How is the half-life of a radioactive material useful for radioactive dating?
The half-life of a reaction is the time take for the initial concentration of a sample to fall to half of its original value.
All organisms have a given concentration of carbon-14 in them. When the organism dies, its carbon-14 concentration decreases due to radioactive decay.
The half-life of carbon-14 is 5700 years. So after 5700 years, the amount of carbon-14 decreases to half its value. After another 5700 years, it decreases to a quarter of its value. So we can infer that the organism is basically 11400 years old.
^^ So there is one example of how half-life can be used for radioactive dating. Hope it helps.