Now, this is neat: A superheavy element (Z=122, A=292, tentatively named "eka-Thorium" or "unbibium") which is relatively stable (t1/2 ≥ 108 yr) has been observed in nature, in natural Thorium samples. (It's called eka-Thorium because it would sit directly below Thorium on the periodic table; as a result, it's chemically very similar to Thorium, which means it can mix in to Thorium ores and stick there because it doesn't separate very easily)
This is a whole 30 atomic numbers above the next-largest naturally occurring element, Uranium. (Z=92, A=238) It's the first empirical proof that superheavy nuclei can actually exist and be stable.
Edit: Some history - the last time an element was discovered in nature was Francium (Z=87), which was discovered in 1939 by Marguerite Perey. It was thought highly likely that that would be the last time anyone ever did.
Apparently scientists have big doubts about this eka-thorium discovery (http://www.rsc.org/chemistryworld/News/2008/May/02050802.asp). Amnon Marinov, who led the team who claimed to have found the stuff, has said he submitted the article to Nature and Nature Physics, but both turned it down without sending it for peer review.
Sigh. Another lovely idea shot down by unfortunate experimental issues. Their explanation of how they distinguished isotopes from ion combinations seemed a bit too pat; it seemed to rely on being able to predict the interaction energies of nuclei with a great deal of precision. I guess that the experts in that field don't seem too impressed.
Good to see you around here, though! Do you read here often?
Anonymous
June 2 2008, 03:29:38 UTC 7 years ago
Best,
John Baez (http://math.ucr.edu/home/baez/)
June 2 2008, 06:11:31 UTC 7 years ago
Good to see you around here, though! Do you read here often?