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Name: Ryland W.
Status: other
Grade: 9-12
Location: Outside U.S.
Country: USA
Date:  Fall 2011  

Question:
Do all elements (including synthetic ones) have isotopes?

Replies:
Yes. There is no guarantee, however, that any of them will be stable.

Richard E. Barrans Jr., Ph.D., M.Ed. Department of Physics and Astronomy University of Wyoming


Ryland,

All atoms are isotopes. For example, 14C and 12C are two of the many isotopes of C (carbon). An isotope is an atom of the same type (that is, the same number of protons in the nucleus), yet having differing masses (the sum of the protons and neutrons in the nucleus).

Some isotopes are unstable (radioactive) and others are stable. Everything is made of isotopes.

See the table of nuclides produced by Brookhaven National Laboratories at http://www.nndc.bnl.gov/wallet/nwccurrent.html.

Les

--- Leslie Kanat, Ph.D. Professor of Geology


All the natural elements have isotopes. That is why the average atomic mass on the periodic table has decimal digits. For many of the "synthetic" elements, they do not exist long enough to know for sure but there is no reason to believe that they would not also have isotopes.

Ray Tedder


Of the "common" elements, fluorine Fl9 comes close. Its most common isotope is 19F9. However, it also has synthetic isotopes, one with a nominal atomic mass =18. This isotope 18F9 only has a half-life of only 1.830 hours, atomic mass = 18.000938, so it does not stay around very long on a cosmic “clock”. If you want to dig deeper into this topic search the subject: “Table of the Isotopes” found on a number of web sites ­ for example, CRC Handbook of Chemistry and Physics.

Vince Calder


Sorry, Ryland, the sense of that question is actually unclear to me. So let me answer with a bunch of statements.

There are two elements in the midst of the periodic table with no stable isotopes (Technetium and Protactinium, the "synthetic elements"). All the trans-Uranium elements have no stable isotopes, but several unstable ones are usually known because we have synthesized them and they last just long enough to detect before they disappear; There are several elements with only one stable isotope. There are some elements with six or more stable isotopes. Every combination of protons and neutrons near the normal range of the stable elements has a measurable if short lifetime before decaying radioactively, making it an identifiable unstable isotope. You can browse all the combinations for yourself at these web sites:

http://en.wikipedia.org/wiki/Table_of_nuclides_(complete),

I like this one: http://www.nndc.bnl.gov/chart/ .

I guess every imagined combination of protons and neutrons is in some sense an isotope. And every imagined number of protons is an element. So, almost by definition of the words, the answer to your question is yes. Every element has isotopes.

But perhaps your "isotope" is what I call a "stable isotope? Then in that sense the synthetic elements have _no_ isotopes, at least none that are stable. Stable isotopes last forever if not poked by neutrons or other subatomic particles. And "unstable isotope" is synonymous with "radioactive species". You've probably heard that the synthetic elements are radioactive after we make them. If an isotope is stable, then inevitably some star made some of it in the past and we can find it lying around in the ground on Earth, and then we don't need to make it artificially to see some.

It might surprise you that one or two of the common, natural, found-on-earth isotopes of elements that we eat every day are actually very slightly unstable. They have a radioactive half-life a bit longer than the present age of the universe, so once made in a star, they last long enough for you and me to be made of them and live about as well as we do. We think of them as stable isotopes of their respective element; practically they are, but technically they are not. It's just a little weird to realize that. I think it means that the comfortable idea of a stable element is yet another nuanced thing in this life, not just a straightforward obvious thing.

Jim Swenson


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