# FW: FWIW - RE: [SI-LIST] : Atomic animation

Johnson, David ([email protected])
Tue, 23 Feb 1999 16:02:25 -0800

Just FWIW, to clarify (I hope) the question of whether an orbiting electron
is a particle or an energy wave, what happens if we shoot a neutron through
an atom such that it misses the nucleus? Can the neutron ever "collide"
with orbiting electron particles, or does the neutron just pass straight
through the electron "shells" more or less undisturbed (neglecting gravity)?
Can a "flying" neutron knock an orbiting electron to another orbit or out of
an atom altogether? (My particle physics is a bit rusty and was never very
good in the first place, not to mention never having had any courses in
quantum mechanics.)

---- Dave W. Johnson

-----Original Message-----
From: Douglas McKean [mailto:[email protected]]
Sent: Tuesday, February 23, 1999 3:16 PM
To: [email protected]
Subject: FWIW - RE: [SI-LIST] : Atomic animation

> As an aside, I had forgotten how much "empty space" there actually is in
> an
> atom until I recently read the following analogy (which may not be correct
> at all). The allegation was that if a typical atom (defined by the size of
> the electron rings) were the size of the earth, the nucleus would be the
> size of a football field! Is that even close to the truth?

FWIW Department,

I think those analogies are based on the Bohr atom model -
perfectly round nucleus, perfectly spherical electron orbits, ...
Nuclei diameters are on order of about 10^-4 pm. The radius
of a Cu atom is about 1.29 pm. So there's a factor of roughly
10,000 or there abouts. So here's some 1:10,000 analogies ...

If the nucleas was a The electron would be
-------------------- ---------------------
Golf Ball (about 1.6" D) About 1/4 of a mile away

Softball (about 4" D) About 3/4 of a mile away
Actually a little less.

Basketball (about 10" D) About 1.5 miles away and with this
analogy the electron would be about
the size of a marble.

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