VIEWS: 1 PAGES: 7 POSTED ON: 5/9/2013
Radioisotope Dating What is radioactivity? • Radioactivity is the spontaneous emission of energy from unstable atoms. • There are stable atoms, which remain the same forever, and unstable atoms, which break down or 'decay' into new atoms. • These unstable atoms are said to be 'radioactive', because they emit radioactivity from the nucleus as they decay. What is radioactivity? • Radioactivity is a random process that happens naturally as the isotopes in particular elements decay. • The isotopes continue to break down over time. – The length of time that is taken for half of the nuclei in an element to decay is called its 'half-life'. What is the connection with exponential decay? • The radioactive half-life for a given radioisotope is the time for half the radioactive nuclei in any sample to undergo radioactive decay. • After two half-lives, there will be one fourth the original sample, after three half-lives one eight the original sample, and so forth. Dating the Dead Sea Scrolls • We date the Dead Sea Scrolls which have about 78% of the normally occurring amount of Carbon 14 in them. • Carbon 14 decays at a rate of about 1.202% per 100 years Years after % Carbon remaining death 0 100 100 =B2-0.01202*B2 200 . . Dating the Dead Sea Scrolls • Do excel example Dating the Dead Sea Scrolls • We find that the Dead Sea Scrolls would date from between 2100 to 2000 years ago. • Current estimates are that a 95% confidence interval for their date is 150 BC to 5 BC.
Pages to are hidden for
"Radioisotope Dating"Please download to view full document