Anybody got the SD on the really high atomic weight elements? The ones that exist in those theoretical “islands of stability” out there beyond atomic number 109? I know in the past they were hypothesized, and given names like eka-lead, and eka-platinum, but I haven’t heard anybody talk about them in years. Not your typical cocktail party conversation, I readily admit, but some of us get our jollies out of watching the periodic table grow. What unique properties might they have? What use would they be?
Good question.
Unfortunately, I learned the table when the hot debate was whether there was a fifth element beyond earth, air, fire, water. 
Seriously, THIS site has some answers…
My girlfriend made me throw out my Scientific Americans when we moved, but I remeber there was a feature article about this subject in late 1999 or early 2000, written by the head of a Russian research team. The gist of was that they had managed to create elements out to 114, maybe 116, and yes, 114 was significantly more stable than previous triple-digit elements.
His last comment was something like “Now comes the really hard part: agreeing on what to name it!”
–sublight.
There are entries for several elements above 109, such as 114 (ununquadium) and 118 (ununoctium), at WebElements.
Element 114 is supposed to have a stable isotope with 184 neutrons. Element 114 has been created, but not that particular isotope so we still don’t know how stable that isotope will be. The isotope of 114 that was created in the decay of element 118 was 9 neutrons short, for example, which is a pretty big difference.
Creation of elements 116 and 118.
Ok, yes there are islands of stability. But no one seems to be speculating on his question as to what the properties of these elements would be.
These sites seem helpful.
http://www.avk.org/element-114/
http://www.wiley-vch.de/vch/journals/2002/press/199817press.html
So, it is water soluble at least.
Hmmm…I’m no chemist so I have nothing to back this up, but is it conceivable that while moving up the ladder of atomic numbers, the likelihood of a stable isotope existing diminishes, but never completely disappears? You know, kind of like prime numbers in arithmetic? They become sparser and sparser as you move up the number scale, but as Euclid proved, however big a given prime number is, you can show that there is a big one.
Interesting theory. But according to my “research” (looking at an on-line periodic table), Bismuth-209 is the heaviest element/isotope that is stable. Granted, there are some heavier isotopes with very long half-lives (e.g., U-238 has one of 4.5 billion years). But Bi-209 is the heaviest stable one. Lead is next with Pb-204, Pb-206, Pb-207, and Pb-208 being stable. (Why Pb-205 isn’t I don’t know, but it’s HL is 15 million years.) Of the 31 observed elements heavier than Bismuth, none have stable isotopes. It doesn’t look likely that larger nucleii will be stable.
FYI: Helium, Lithium, Boron, and Neon are the only elements whose known isotopes are all stable. Technetium (atomic number 43) and Promethium (a.n. 61) are the only lighter-that-Bismuth elements with no known stable isotopes.
The problem with that is that “stability” is a relative thing. If I recall correctly, the “stable” isotope of 113 is believed to have a half-life of about 12 seconds. This is remarkable, compared to the milliseconds of the other isotopes and elements up that high, but were it anywhere else on the periodic table, nobody would consider it stable. On the other hand, in the world of elementary particles, something that lasts a few milliseconds would be considered remarkably stable. There’s always “islands of stability”, isotopes that are more stable than their nearest neighbors, but even those islands get less and less stable as the mass increases. Bummer for Star Trek writers.
Great links! Thanks an ununquintium!
I remember back in high school we referred to element 118 as “riton”, pronounced “Right on!” The one below it was craon.
-Ben