What three things must be known to perform radiometric dating?

Answer 1

To perform radiometric dating, one must know:

1. The initial amount of the parent isotope present in the sample (or the ratio of parent isotope to a stable daughter isotope).
2. The half-life of the parent isotope, which is the time it takes for half of the parent isotope to decay into the daughter isotope.
3. The current amount of the parent isotope and/or the amount of the daughter isotope in the sample, which can be measured with a variety of techniques such as mass spectrometry.