Half Life of Radioactive Isotopes

[daveb]

Is there any theory that predicts the halflife of a radioisotope given the number of neutrons and protons in the element? For example, given X protons and Y neutrons, is there anything other than empirical data to predict when half of a given sample will decay? I know there are isalnds of stability, but what (if any) mathematical basis is this based upon?

 

[mgb_phys]

From the size of the nucleas you can predict what type of decay it is likely to undergo and how likely it is to be radio-active.
The more unbalanced it is compared to the stable isotope the higher the activity and so the shorter the half life - but in general I don't think you can directly calculate half life.

The stability islands are based on models of shells in the nucleus but how much this is a fundamental law rather than just a fit to the data I don't know.