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The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.
The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.
It might take a millisecond, or it might take a century. But if you have a large enough sample, a pattern begins to emerge.
It takes a certain amount of time for half the atoms in a sample to decay.
Try It risk-free Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes.
Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson. As we age, our hair turns gray, our skin wrinkles and our gait slows.
But when the organism dies, the amount of C-14 begins to decrease.Carbon-14 (C-14), a radioactive isotope of carbon, is produced in the upper atmosphere by cosmic radiation.The primary carbon-containing compound in the atmosphere is carbon dioxide, and a very small amount of carbon dioxide contains C-14.For example, uranium-lead dating can be used to find the age of a uranium-containing mineral.It works because we know the fixed radioactive decay rates of uranium-238, which decays to lead-206, and for uranium-235, which decays to lead-207.