So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.So, you might say that the 'full-life' of a radioactive isotope ends when it has given off all of its radiation and reaches a point of being non-radioactive.
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.
Free 5-day trial 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.
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.