What is the physical half life of a radioisotope?
The physical half-life of a radioisotope is the average amount of time it takes for half of the original radioactive compound to have undergone radioactive decay. After 5 half-lives, approximately 97% of the original radioactivity of the compound will have decayed. Note that it is not possible to predict when exactly an individual radioisotope atom in the compound will decay.
