metalresearcher
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Periosic table : wht doews it list nonexistent elements ?
The latest 20 years a lot of new elements are synthesized ranging from 100 (Fm) to 118 (Uuo) but the quantities are so small (a few atoms) that no
physical and chemical properties can be determined and the 'periodic' nature can only be extrapolated by theory. E.g. element 111 should be very noble
(following Cu, Ag and Au) but is never prepared more than a few atoms.
So why are al these 'virtual' elements listed in the PT ? I think it starts from 97 Bk or 98 Cf and upward as these elements never existed in nature.
Other elements like 85 At and 87 Fr are never prepared in weighable quantities and thus no properties are known, but these do exist in nature in VERY
MINIMAL quantities as a decay product of more stable higher elements such as Th and U.
What are your opinions on listing these elements ?
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ScienceSquirrel
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The periodic table is used by physicists as well as chemists so we will just have to learn to share politely 
A little bit of astatine chemistry is known and it is very similar to iodine as you would expect.
An interesting and almost entirely man made element on a terrestrial basis is technetium. It is made as a byproduct in nuclear reactors and there are
now tons of it in storage. It is moderately radioactive but the chemistry is extensive and well described.
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metalresearcher
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But Tc (and 61Pm) do also exist in very small amounts in some stars and here on Earth it exists as decay product of U and Pu. so these are not
entirely man made.
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ScienceSquirrel
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Quote: Originally posted by metalresearcher  | | But Tc (and 61Pm) do also exist in very small amounts in some stars and here on Earth it exists as decay product of U and Pu. so these are not
entirely man made. |
What I said. Please read my posts before replying to them!
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bquirky
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My ignorant response might be simply. Where else would you list them ?
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blogfast25
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There is (or at least was, last time I looked) some hope to reach an 'island of stability' among the super heavies, where one or two would
show unexpected stability and the promise of making microscopic amounts might be a reality some day... Not sure whether our physical brothers have
delivered on that yet... The day, say UuoO2, will be available on eBay may be a considerable distance away yet. 
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psychokinetic
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Mendeleev made up heaps of elements.
And he was pretty damned right about them.
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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