Nuclear physicists predict an “island of stability” beyond the current end of the periodic table. But there’s another possibility even further out: an exotic “continent of stability.” [1 of 2]
In 1937, scientists successfully isolated an element that no-one had ever observed in nature: technetium. Its discovery filled a gap in the periodic table between molybdenum and ruthenium. It also kicked off a whole new era, the creation and observation of synthetic elements.
(Side note: technetium, it turns out, does exist in nature. Just in extremely small quantities; there’s evidence, for example, that the natural nuclear reactor in Gabon produced some technetium about 1.7 billion years ago.)
The 20th and 21st centuries saw the discovery of two dozen more synthetic elements. Most of these don’t exist in nature because they’re too large and unstable. Within minutes or seconds or milliseconds of their creation, radioactive decay will reduce the new elements to something more prosaic. The heaviest element ever created, oganesson, has a half-life of 700 microseconds – after which time it decays into livermorium.
(Oganesson is the only element named after a person who is still alive today, by the way, but it’s not common. In fact, scientists have only ever successfully synthesized five or six atoms of oganesson. And I don’t mean at one time, I mean in total. Five or six atoms ever.)
It’s a fact of nature that all the heaviest elements we have been able to create are highly unstable. But there is a theoretical point where we expect to find some heavy and yet relatively stable elements: the so-called “island of stability.” At a certain magic number of protons and neutrons, isotopes of synthetic elements may last for whole seconds! Or maybe even longer – hours, days, years?!?
The possibility of such an island has tantalized nuclear physicists since the late 1960s, but we haven’t reached it yet. Oganesson is pretty close to the island, and indeed it seems to be more stable than you would expect given its atomic weight. The search continues, but there may be another point of stability beyond the island. There may be a whole continent.
[Part 2 coming soon.]