# Elements and a sea of stability **URL:** \ **Category:** Factual Questions\ **Created:** [October 26, 2004, 3:35pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238 "2004-10-26T15:35:48Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Capt.Ridley\_s\_Shooting\_Party](https://avatars.discourse-cdn.com/v4/letter/c/cc9497/32.png) [@Capt.Ridley\_s\_Shooting\_Party](https://boards.straightdope.com/u/Capt.Ridley_s_Shooting_Party)\ **Post date:** [October 26, 2004, 3:35pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238/1 "2004-10-26T15:35:48Z")
While waiting for a tutorial, I was reading some of the posters that the department whose building I was in had put up, in this case chemistry. One of them was about the periodic table, and in particular about elements past a certain proton number (I think that’s correct). It stated that once you get past a certain number, around 100, I think, the elements are no longer stable, however it is widely believed that once you get to around 125, there will be a “sea of stability”, although it is unknown whether we will ever be able to reach this. Why is this sea of stability predicted and is it a widely held belief amongst chemists and physicists? Note: the numbers are from memory, so I don’t think that they’re very accurate. ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [October 26, 2004, 4:01pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238/2 "2004-10-26T16:01:38Z")
Technically, it’s **islands** of stability, in a sea of unstable nuclides. In point of fact, two or more protons can only coexist within a nucleus in the presence of neutrons that serve to stabilize them in immediate proximity to each other. For I believe every nuclide but “protium” (H-1) and “tralphium” (He-3) the number of neutrons is at least 100% of the number of protons, and for anything beyond Iron-56, there must be more neutrons than protons for stability to occur. The acceptable percentage range climbs with increasing atomic number, and above Bismuth-209 **no** quantity of neutrons will totally stabilize a nucleus. Nonetheless, relative stability (and relative commonness) occurs in nuclei with 2x[sup]y[/sup] protons and the appropriate number of neutrons for that point on the periodic table. There are complex reasons for this which I don’t fully understand. The “islands of stability” are predicted points on the periodic table above what we presently have discovered or synthesized where these characteristics occur. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [October 26, 2004, 4:20pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238/3 "2004-10-26T16:20:17Z")
> [@Polycarp](#): > > The acceptable percentage range climbs with increasing atomic number, and above Bismuth-209 **no** quantity of neutrons will totally stabilize a nucleus. I’m a little confused; do you mean above the atomic weight of 209 or above the atomic number or Bismuth (83)? Or a third meaning? ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [October 26, 2004, 5:08pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238/4 "2004-10-26T17:08:25Z")
> [@wevets](#): > > I’m a little confused; do you mean above the atomic weight of 209 or above the atomic number or Bismuth (83)? Or a third meaning? Either way, actually. Bismuth-209 is the sole nuclide of the (nuclearly) heaviest stable element, atomic number 83. No. 82, lead, has four stable isotopes, but quite a few of the elements just below them are single-stable-nuclide ones. And elements #84-94 exist in one of three capacities: trace isotopes; the three metastable nuclides Thorium-232, Uranium-238, and Uranium-235; and breakdown products from the decay of those three. ---
**Author:** ![Excalibre](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@Excalibre](https://boards.straightdope.com/u/Excalibre)\ **Post date:** [October 26, 2004, 7:32pm UTC](https://boards.straightdope.com/t/elements-and-a-sea-of-stability/271238/5 "2004-10-26T19:32:56Z")
> [@Polycarp](#): > > Either way, actually. Bismuth-209 is the sole nuclide of the (nuclearly) heaviest stable element, atomic number 83. No. 82, lead, has four stable isotopes, but quite a few of the elements just below them are single-stable-nuclide ones. And elements #84-94 exist in one of three capacities: trace isotopes; the three metastable nuclides Thorium-232, Uranium-238, and Uranium-235; and breakdown products from the decay of those three. There are no stable isotopes of bismuth. [Course, with a half-life of 19,000,000,000,000,000,000 years it ain’t goin’ nowhere soon.](http://education.jlab.org/itselemental/ele083.html)