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Re: radioactivity



Jack Uretsky wrote:

... Elements fly apart - emitting "stuff" - whenever energy
conservation permits them to do so.
A nucleus in an excited state will decay to a lower state by
gamma emmission.
A nucleus will decay to another more stable nucleus of the
same A and charge different by one unit by beta emission.
A nucleus will split into nuclei of two or more different elements
if the split is energetically possible (think of the neutron and proton
as "elements" in this context).

It would be good for me to direct my students thinking towards the law of
conservation of energy. However, stating that nuclei decay because they can
reach lower energy states does not really get me much closer to a complete
explanation.


You are really answering a different question - why are some
nuclei more stable than others. You should clarify the difference to
the students

Please explain more fully if you can. I don't understand why the questions
are different. More stable means less radioactive, doesn't it?

Think of
a chain of students holding hands. The force is short range - two arm
lengths - but there is no limit to the length of a possible chain.

Good point. I had not thought of it this way before.

There is also a neutron "drip line" - possibly
because of the Pauli principle limiting the number of neutrons that
can be near the center. So having the right mix of n and p is crucial.

I'll look further down this path but any further details here would be great.
Why should the number of neutrons be limited? They obviously are but I don't
know why.


--
Cliff Parker

Never express yourself more clearly than you can think. -- Niels Bohr