2007-09-16 15:52:37 · 4 answers · asked by laurenjade11 2 in Science & Mathematics ➔ Biology
Carbon 14 is used for radioactive dating.
It works well because all life on Earth is carbon based.
Carbon 14 decays at a known rate so the amount of carbon 14 left in a sample will determine the items age. Carbon 14 was created when the earth was first formed so the amount of it is constant and it decays at a known rate. However, that does limit the time range that you can work over; "in the range between 58,000 and 62,000 years (approximately 10 half-lives). This limit is encountered when the radioactivity of the residual 14C in a sample is too low to be distinguished from the background radiation. (source listed below)"
According to Wikipedia: http://en.wikipedia.org/wiki/Carbon_dating
"Radiocarbon dating is a radiometric dating method that uses the naturally occurring isotope carbon-14 (14C) to determine the age of carbonaceous materials up to about 60,000 years. Raw, i.e. uncalibrated, radiocarbon ages are usually reported in radiocarbon years "Before Present" (BP), "Present" being defined as AD 1950. Such raw ages can be calibrated to give calendar dates.
The technique of radiocarbon dating was discovered by Willard Libby and his colleagues in 1949 during his tenure as a professor at the University of Chicago. Libby estimated that the steady state radioactivity concentration of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram. In 1960, he was awarded the Nobel Prize in chemistry for this work."
2007-09-16 16:02:30 · answer #1 · answered by Dan S 7 · 2⤊ 2⤋
The property that allows them to be used to determine the age of rocks and fossils is that they decay at a known and constant rate. Every radioisotope has a half-life; that is, a period of time during which half of its nuclei will decay into more stable nuclei. If you know a radioisotope's half-life, and if you know how much of it was originally present in a sample, you can tell how long the sample has been decaying based on the fraction that remains. Now if you want to learn about how scientists determine how much of a radioisotope was originally in a sample, that's a whole other question.
2007-09-16 16:09:19 · answer #2 · answered by Lucas C 7 · 1⤊ 0⤋
They have a constant rate of decay that can be used to calculate the age of the item. this is known as there halflife.
2016-05-21 06:19:39 · answer #3 · answered by verdie 3 · 0⤊ 0⤋
Wow. Trying to answer your homework?
Um...
Chapter 2: The Chemistry of Life | Section 2-1
Uh-huh...
2007-09-19 16:33:30 · answer #4 · answered by The Savage 2 · 1⤊ 6⤋