I know there are tables of decay chain of radioactive elements. Is there a way to predict the whole chain from the first radioactive element?


Use the Evaluated Nuclear Structure Data File; search "by decay" and put the nuclide you'd like to start with in "parent." This will also tell you half-lives and Q-values.

A few nuclides have multiple decay modes; for instance radon-221 usually beta-decays to francium-221, but alpha-decays to polonium-217 about 22% of the time. You may find other "forks in the road" depending on where you start.

You ask in a comment about U-235. You can go a little simpler by looking at the chart of nuclides, which lists decay modes:

  • U-235: α
  • Th-231: β
  • Pa-231: α
  • Ac-227: β 99% (neglect α 1%)
  • Th-227: α
  • Ra-223: α
  • Ra-219: α
  • Po-215: α
  • Pb-211: β
  • Bi-211: α 99.3% (neglect β 0.7%)
  • Tl-207: β

That takes you to lead-207, which is stable (and makes up 22% of natural lead).

  • $\begingroup$ hey thanks for the reply I understand there are table we can look up with the decay chains, but have we been able to model and predict sequence? $\endgroup$ – TongMasterFlex Nov 9 '15 at 15:56
  • $\begingroup$ Modern nuclear models are able to predict the energy levels for different nuclides, and that tells you which decays are energetically allowed. In general nuclei with "too many" neutrons will $\beta^-$-decay, nuclei with "too few" neutrons will $\beta^+$-decay, and nuclei that are "too heavy" will $\alpha$-decay. However the details are nontrivial, especially in the no-mans-land of unstable nuclei between lead and thorium. $\endgroup$ – rob Nov 10 '15 at 4:31
  • $\begingroup$ thanks for the reply, but are we able to predict the chain of decay say starting from the U-253 to Fe? $\endgroup$ – TongMasterFlex Nov 23 '15 at 20:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.