BIOLOGICAL SCIENCE 102 – ANIMAL BIOLOGY
– VOCABULARY & NOTES
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RADIOMETRIC DATING
ISOTOPE
= an element with a different number of neutrons as compared to the parent element
RADIOACTIVE ISOTOPE
= an isotope that gives off energy and decays into another isotope
A breakthrough came with the discovery of radioacticity at the beginning of the 1900s.
Scientists discovered that rocks could be timepieces -- literally. Many chemical elements in
rock exist in a number of slightly different forms, known as isotopes. Certain isotopes are
unstable and undergo a process of radioactive decay, slowly and steadily transforming,
molecule by molecule, into a different isotope. This rate of decay is constant for a given isotope,
and the time it takes for one-half of a particular isotope to decay is its radioactive half-life. For
example, about 1.5 percent of a quantity of Uranium 238 will decay to lead every 100 million
years. By measuring the ratio of lead to uranium in a rock sample, its age can be determined.
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- Spring '08
- B
- Biology, Radioactive Decay, Chemical element, Isotope, radioactive carbon dioxide
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