EARTHSC 1121 Lecture 6: 1/26
9 Feb 2017
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Finishing up on the age of the earth; starting up on the structure of the earth. Variants of a chemical element that differ by the number of neutrons in the nucleus. The number of protons is the same and two isotopes of an element behave identically to one another chemically. Carbon-12 = carbon with 12 things in the nucleus. Carbon dating = an experimental technique comparing carbon-14 to carbon-12. Parent isotope decays to a daughter isotope. Potassium-40 (most is potassium-39 and is not radioactive as a stable element). We have all consumed radioactive potassium-40 if we have eaten a banana. It is a small amount though, so harmless. Every radioactive element has a characteristic time for decay: half life . After the amount of time of that half life has passed, half of those radioactive. N0 = number of atoms at a time (t) = 0 t time for the number of atoms to be half n0.
