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Name: George
Status: educator
Grade: 9-12
Country: Spain
Date: Winter 2012-2013


Question:
Entering "most stable isotope of rutherfordium" in Google search gives different results in terms of which isotope and half-lives- even the same isotope is attributed different half-lives. Is there a "definitive" source for the periodic table or are these discrepancies (at least the minimal ones) due to element/isotope instability and therefore difficulty in obtaining a "precise" result?

Replies:
Hi George,

Isotopes are either stable or radioactive. Radioactive isotopes undergo radioactive decay. Stable isotopes do not undergo radioactive decay (or if they do, the half life is so long that it "does not count".). In this sense, there is no "most stable isotope" of any element. It is either stable or it is not.

Debb Glosser University of Pittsburgh Geology and Planetary Science


Hi George,

Thanks for the question. Measuring the half-life of an isotope of Rutherfordium is quite difficult and there is a lot of uncertainty in the half-live. The reason for this uncertainty is that few atoms of Rutherfordium are produced in an experiment and MANY atoms are needed to obtain a reliable half-life value from the standpoint of a statistical analysis.

For research purposes, the half-lives of isotopes are available in the "Table of Isotopes, 8th Edition." You can look this up on the Internet. It is the standard reference for nuclear physics.

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell


Hi George,

This is an inherent complexity when working with synthetic, tiny quantities of radioactive materials. Instability and measurement of tiny, very fast decays are contributing factors in imprecision. There are differing ways of making Rf, the "cold" or low excitation energy(10-20 MeV) or the "hot" or high excitation energy(40-50 MeV) and the differing decay or isomers each method produces. For these heavy, synthetic materials, decay via alpha, beta, gamma, electron capture and others, coupled with isomerization make for large discrepancies in the measured values of the half-life.

http://ie.lbl.gov/education/isotopes.htm from Lawrence Berkeley National Laboratory and http://www.nndc.bnl.gov/ from Brookhaven National Laboratory are excellent references.

Thank you for an excellent question! Peter E. Hughes, Ph.D. Milford, NH


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