Radioactive dating is called
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.
This decay is an example of an exponential decay, shown in the figure below.
Carbon-14 dating can only be used to determine the age of something that was once alive.
The rule is that a sample is safe when its radioactivity has dropped below detection limits. So, if radioactive iodine-131 (which has a half-life of 8 days) is injected into the body to treat thyroid cancer, it’ll be “gone” in 10 half-lives, or 80 days.
This stuff is important to know when using radioactive isotopes as medical tracers, which are taken into the body to allow doctors to trace a pathway or find a blockage, or in cancer treatments.
Plants absorb C-14 during photosynthesis, so C-14 is incorporated into the cellular structure of plants.
Plants are then eaten by animals, making C-14 a part of the cellular structure of all living things.