Significant progress has
been made in this field of study since the discovery of radioactivity and its
properties. One application is carbon-14 dating. Recalling that all
biologic organisms contain a given concentration of carbon-14, we can use this
information to help solve questions about when the organism died. It works like
this..when an organism dies it has a specific ratio by mass of carbon-14 to
carbon-12 incorporated in the cells of it's body. (The same ratio as in the
atmosphere.) At the moment of death, no new carbon-14 containing molecules are
metabolized, therefore the ratio is at a maximum. After death, the carbon-14 to
carbon-12 ratio begins to decrease because carbon-14 is decaying away at a
constant and predictable rate. Remembering that the half-life of carbon-14 is
5700 years, then after 5700 years half as much carbon-14 remains within the
organism.
Example : If an organism such as a tree contained 1 gram
of carbon-14 while it was living, then after 5700 years it would contain half
that amount, or 0.5 grams of carbon-14.
This method of dating using carbon-14 is only good for
organisms or artifacts that are biological by nature and on the order of tens of
thousands or years old.
What isotope would be increasing due to the decay of
carbon-14?
Could this method of dating be used to estimate the age of
petroleum deposits?
What human activities could alter the carbon-14/carbon-12
ratio?
You Tell Us:
Check to see if any local archeological activities are in progress is
your community. What has been discovered? Can carbon-14 dating be used
to estimate the age of the artifacts? |
Original source of page: http://www.chem.duke.edu/~jds/cruise_chem/nuclear/dating.html
