Re: Odd nuclear question

["H.B. Knowles" <hbknowls@ix.netcom.com>]

At 16:02 12/02/1999 Thursday-0600, you wrote:
>Hi all, 
>
>Someone asked me if the orbital speed of an electron depended on it's
>distance from the nucleus.  The entirely unsatisfactory answer that I have
>is "I'm not sure".  Does anyone out there happen to know?  Any references
>would be nice as well, I'd like to brush up on this particular part of
>nuclear theory again.  
>
>My thanks as always, 
>
>Scott Kniffin
>
>RSO Unisys Federal Systems, Lanham, MD
>CHO Radiation Effects Facility, GSFC, NASA
>mailto:Scott.D.Kniffin.1@gsfc.nasa.gov
>
>The opinions expressed here are my own. They do not necessarily represent
>the views of Unisys or NASA.  This material has not been reviewed by my
>manager or NASA.  
>**********************************************************************
The question is, accvording to our current understanding, meaningless. The
electron does NOT move in a little orbit like a planet (if it did, it would
basically follow planetary kinematics, because of the inverse-square force law)
but rather, has a probability density per unit volume. (That' the psi-psi-star
ome may recall). This "cloud of probability" has a shape that is basically
determined by the elctron's angular momentun: for s elecrrons, with zero
(orbital) angular momentum it is spherically symmetric; for orbital ang. mom.
equal to 1 (in units of h /2*pi) it is symmetrical aftert one rotation and so
on. The electrons have spin 1/2 each and this locks into the orbital, giving
rise to "fine structure". By using the operator

                j h/2*pi                ( j = sqrt (-1))

on the psi-function, one can get the momentum at a particular location. This is
indeed consistent with the uncrtainty principle>

The Bohr atom was a first step and is indeed still often invoked as a
conceptual model, but this has its pitfalls.
H.B. Knowles, PhD, Physics Consulting
4030 Hillcrest Rd, El Sobrante, CA 94803
Phone\Fax (510)758-5449
hbknowls@ix.netcom.com
<www.hbknowles.com>
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