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



Ok John

Orbits will go out and wave functions are in.

I will touch upon static electricity phenomenon as observable in metals as
well.

Thanks
Sridhar


On Thu, Dec 18, 2008 at 9:42 PM, John Denker <jsd@av8n.com> wrote:

On 12/18/2008 08:01 AM, sridhar chitta wrote:
I will keep it simple;

Q1
Instead of
"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".

It will read
*
"The tangential velocity keeps the negatively charged electrons in stable
orbits around the positively charged nucleus such that no moderate forces
will make the electrons merge with the nucleus in common elements, even
though they are opposite in charge".

I wouldn't have said that.

First of all, I recommend never talking about "orbits"
in atoms. Orbitals are not orbits. Thinking in terms
of "orbits" was the state of the art for about 3 years,
about 80 years ago. I recommend the term "wavefunction"
because students tend to hear "orbit" even if you say
"orbital" and emphasize that orbitals are not orbits.

Secondly: As several people have stated, s-wave electrons
*do* go inside the nucleus. This is readily observable as
the hyperfine splitting, which is necessarily zero for
wave functions (such as p-waves) that do not appreciably
go inside the nucleus ... but clearly nonzero for the
s-electrons. The s-wave probability is _highest_ at r=0.
See
http://www.av8n.com/physics/orbitals.htm#sec-animation

Thirdly, it is pointless and unphysical to make legalistic
arguments about "common" elements. Electrons do go inside
the nucleus, in every element. They don't usually stay in,
but they do go in. Electron-capture data confirms what we
already know from the hyperfine data. Arguing that electron
capture is "uncommon" doesn't make it any less true or any
less relevant. Electrons do go inside nuclei, and sometimes
they stay.

Fourthly, there are profound limits to our ability to
talk about "velocity" and "orbital" in the same sentence
... because of they are incompatible variables, incompatible
in the Heisenberg sense. You can talk about the spatial
description (x,y,z) *or* you can talk about the orbital
description (N,l,m) and *sometimes* you can switch from
one to the other, but you can't ride both horses at the
same time. For more on this, including a constructive
depiction of what you _can_ say about position within an
orbital, see
http://www.av8n.com/physics/orbitals.htm#sec-animation



*On the other hand, molecular forces like adhesion, which is used in
static
electricity will easily pry away charged fragments from a material* e.g
polymers or plastic combs.

This is getting repetitious. A lot of people (including Ben
Franklin) have asserted that static electricity is confined
to insulating materials ... but it just isn't true.

For details, see
http://www.av8n.com/physics/contact-electrification.htm

Also a widely-used example of static electricity carried
by metal pellets:
http://www.pelletron.com/charging.htm

Information about work functions can be found in textbooks
such as Ashcroft and Mermin, _Solid State Physics_.

This discussion has gone past the point where guessing
and hand-wavy arguments are useful. As some point, you
have to do the physics: real experiments and real
calculations.

If you bang an iron hammer against a copper anvil, you
*will* transfer electrons every time, guaranteed (unless
you take heroic measures to prevent it).
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--
"The battles that count aren't the ones for gold medals. The struggles
within
yourself -- the invisible, inevitable battles inside all of us -- that's
where it's
at : Jesse Owens -famous black American athlete who won 4 gold medals in the
Berlin
Olympics
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Thanks
Sridhar Chitta