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.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.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.
Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.
So, we start out with two isotopes of uranium that are unstable and radioactive.
They release radiation until they eventually become stable isotopes of lead.
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.