Currently, about 118 elements are discovered but the last 20 can exist only a few milliseconds or even shorter and no phycical and chemical properties
are known. From many of them (105 or higher only a few atoms are made.
So I don't consider these elements as 'real' but more as a curiosity in the sense of 'Hey I found an atom of element 118'. But as a real scientific
value these curiosities these 'elements' are useless as long as no weighable amounts are prepared.
Even 85 Astatine and 87 Francium have no known properties but these elements do exist in nature as the U and Pu decay series.The amounts are however
no more than 35 grams in the entire terrestial crust. watson.fawkes - 15-4-2011 at 13:29
So I don't consider these elements as 'real' but more as a curiosity in the sense of 'Hey I found an atom of element 118'.
Physics doesn't care how long humans live, nor about the atomic abundance in the earth's crust. If californium isn't real, then you
might as well consider bismuth unreal, as it was recently determined to have no stable isotopes. From a purely physical point of view, all forms of
instability are equivalently unstable; the difference in duration is a matter merely of clock calibration.ScienceSquirrel - 15-4-2011 at 14:08
You left out Technetium Z=43 and Promethium Z=61.
Both of them only exist in trace amounts in the entire universe and on earth.
But Technetium has been made in kilogram quantities and it's chemistry is very well described, promethium is more obscure.
There are plenty of compounds that have only a tiny life time as they fly through the detectors of a spectrometer or they hang about in deep space and
there are the things that exist only as calculations by chemical physicists.metalresearcher - 15-4-2011 at 23:29
I don't consider Cf or all radioactive elements as unreal but only those which are made in 'few atom quantities' or half-lives of milliseconds or less
for the most stable isotopes. So I 'acknowledge' Tc, Pm, At, Fr, elements 90-99, as these either do exist in nature even in the smallest quantities
and/or can be synthesized in weighable amounts.Mixell - 16-4-2011 at 01:41
Well, I think that most (if not all) of the unstable elements exist in nature. There are super-massive stars, that weigh more than 20 times than our
sun. Where heavy elements are created (in their core or at the moment of their collapse). In that environment, atomic nucleus's travel at an insane
speed and collapse into each other, creating new elements. So its logical to assume that in those stars, exist at any given time kilograms or maybe
even tonnes of those radioactive elements (probably up to 118 and beyond). blogfast25 - 16-4-2011 at 03:45
Interesting little tidbit on protactinium: acc. John Emsley, author of ‘Nature’s Building Blocks’:
‘In 1961, the UK Atomic Energy Authority extracted 125 grams of 99.9% pure protactinium [Pa] from 60 tonnes of spent uranium fuel elements, this is
still the major world stock of this element.’
According to the same author, lutetium [Lu] is the most expensive metal in the world at $75,000 per kilogram (Pt is $12,800/kg, Au $12,500/kg). gsd - 16-4-2011 at 09:10
According to the same author, lutetium [Lu] is the most expensive metal in the world at $75,000 per kilogram (Pt is $12,800/kg, Au $12,500/kg).
Looks like very old data.
Historically Rhodium is the most expensive of the 8 so called precious metals ( Gold, Silver and 6 PGMs Platinum, Palladium, Rhodium, Iridium, Osmium
and Ruthenium)
If you take a long-term view, prices of Au and Ag go only upward whereas prices of Pt and Pd fluctuate wildly. I distinctly remember for one short
period palladium was more expensive than platinum.
In my school days there was a standard question in school quiz - which is the most expensive metal - And the answer was "Californium 252" then costing
about $10 million per kg.
gsd
PS - I just came across this webpage which says price of Cf is $27 million per gram
gsd
[Edited on 16-4-2011 by gsd]Fleaker - 17-4-2011 at 07:54
Rhenium was around $10,000/gram back around the time of its discovery.
Most rare radioisotopes and elements are very, very expensive. Ozone - 17-4-2011 at 09:42
They are no less elements than 12C, 13C or 1H, 2H. 252Cf, for example, is made is gram-quantities for (at least in one of my labs) use as neutron
source (via SF). The ultimate goal, SFAIK, is to keep making larger nuclei until we reach the next "island of stability". The "Quest for the
Superheavies" will never stop, and will be greately encouraged if 1, the island is reached and. 2, if the atoms formed are as "unusually stable" as
predicted. I suppose that would make them "real"
Cheers,
O3
and, Watson, "Physics doesn't care how long humans live, nor about the atomic abundance in the earth's crust." is great
