Yes, but this precisely is the field of nuclear physics. It's not relevant to chemical reactions where there is no breaking up of the nucleus. Chemical reactions are at the level of bonds as Si Modo referred to. Chemical bonds do not demonstrate mass defects. It's all about energy there, mass doesn't come into the equation, literally.

The mass defect in nuclear physics is precisely what demonstrates the conversion of matter to energy. It's proof of it. That's why a chemical explosion, such as from TNT, might be impressive when you use tons or kilotons of it, but a nuclear explosion, based on E=mc², is orders of magnitude worse, even with as little as 600 milligrams (yes, less than a gram) in the case of Little Boy over Hiroshima.

But the paradigm used here is 'classical' chemistry and physics. If we were to approach this issue quantum-physically, then we'd be talking about wave functions and energy states in both cases and the difference would not be as clear cut.

No problem with that, quite the contrary.

I apologize. I wasn't trying to demean. It is ALWAYS good to question. And the more you know, the more you have questions. You obviously have a good knowledge of this and an interest in it and I hope that you keep looking into it. I'm not biased in any way, but it is the most facinating area there is .

WoI was fabulous in pointing out that you were crossing nuclear physics with chemical thermo. I didn't see that happening and that explains the point you were making. The difference between the forces between atoms and the energy of keeping atoms together (bonds) is very different from the enrergy that keeps atoms together.

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I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition

My key point - that I keep reading about - is that the energy released from bonds of any type, nuclear or atomic, has it's own mass. ie mass is not converted to energy but rather removed as a component of the energy.

In the case of of nuclear bonds this is well demonstrated experimentally and put to astounding uses.

In the case of atomic bonds there is no demonstrated evidence because of the measurement difficulties inherent due to the relatively small magnitude of atomic bonding forces. Hence in this case the theory remains unsubstantiated. Although experimental verification may also lead to astounding applications, it at the moment remains a curiosity of little practical use.

I think the key points:

"Energy has mass and this mass is transfered with the energy in the breaking of both nuclear and atomic bonds."

VS.

"Mass is converted into energy only in the breaking of nuclear bonds."

Need to be challenged.

Experimentally this is correct, but theoretically it can be otherwise. It was a big enough challenge to get the world to believe the mass-energy conversion in nuclear fission. To do the same with chemical reactions must be more difficult by order of the magnitude of the difference in forces!!!

Careful with that word, "proof". The alternate explanation that I am presenting is that the energy has mass. Further, if it has mass in nuclear bonds, then why not atomic bonds? Are we to accept that energy is the same everywhere or different depending on where you find it?

It seems the "Penning Trap" precedes my musings.

Some refs:

http://dspace.mit.edu/bitstream/1721...1/28596082.pdf
See: "Weighing chemical binding energies"

SpringerLink - Journal Article
contains a tantalising abstract that mentions the mass off electronic binding energies.

Spectrometry provides precision for the masses - CERN Courier

Sorry for being over sensitive.

You weren't; my response was obnoxious .
The fundamental issue related to the points you make is the definition of mass. There is the mass that we commonly use; that is an observer-independent mass (ie. the mass we get when we measure it directly using a balance or indirectly using dynamics). This is an invariant mass. The other mass is a relativistic mass that is applicable in relativistic conditions (ie. with a speed approaching or at the speed of light).

According to relativity, a classic particle with an invariant mass cannot travel at the speed of light. Photons, both waves and particles, can and do travel at the speed of light. They have no invariant mass for the simple reason that they only travel at the speed of light. They do have relativistic mass. (This seems rather circular and can make one dizzy.)

While nuclear fission demonstrates a mass-energy equivalence, all the energy generated in fission is not mass related. Rather it is a combination of the kinetic energy of the particles of the products of fission and the release of photons (which have no invariant mass but do have relativistic mass). This difference between mass of products and reactants is called the mass defect, as WoI mentioned, meaning the mass of the system (the fission reaction) is smaller than the sum of the invariant masses of its parts. The mass defect is equal to the binding energy of the reactants divided by the square of the speed of light (from E=mc^2).
Yes, these references demonstrate that the mass-energy relationship can be significant in measured chemical results when propagated into larger systems.

When computational chemistry is done on compounds containing a heavy atom, such as a lanthanide or an actinide, one has to take into account the relativistic effects on the invariant mass of the electrons in the shells close to the nucleus. These “core” electrons, while not traveling at the speed of light, have a speed approaching the speed of light. The larger nuclei of these heavy elements contribute larger coulombic forces on their core electrons leading to a large angular momentum of the electrons, thus a larger speed of those core electrons. This is, of course, an approximation because we are mixing invariant masses with relativistic masses. However, taking into account these relativistic effects does lead to better computational chemistry results, in the sense that the results correlate well with experimental or observed results.

When the binding energy is so great that there is a significant mass defect (remember that you have to divide that binding energy by the square of the speed of light to get the mass defect), then you can apply relativistic effects. This is why relativistic effects are applied when the particles involved in the system move at a speed approaching or at the speed of light. The binding energies between atoms is small compared to the binding energies between atomic "particles".

Methods of measurement are improving, but it remains to be seen that the measured energy will be practicle to harvest. If we wanted to see significant mass defects of chemical reactions, we would have to have a prohibitively large system to harvest that mass defect energy. That is one of the keys of energy development – the practicality of harvesting the energy of a system.

__________________
I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition

I just found a link for further reading about mass defect and its significance that WoI and I are talking about. It is good to look at different explanations of a topic.

Is the whole the sum of its parts?

__________________
I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition

Yes, I saw that. It presented nothing new to my understanding. In fact it does not categorically discount the relevance of mass-energy equivalence in chemical bonds and only suggest's that it so small we can't measure it.

The Penning trap trap's a single ion and measures it's mass by it's interaction with the magnetic fields in which it is contained. I can see how this can be used to investigate the presence of a mass defect between ions with different numbers of electrons.

I believe the following deals well with the "problems of relativistic mass".
http://www.physicstoday.org/vol-42/i...2no6p31_36.pdf

The cause of the dilemma is well covered in the last two pages. If his comments on the balance of literature is correct then no number of references will help us other than the fact this article was written before the popular rise of the internet.

Indeed. I have not from the start seen any industrial applications.

That's a great paper. Okun is one of the most cited on the subject of relativistic mass.

At work, I could seach papers that cite him (under the assumption that he is still well cited) and see where the current literature stands. I don't have access to those databses from home.

Of couse, that's assuming I actually remember to do that search...I kind of get pretty focused on my work during the week. I will try though, because you have piqued my interest, too.

As long as there is continued research in the area, and continued funding, we can hope that it does get somewhere.

__________________
I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition

Gentlemen, this is all very interesting, but there remains an unaddressed issue.

Stripped to its essence I would say the situation is as follows:
* Nuclear binding energy is a well established fact, that is experimentally confirmed.
* Chemical binding energy is predicted theoretically, is orders of magnitude smaller than nuclear binding energy and close to being the subject of experimental confirmation, though not quite there yet. (At least not in 1993 : The Vasant Natarjan paper).

The issue I have is with 'theoretically predicted'. None of the links or papers mention the theoretical framework from which the prediction originates. I'm pretty sure it's not early days QP. I reread the chapter 'The structure of simple molecules' in Linus Pauling's 'Introduction to Quantum Mechanics' and found nothing that would constitute such. The wave functions for a multi-ion configuration are basically just 'added up' (not as in 1+1=2 but you know that). Any discrepancy between the values of the sum and the sum of the values is fully quantified and explained as electron resonance.

So what is the theoretical framework that predicted this ? My gut tells me it's got to be either QED or string theory. If it's QED, I'll concede but is it's string theory I've yet got a few aces up my sleeve

Who are you calling a gentleman ?

The energy of chemical bonds is denfinitely so small compared to that of nuclear bonds. I think the point that they are trying to make is that, although small, there exists a mass defect in chemical systems. I agree with that point because I have to take it into account when I use computational chemistry on compounds containing heavy atoms.

Harvesting it is another issue. It's not practical a this point.

One does not get the wave function from addition. One gets the basis set, for example a Linear Combination of Atomic Orbitals, to use in computational theory to approximate a multi-ion wave function which will describe the Molecular Orbital.

The fact that the basis sets used for heavy atoms (lanthanides and actinides) have to be corrected for relativistic effects on the mass of the core electrons indicates that these effects, although small, are important when propagated into a larger system such as a molecule. These basis sets for the heavier atoms are called Effective Core Potentials (ECPs) and my experience shows that you have a snowball's chance of getting a computation to converge on a wave function for the Molecular Orbital if these relativistic effects in heavy atoms are ignored. This group in Stuttgart has made several advancements in coming up with working ECPs. Institute for Theoretical Chemistry

But still, harvesting any energy from relativistic effects in chemical sytems remains to be seen.

__________________
I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition

As a chemist it has to work - the physicists get to make it up and bugger the rest. That makes who the gentlemen?

A framework - yes it has to fit somewhere, but right now the paid work has to fit in the framework.

Will watch for developments.

Not me, I'm a lady.

But without those physicists, a lot of chemists couldn't do the work they do and the converse. Without chemists, a lot of biologists couldn't do the work they do and the converse.

We have to accept that the sciences are becoming more interdiciplinary in research, but never forget that expertise in an area is very important. One has to be versed in a lot of different areas to be an effective scientist these days but be wary of becoming a jack of all trades and master of none.

Perhaps they are buggers, but buggers that are necessary to keep science honest .

__________________
I am an American. That's the way most of us put it, just matter of factly. They are plain words, those four: you could write them on your thumbnail, or sweep them clear across this bright autumn sky. But remember too, that they are more than just words. They are a way of life. So whenever you speak them; speak them firmly, speak them proudly, speak them gratefully. I am an American. ...a tradition