08 Apr

However, once the atom reaches a stable configuration, no more radiation is given off.For this reason, radioactive sources become weaker with time.

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source radiocarbon dating A technique for measuring the age of organic remains based on the rate of decay of carbon 14.

If you could watch a single atom of a radioactive isotope, U-238, for example, you wouldn’t be able to predict when that particular atom might decay.

It might take a millisecond, or it might take a century. But if you have a large enough sample, a pattern begins to emerge.

Because the ratio of carbon 12 to carbon 14 present in all living organisms is the same, and because the decay rate of carbon 14 is constant, the length of time that has passed since an organism has died can be calculated by comparing the ratio of carbon 12 to carbon 14 in its remains to the known ratio in living organisms. Our Living Language : In the late 1940s, American chemist Willard Libby developed a method for determining when the death of an organism had occurred.

He first noted that the cells of all living things contain atoms taken in from the organism's environment, including carbon; all organic compounds contain carbon.