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[Re: radioactivity]



Leigh posted this privately it was intended for the list.

Leigh Palmer wrote:

It's pretty straightforward. Neutrons are fermions and as such

two neutrons cannot occupy the same quantum mechanical state
in a nucleus. When all of the energetically bound quantum
states in a nucleus are occupied by neutrons, the next neutron

in must go into a higher (and therefor unbound) energy state.
Of course it will come right out, there being no barrier high
enough to hold it in.

The same mechanism operates in building up the electron shells

around the nucleus of an atom. There is a shell model of the
nucleus as well, largely due to Maria Goepert Mayer. That is
the model in which this explanation is most intuitively seen
to operate.

I'll add one more thing. It turns out that in the case of the
hydrogen atom in its ground state, it is possible to add one
more bound electron. The resulting object, the H- ion, is the
species principally responsible for the opacity of the Sun.

Does that help?

Leigh


Yes it does. Not a lot but it helps. What exactly do you mean
by
enegerticly bound quantum states? I do understand that there
are various
energy states within the nucleus as there are various states
with
electrons. What would cause a neutron to be ejected at any time

regardless of the energy state it was found within? It
certainly would
not be electromagnetic force or gravitation or strong force. At
least
not the way I see things at this moment. I teach Chemistry I in
high
school and therefore we discuss Pauli exclusion principle in
terms of
electrons. At least as far as I have been able to understand it
myself
this has been a "because that's the way it is" sort of thing.
Perhaps
that's as far as it goes.

There is an infinite number of bound electron states in a neutral

atom. There is a finite number of bound states in a neutral atom
to which electrons are added. One cannot add an electron to an H-

ion, for example; there's no bound state for it to go into.
Pretty
much the same thing can be said for a neutron-rich nucleus.

Line spectrum emissions give evidence to the quantum nature of
energy
relating to electrons. What is the evidence that lead to an
understanding of the quantum nature of energy relating to
protons and
neutrons?

It's the quantization of *atomic* energy levels really, not
*electron* energy levels. That's really a shorthand. The earlier
question about multiple energies for alpha particles is related
to nuclei in the same way. The highest energy alpha leaves the
daughter nucleus in its ground state. Lower energy alphas leave
the nucleus in an excited state. They are usually followed
quickly
by a monoenergetic gamma representing the rest of the energy as
the nucleus relaxes to its ground state. Other excited nuclear
states are also produced in other processes; they emit
monochromatic
gammas, too.

Leigh

--- Begin Message ---
Leigh Palmer wrote:

It's pretty straightforward. Neutrons are fermions and as such
two neutrons cannot occupy the same quantum mechanical state
in a nucleus. When all of the energetically bound quantum
states in a nucleus are occupied by neutrons, the next neutron
in must go into a higher (and therefor unbound) energy state.
Of course it will come right out, there being no barrier high
enough to hold it in.

The same mechanism operates in building up the electron shells
around the nucleus of an atom. There is a shell model of the
nucleus as well, largely due to Maria Goepert Mayer. That is
the model in which this explanation is most intuitively seen
to operate.

I'll add one more thing. It turns out that in the case of the
hydrogen atom in its ground state, it is possible to add one
more bound electron. The resulting object, the H- ion, is the
species principally responsible for the opacity of the Sun.

Does that help?

Leigh


Yes it does. Not a lot but it helps. What exactly do you mean by
enegerticly bound quantum states? I do understand that there are various
energy states within the nucleus as there are various states with
electrons. What would cause a neutron to be ejected at any time
regardless of the energy state it was found within? It certainly would
not be electromagnetic force or gravitation or strong force. At least
not the way I see things at this moment. I teach Chemistry I in high
school and therefore we discuss Pauli exclusion principle in terms of
electrons. At least as far as I have been able to understand it myself
this has been a "because that's the way it is" sort of thing. Perhaps
that's as far as it goes.

There is an infinite number of bound electron states in a neutral
atom. There is a finite number of bound states in a neutral atom
to which electrons are added. One cannot add an electron to an H-
ion, for example; there's no bound state for it to go into. Pretty
much the same thing can be said for a neutron-rich nucleus.

Line spectrum emissions give evidence to the quantum nature of energy
relating to electrons. What is the evidence that lead to an
understanding of the quantum nature of energy relating to protons and
neutrons?

It's the quantization of *atomic* energy levels really, not
*electron* energy levels. That's really a shorthand. The earlier
question about multiple energies for alpha particles is related
to nuclei in the same way. The highest energy alpha leaves the
daughter nucleus in its ground state. Lower energy alphas leave
the nucleus in an excited state. They are usually followed quickly
by a monoenergetic gamma representing the rest of the energy as
the nucleus relaxes to its ground state. Other excited nuclear
states are also produced in other processes; they emit monochromatic
gammas, too.

Leigh

Cliff, Please do me a favor and post this for me. It will save me
some effort. I had thought it was a private note.



--- End Message ---