i. transmutation transmutation - the conversion of one element to another element. all nuclear...
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Post on 21-Dec-2015
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- I. Transmutation Transmutation - The conversion of one element to another element. All nuclear reactions are transmutation reactions except for gamma emission, which does not alter an atoms atomic number.
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- II. Induced Transmutation Before 1919, the only way to change the nucleus or cause transmutation was to wait for nature. In 1919 Rutherford was the first to induce (cause) transmutation. He proved that nuclear reactions can be produced artificially. Induced transmutation can occur by bombarding an atom with alpha particles, protons or neutrons.
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- III. Transuranium Elements Elements with atomic number above 92. All transuranium elements undergo transmutation None of the transuranium elements occur in nature and have been produced through induced transmutation.
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- IV. Half-life The time required for one-half of a radioisotopes nuclei to decay into its products After each half-life, half of the existing radioactive atoms have decayed into atoms of a new element Amount remaining at time T = (initial amt)(1/2) n where n= number of half-lives n = total time time of one half-life
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- Half-Life Skip count 50.0 g25.0 g12.5 g6.25 g3.125 g3.13 g 123 4 Practice 1.Scientists start with 50.0 g sample of a radioisotope. How much is left after four half-lives?
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- 2. Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of iron 59 is 44.5 days. How much of a 2.000 mg sample will remain after 133.5 days? (first find out how many half-lives, then skip count)
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- Half-Life Skip count 2.000 mg1.000 mg0.5000 mg0.2500 mg 123 133.5 days 44.5 days = 3 half-lives
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- V. Carbon-14 Dating Carbon 14 dating is the process of determining the age of artifacts that were once part of a living organism by measuring the amount of 14 C remaining in that artifact Carbon-14 is radioactive and undergoes beta decay. It has a half-life of 5730 years.
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- Carbon-14 14 C evenly spread in the Earths biosphere Plants incorporate 14 C into their structure that matches the level in the atmosphere. When an organism dies, 14 C declines at a known rate. (Half-life of C-14 = 5730 years) Comparing the remaining 14 C fraction of a sample to that expected from atmospheric 14 C allows the age of the sample to be estimated. Dates carbon-bearing materials up to 62,000 years.
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- Carbon-14 Decay Using the graph, about what % of carbon-14 remains after 11, 400 years?
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