On Wed, 2009-04-01 at 14:33 -0700, Ethan Merritt wrote: > On Wednesday 01 April 2009 07:21:16 Thomas Womack wrote: > > A perusal of the PDB reveals that the game of Periodic Table bingo still > > has eleven rounds to run: > > > > scandium, titanium, germanium, zirconium, niobium, neodymium, > > dysprosium, thulium, hafnium, bismuth and thorium remain absent from PDB > > entries. > > Does this imply that there is a PDB entry containing Radon?
I defined 'plausible' as a half-life greater than a billion years, though I wouldn't have been totally amazed to see a plutonium or technetium derivative. Elements with half-lives 10^6 to 10^9 years for the most stable isotope are Np, Tc, Cm, Pu; next shortest is 31kyears for 231Pa. The long-lived curium-247 and plutonium-244 isotopes are neutron-heavy and inconvenient to produce. The web-accessible subset of the ICSD features a technetium arsenide, a plutonium boride, a sodium neptunate(VII) and an americium iodide. Tom
