gamma) → to source & check for radiation (days half-life) Medical: steralising equipment → iteam radiated = destroy bacteria (gamma) cancer treatment → external (gamma) - destroys cancer cells internal (beta & alpha) - to site = control & high ionising (24 hours half-life) tracers → radiation & time to collect & monitor (not alpha as kill patient & high ionising) labelled material → (not beta as detected & ionising) 6 of 6
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