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Have we found a stable super heavy element or created one in a lab, or are they still hypothetical?

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    $\begingroup$ More sci-fi then hypothetical. There's no reason to think any superheavy nuclide wouldn't be highly radioactive (half-life measured in minutes, at most). $\endgroup$ – Mithoron Oct 14 '17 at 0:21
  • $\begingroup$ It depends on how you define "stable." The notion is that there is a region of super heavy isotopes that would have a longer half-life than isotopes which are lighter or heavier. But the "stable superheavies" won't be as stable as say helium-4. $\endgroup$ – MaxW Oct 14 '17 at 0:29
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There already is an element, heavier (higher atomic and mass numbers) than all naturally occurring ones, that is stable enough for everyday use. You are probably using it, well, everyday, in your smoke detector.

It's americium, element 95, with three isotopes having 100+ year half-lives. Americium-241 has a half-life of over 400 years, for americium-243 it's over 7000 years and there is even an odd-odd isomer, with mass number 242, having a half-life over 100 years. (https://en.wikipedia.org/wiki/Americium).

This is not perfect (and whether it's called "superheavy" depends on definition), but the americium is out-lasting other components of smoke detectors, or industrial gauges where americium is also used. In that sense we can indeed call the most long-lasting americium isotopes stable.

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    $\begingroup$ This is just wrong. For some background on stable super heavy elements see scientificamerican.com/article/… $\endgroup$ – MaxW Oct 14 '17 at 3:24
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    $\begingroup$ I thought superheavies have $Z \geqslant 104$, so actinides are supposed to be out of scope. $\endgroup$ – andselisk Oct 14 '17 at 6:19
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    $\begingroup$ So, will we hit the jackpot again like with americium? No one knows. $\endgroup$ – Oscar Lanzi Oct 14 '17 at 13:04
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    $\begingroup$ Am isn't "hitting jackpot", it's just after plutonium, which has most stable isotope with half-life over 80 mln years... $\endgroup$ – Mithoron Oct 14 '17 at 21:41

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