Re: [Phys-l] "filling" the space in an atom

["Todd Pedlar" <pedlto01@luther.edu>]

On Thu, 26 Oct 2006 07:35:05 -0500, Brian Whatcott <betwys1@sbcglobal.net>  
wrote:

> At 06:48 AM 10/26/2006, Todd Pedlar wrote:
>
> > > Though I admit to a certain difficulty with the interior space
> > >   of atoms, where perhaps particle ballistics shed metaphorical light,
> > > the space between atoms has been well visualized  instrumentally
> > >   has it not?
> >
> > I presume what you're referring to is the atomic force microscope or
> > electron microscope images that show individual atoms on surfaces...
> > or perhaps x-ray diffraction images that show the presence of scattering
> > centers.
> >
> > In the first case, you're seeing the
> > ___________________________________________________
> > Todd K. Pedlar
>
>
> I noted your velocity, Todd, but the moment of your note was unclear.

Whoops!

I intended to continue.

In the first case, you're seeing the effective "edge" of
the atomic shells (though truly you are only seeing an
effective edge - the probability for observing the electron
at any particular finite radius from the nucleus is finite).  In
such images, you're not really seeing "empty space" - just
the 90% or 95% containment radii for each atom.   The
space between the bumps on the image is really no more
"empty" than the space inside the bumps.

In the second case, you're seeing scattering from the atomic
lattice structure...   Rutherford saw scattering from the
nuclei of his gold atoms in the foil, but we can't draw from
that result that, other than the nuclei, there is empty space
in the gold foil.  The scattering patterns he saw, and the
scattering patterns that one sees in x-ray diffraction,
do not indicate "empty space" alternating with "filled space".
The "gaps" specify angles at which scattering is highly
unlikely due to the probability distributions of interaction
between the x-rays and the material one is scattering them
off of.  While they show areas of high and low probability,
they don't really show "space".

More later, got to get to Quantum Mechanics :)

Todd

___________________________________________________
Todd K. Pedlar
Assistant Professor of Physics, Luther College
pedlto01@luther.edu
___________________________________________________
"A fanatic is one who can't change his mind and
won't change the subject." -- Winston Churchill