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With radiocarbon dating, the amount of the radioactive isotope carbon-14 is measured.
Compared to some of the other radioactive isotopes we have discussed, carbon-14's half-life of 5,730 years is considerably shorter, as it decays into nitrogen-14.
These two uranium isotopes decay at different rates. The half-life of the uranium-238 to lead-206 is 4.47 billion years.
The uranium-235 to lead-207 decay series is marked by a half-life of 704 million years.
Because plants use carbon dioxide for photosynthesis, this isotope ends up inside the plant, and because animals eat plants, they get some as well.
When a plant or an animal dies, it stops taking in carbon-14.
So, we start out with two isotopes of uranium that are unstable and radioactive.
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.
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.
With rubidium-strontium dating, we see that rubidium-87 decays into strontium-87 with a half-life of 50 billion years.
By anyone's standards, 50 billion years is a long time.