reasonable read

https://www.scientificamerican.com/arti ... ent-e-mc2/

In chemical bonds, ionic bonds and covalent bonds the atomic structure is not disrupted to form a molecule. In nuclear reactions unlike chemical reactions the fundamental particles are either torn apart(fission) or assembled(fusion) to release huge amounts of energy in the form of radiations.
The two processes cannot be compared. Nuclear fusiob/fission is related to particle Physics/ nuclear Physics.
Chemical reactions do have physical elements represented in the chemical equation, but the reaction falls under Chemistry(Organic or Inorganic).

blackhash wrote:In chemical bonds, ionic bonds and covalent bonds the atomic structure is not disrupted to form a molecule. In nuclear reactions unlike chemical reactions the fundamental particles are either torn apart(fission) or assembled(fusion) to release huge amounts of energy in the form of radiations.
The two processes cannot be compared. Nuclear fusiob/fission is related to particle Physics/ nuclear Physics.
Chemical reactions do have physical elements represented in the chemical equation, but the reaction falls under Chemistry(Organic or Inorganic).

I'm not sure you're saying this correctly. In chemical reaction, the atomic structure is changed, as in the electrons that are in some way where a lot of the atomic 'structure' resides, get shuffled around in some way-the various ionic-covalent etc ways that atoms bond into molecules. In nuclear reactions, nucleons in the nucleus are shuffled around in some way--fission and fusion like you said, but you could also have, I don't know if this actually happens , an isotope spit out or absorb one or more neutrons, thus not changing atomic number just turning into a different isotope, and you'd have a nuclear reaction that wasn't fission of fusion. I think one of the ways of making heavy hydrogen is like that, normal hydrogen is bombarded by neutrons and a few of the atoms absorb one. The vast differences in the forces involved in shuffling the loosely held electrons vs the tightly held nucleons result in correspondingly vastly different binding energies so the delta E's of the reactions are vastly different.

crank wrote:

blackhash wrote:In chemical bonds, ionic bonds and covalent bonds the atomic structure is not disrupted to form a molecule. In nuclear reactions unlike chemical reactions the fundamental particles are either torn apart(fission) or assembled(fusion) to release huge amounts of energy in the form of radiations.
The two processes cannot be compared. Nuclear fusiob/fission is related to particle Physics/ nuclear Physics.
Chemical reactions do have physical elements represented in the chemical equation, but the reaction falls under Chemistry(Organic or Inorganic).

I'm not sure you're saying this correctly. In chemical reaction, the atomic structure is changed, as in the electrons that are in some way where a lot of the atomic 'structure' resides, get shuffled around in some way-the various ionic-covalent etc ways that atoms bond into molecules. In nuclear reactions, nucleons in the nucleus are shuffled around in some way--fission and fusion like you said, but you could also have, I don't know if this actually happens , an isotope spit out or absorb one or more neutrons, thus not changing atomic number just turning into a different isotope, and you'd have a nuclear reaction that wasn't fission of fusion. I think one of the ways of making heavy hydrogen is like that, normal hydrogen is bombarded by neutrons and a few of the atoms absorb one. The vast differences in the forces involved in shuffling the loosely held electrons vs the tightly held nucleons result in correspondingly vastly different binding energies so the delta E's of the reactions are vastly different.

I mean the atomic composition remains unaltered in a chemical reaction. In a nuclear reaction you are destroying the composition of the atom.

Again, you are saying the electrons are not part of the 'composition' of the atom. I don't think that can be justified. If you want to restrict the idea of the composition of an atom to the nucleus, then OK. You're better off saying the elements involved don't change in chemical reactions. But that would apply to my possible example of making heavy hydrogen, deuterium, which is also an exception with your phrasing.

crank wrote:

blackhash wrote:In chemical bonds, ionic bonds and covalent bonds the atomic structure is not disrupted to form a molecule. In nuclear reactions unlike chemical reactions the fundamental particles are either torn apart(fission) or assembled(fusion) to release huge amounts of energy in the form of radiations.
The two processes cannot be compared. Nuclear fusiob/fission is related to particle Physics/ nuclear Physics.
Chemical reactions do have physical elements represented in the chemical equation, but the reaction falls under Chemistry(Organic or Inorganic).

I'm not sure you're saying this correctly. In chemical reaction, the atomic structure is changed, as in the electrons that are in some way where a lot of the atomic 'structure' resides, get shuffled around in some way-the various ionic-covalent etc ways that atoms bond into molecules. In nuclear reactions, nucleons in the nucleus are shuffled around in some way--fission and fusion like you said, but you could also have,I don't know if this actually happens , an isotope spit out or absorb one or more neutrons, thus not changing atomic number just turning into a different isotope, and you'd have a nuclear reaction that wasn't fission of fusion. ...

It can, indeed, happen. That is how neutrons are sometimes emitted in nuclear decay chains, that may create a neutron-rich nucleus (outside of the line or island of stability), and which is therefore metastable, and rapidly decays, possibly by neutron emission. This is how free neutrons are generated.

'Free neutrons', more socialist BS!

Cool, I thought that was the case, unfortunately I think my brain is melting and my memory leaking badly.

crank wrote:Again, you are saying the electrons are not part of the 'composition' of the atom. I don't think that can be justified. If you want to restrict the idea of the composition of an atom to the nucleus, then OK. You're better off saying the elements involved don't change in chemical reactions. But that would apply to my possible example of making heavy hydrogen, deuterium, which is also an exception with your phrasing.

Of course the electrons are part of the composition of the atom, but what he possibly meant is that, in chemical reactions, only the outer, valence electrons are involved in the process. Chemistry doesn't touch inner electrons.

EDIT: More info here.

Yeah, I know, and he probably does too, it's the phrasing that I think is misleading, so I was trying to clarify.

I've just realised that I made a mistake in post #26, above. I originally wrote "chain reactions" when I should have written "decay chains". They're not the same, but I've corrected it now. A decay chain only involves one initial nucleus, whereas a chain reaction only happens when there are many nuclei available (to react with a slow neutron).

Macdoc wrote:reasonable read

https://www.scientificamerican.com/arti ... ent-e-mc2/

That was a good read, thanks.

Yeah I enjoyed it ...clarity and I learned something

The quickest answer is this: compare the mass-energy equation:

E = mc2

to the Newtonian equation for kinetic energy:

E = ½mv2

Note the similarity.

The actual derivation of E=mc2 is somewhat involved, but the form of the equation tells you that there's a relationship with kinetic energy (c is, after all, a velocity term, at least from a formal standpoint). I'll look up the details of the derivation later, and see if I can provide a digestible version.

I happen to like the explanations given below that I ran across about a dozen years ago. These lectures are part of a whole series but I have hopefully reduced the amount of reading to the minimum (although I have limited knowledge in this area and I have nothing to do with these lectures).

First, the basics, of which I think the most important is time dilation:
http://galileoandeinstein.physics.virginia.edu/lectures/srelwhat.html

Later, it is explained that Einstein "rescues conservation of momentum" (caused by time dilation) which leads to the relativistic mass increase and ultimately to E=mc^2.
http://galileoandeinstein.physics.virginia.edu/lectures/mass_increase.html

The home page is located at the URL below in case anyone is interested in further reading (the links above are in the The Lectures):
http://galileoandeinstein.physics.virginia.edu/

I ran across the following video yesterday. It is a derivation that may be similar to the one that Cali discussed above. I have limited knowledge in this area, but it seems to be fairly comprehensive as it includes rest mass energy, kinetic energy, and momentum (for massless particles).

It helps to know a little calculus in order to follow it completely, I think.

The equation, E=mc^2, is derived from the kinetic energy of a particle at relativistic velocities. That is; velocities approaching or equal to C. (approximately 300,000 K/s) Bye examining his new theory in this way he showed us the maximum speed anything can move in this universe is c, and no particle with mass can attain a velocity of c. I could find the derivation online, But I'm just pleased I remember it was derived?

I like this one:

E = mc2/√(1 − v2/c2)

as we can see immediately that v cannot be greater than c.

Are you wondering why c is squared?

BWE wrote:Are you wondering why c is squared?

I am. I was also trying to understand why C is there in the first place.

That was a long time ago. I'm older now but not any wiser....

I don't know if it helps, but c is derived (from Maxwell's equations) as the square root of something.

I linked to this explanation a few years ago in a couple of threads.

Not very far down, the speed of light (the speed of propagation of the electromagnetic waves that this is talking about) is derived as one over the square root of the product of two constants: the permittivity and the permeability of free space.

So c2 is just one over the product of those two constants.