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Re: Peroidic Table (was exclusion principle which was electrons)



Uranium atoms are football shaped, not round.
I remember from the liquid drop model that Uranium and Plutonium and other
transuranics are football shaped and that when they absorb a neutron they
fission when the ends bulge out and form asymetrical smaller drops.

Diameter might not be good parameter.

At 11:33 AM 11/15/2003, you wrote:
It is always wise to examine the the truth of the facts that you
wish to explain. How does the diameter of a Uranium atom compare with the
diameter of a hydorgen atom.
Hint: to a good approximation, the density of most elements is
proportional to the atomic weight of the element.




On Sat, 15 Nov 2003, Craig Lucanus wrote:

> Josh Green wrote:
> > shells are something we can "see" from atomic diameters. This would
> > eliminate the possibility of all the electrons filling in the first
shell,
> > since we know that the third electron fills in another shell. This comes
> > not by theory, but by observation, which is explained by shells of
> different
> > levels.
>
> Why can't the observation of atomic diameters be explained by electrons
> spherically milling about the nucleus building outwards with increasing
> population (up to 92 for the naturally occuring elements)? If, by
> observation, you really mean evidence for shells, like the changes noted in
> successive ionization energies of an element, fine. But diameters? Also, I
> disagree that we can 'see' shells or orbitals as these are mathematical QM
> constructs.
>
> If electrons don't simply mill around the nucleus, but do form up in
shells,
> then what set of shell rules do they obey? We have devised a set of
> mathematical rules that seems to fit the observations of chemical
> properties, with a basis in numerology, if that's what you want to call
> quantum numbers, and a knowledge of the number of electrons in an atom. The
> exclusion principle is one of the fundamental mathematical rules.
>
> Applying these rules requires a bit of jiggery- pokery too, like
starting to
> fill outer shells before inner ones are full, without any numerological
> (mathematical) basis for doing so, only knowing that it is a necessary
> proposal if the mathematical rules are to fit the observed properties of
> elements. Nobody has determined, ab initio at least, why this should occur,
> be it from a consideration of atomic number only, or using any of the
> quantum numbers associated with atomic theory.
>
> Nuclear charge (hence Z) only partly determines the potential energy of an
> electron in a multi-electron atom (albeit that it determines the number of
> electrons in the case of a neutral atom, and thus is of arithmetical
> consequence only). Perhaps if we had a full mathematical understanding of
> such atoms instead of the approximation based on the H-atom we are
currently
> stuck with, and if the exclusion principle was then found to be a direct
> consequence of atomic number, then Josh would have an argument. Somehow, I
> think the basic premise that no two electrons can occupy exact same energy
> states would be a part of any new theory, and would simply have to be
> accepted as it is now, with no real understanding of why it has to be.
>
> Perhaps the last sentence touches more on the original question posed by
> Josh about electrons.
>

--
"Don't push the river, it flows by itself"
Frederick Perls