why neutrons are needed

Discussion in 'Chemistry' started by kaur_08, Sep 17, 2008.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I did already. Also discussed the obvious fact that in the nucleus it is stabilized and extended this nuclear stabilization concept to suggest that tritium might be one of the stable "simple sub assemblies" with alpha particle assembles that make up the nucleus. As I could still edit my post, I made the "neutrons are unstable" statement orange so you can quickly locate it. I hope you will give more than a scan to my post. It contains a lot of thought (almost three hours in the writing) as it has many facts I needed to dig up.

    I am suggesting and making evident a clear pattern (for possible sub nuclear structures that may answer why there is an upper limit on the number of neutrons that can be added to any element. - That is a superficial mystery as more neutrons should make more strong force with no addition to the Coulomb to hold the nucleus together better.) I have pondered this mystery for years and finally decided to collect some facts and try to see some pattern, which I did. Only break of the pattern is the unstable isotope of carbon 14, which I made red in the list of data and suggested pattern of structure. It should be stable, more so that stable C13.

    Perhaps this instability of C14, like the expansion of water when it freezes, is one of God's few miracles? If water were normal and became denser when freezing, life on Earth would be impossible. If C14 were stable then it could not be used for Carbon dating and it would be much harder to show the Creationists their stupidity about God making the Earth with dinosaurs only 6000 years ago.

    Please take the time to read and understand the point of my post which you obviously just skimmed. You are intelligent and thoughtful. I would appreciate your comments.
    Last edited by a moderator: Sep 23, 2008
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  3. kevinalm Registered Senior Member

    Hi Billy, wanted to let you know that I am reading your earlier post and will reply in a day or two. Sorry I didn't read it closely the first time. I thought I had but clearly I just skimmed it. I do have an interesting thought or two but I want to think about them a bit before posting.
    Last edited: Sep 23, 2008
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  5. kevinalm Registered Senior Member

    I meant to post sooner, but your post was very thought provoking and I wanted to mull over a couple of things before I replied. I sometimes get what I like to call my 'screwy ideas' and I generally keep them to myself and punch them full of holes at leasure,

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    but since we're already at the point of wild speculation I'll describe it a little. But first a bit of recap and expansion on the not so wild parts.

    One thing that sticks out in my mind is that not only can neutrons be stabilized, but they can be destabilized. For a single example out of many, many possible, Magnesium 31, beta decay with a halflife of only 230 ms. And then there is proton decay by positron emision. A stable particle destabilized by some process in the nucleus. Clearly very strange things are going on here.

    Now for some 'wilder' stuf. The above got me thinking about what conditions are like in the nucleus. I recalled a formula relating nuclear radius to mass number. (R = 1.2fm * cuberoot(A)). This formula is supposed to be fairly accurate, especially for larger numbers of nucleons. The upshot is that nuclear volume increases almost as if nucleons are small rigid spheres packing together in contact with each other in the nucleus. Which of course is wrong but I thought as first approximation model ...well... maybe we're looking at a close packing problem.

    I wanted to see if a highly mobile (liquid) or a lattice like (solid) model was more appropriate so I tried to make an estimate comparing the kinetic energy per nucleon to the binding energy per nucleon using two different methods, a Heisenburg uncertainty 'guestimate' and a deBroglie wavelenth calculation.

    Which is where the math all blew up in my face.

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    For the nucleon to be localized at anywhere near a 1.2 fm mesh requires a horrific velocity. I didn't try to come up with a firm velocity because I didn't have the time, but were talking in the ballpark of .5c+. Only nucleons don't vary in mass from isotope to isotope that much, especially compared to a single free neutron or proton mass. And if the kinetic energy were that high then the nucleons wouldn't be bound anyway. So now I'm thoroughly confused.

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    In fact, the numbers are so bad I can't figure out how a nucleon can fit in a nucleus, let alone a small portion of it. Of course it is _very_ possible I messed up the calculation, but both methods said basically the same thing, so I don't think that's it.

    I may fiddle around a bit more on the lattice idea, but mostly just for fun. I don't know if you will find any of it interesting or helpfull, but have some fun with it.

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    Last edited: Sep 29, 2008
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  7. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    To Kevinalm:

    Your close to on repeating the "liquid drop" model, whch is old but has had considerable success. Part of my model is it too, only thing I am adding is idea that there are sub clusters of alpha particles and for the smaller A elements only one or two simple sub particle "orbitors" (N, P, 2N, D or occasionally, stablized T).*

    I have not thought about it, but decay by positon emission is interesting to see if there are some common characteristics of when that occurs. It can be as you suggest, a "destablizaion"of an otherwise stable when isolated (even as hydrogen atom nucleus!) proton. I.e. in additon to the stablization of the neutron "orbiting" the alpha mass of my model, the POV that "destabilzation" is possible is a POV worth more consideration, I think. Do you plan to collect list of nuclei that do decay by positron emission? It would be ointeresting to see if they fit in my model as X alphas + P. ---> X alphas + N + (e+) as if some way the chrage ot the orbiting P can be "blasted out" (with about 1/2000 of the mass of the P.) as a positron. If not most of the positron decay isotopes are in my model of the form X alphas + P then my ideas are weaken (and conversely if they are, my ideas grow stronger.)

    I happen to have a copy of revised edition of Nuclear Physics by Enrico Fermi (lecture notes made and revised by his students in 1951.) An appendex of it is a fold out chart of the isotopes, called a Segré Chart. Perhaps you can find a more modern one. It has the number of N & Ps of course, plus life times, modes of decay, relative abundance (on Earth I think) etc. - a hugh amount of information, compactly presented. All my data came from it.
    *Also at least half seriously I am suggesting that radioacive decay often is associated with the rare sort of "head on" collsion of the of the outer "orbitors," but have not looked to see if the nearly stable isotopes do frequently only fit in my model with two "orbitors." I have long wondered what is the nature of the "probability clock" that sets the decay rate / half lifes? It would be interesting to estimate the "surface area" of the "core alpha cluster" and see if when it is relative large compared to the number of orbiters the half lifes are longer. (Lower frequency of "head on"collisons) There would be more than two orbiters only at higher A than I explored in my model and posted their nuclear forms in terms of this model.

    In the case of only a pair of neutral orbitors, I would predict shorter life times than when there is both an N and P orbiter based on the crude idea that with coulumb repulsion, the P is orbiting higher and often passes "over" the N, even if their "projections on the alpha cluster surface" cross. Of course these ideas are sort of silly, but so is the whole liquid drop model. At least they are testable, if one is willing to do more work with the Segré charts etc. Initial I would explore the "almost stable" isotobes, not in the sencse of long life times, but as being next to a stable isotope in the Segré chart especially if next to the heaviest stable ones which I explored in my original post plus larger A "heaviest ones."

    Why there is a lightest stable isotope for every A is obvious - Coulumb force blows them apart if there are too few neutrons to add strong force without charges, but why nature cannot keep adding more neurtons is the puzzle I am trying to model here. My basics idea for an answer in my "alpha cluser core" model is that collisons between the added orbiting Ns become too frequent.
    Last edited by a moderator: Sep 30, 2008

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