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Re: [Phys-l] Prising electrons from the atom (fwd)



Correcte version.

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Date: Wed, 17 Dec 2008 10:32:44 -0600 (CST)
From: Jack Uretsky <jlu@hep.anl.gov>
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See my respnse to Sidhar.
The "Pauli excludion force" is not a force at all, in the usual sense. It is a statement that the probability for two electrons to be in identical states at the same time must be zero. For the concept of a "state". you have to look to quantum mechanics. The principle applies not just to electrons but to particles with spin equal to 1/2 of an odd integer. The principle is usually called "the Pauli exclusion principle." In its simplest application, it requires that the two electrons in the lowest energy level of a Helium atom must have opposite spins, so that they are not in the same "state".
Regards,
Jack



On Wed, 17 Dec 2008, Josh Gates wrote:

I've seen something similar in different places, though it was about
electrons staying in their orbitals/spin states/etc.. It was called the
"Pauli Exclusion Force." Anyone know what that is? Is that some sort
of emergent property of a lower-level, more familiar interaction? I
know where all of that comes from, wavefunction-wise, but is there a
force associated with that, or is it just a property of the wf?

jg

sridhar chitta wrote:
I have two questions to the forum:



1) What kind of force keeps the electrons away from the nucleus.



Can this be called a "nuclear" force ? I have been teaching students
that there are four fundamental forces in nature and that all other forces
are derived from these. Yet, I found this force described in



http://www.worsleyschool.net/science/files/touch/touch.html



"The *nuclear forces* between these two types of objects is so strong
that no earthly conditions can cause the electrons to merge with the
nucleus, even though they are opposite in charge".

Which fundamental force should this "nuclear" force be ascribed to ?



2) Why cannot a hammer and chisel that can exert a force of say, 100
Newtons be used to prise an electron away from the nucleus of a copper atom
in a copper bar given that the radius of an atom is of the order of
10-10meters and the electric force of attraction between a proton and
an electron
that are this far apart is a *mere 2.3 x 10**-8 **Newtons** ?* (Electric and
Magnetic Interactions by Sherwood and Chabay)




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--
"Trust me. I have a lot of experience at this."
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just before leading them into the Little Big Horn Valley



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