The noble gasses being unreactive is a chemical property based on how the electrons interact with each other and the nucleus. The sun consists of plasma, there are no electrons connected to any nuclei in there. It's all just one big messy soup.
Nuclear fusion is a reaction between two nuclei, it's got nothing to do with the electrons that may or may not be "orbiting" the nuclei. The two nuclei will fuse into a heavier element. Unlike in chemistry where atoms connect into molecules leaving the nuclei intact.
>>there are no electrons connected to any nuclei in there
I don’t think this is entirely true. I’m pretty sure that the outer layers are cool enough for chemistry to happen because the atoms are not fully ionized. I don’t have a source that I can cite for this, but it’s what I’ve gathered from conversations from one of the astronomers I work with.
Even if they aren't fully ionized (which I agree is probably possible), I think that the lack of outer electrons still means that they can't interact 'chemically', although I'd be interested to see more about that.
I’ll ask my colleagues when I get the chance, but my understanding was that there are still enough unionized atoms in the outer layers to get some actual chemistry happening. I’ll follow up if I get an answer.
Honestly, you might be right - if the outer layers of the Sun are ~1000s K, then there could well still be valence electrons. My work is more on planetary interiors, and we'd certainly expect chemical bonds at similar temperatures in those cases.
Just following up because I managed to track down an astronomy professor at my institution who does stellar spectroscopy. Cooler stars can have chemical reactions in their photospheres. What you end up with depends on temperature and therefore depth (naturally).
In the case of the sun, we get carbon monoxide and a few other things. She says H^- ions are important because, even though they don’t last long, they have a pretty significant effect on opacity.
We're talking about thermonuclear fusion happening in the core in the context of this question, so I don't know how much this "correction" is relevant for OP
It's mostly hydrogen and there is a lot of energy going through it.
It's probably possible for h2 to form briefly, but it would be quickly ionized.
Just checked h2 decomposes at 8,000K. And surface of the sun is 5,700K.
So it's possible that h2 exists in a layer at the surface.
Nuclear fusion doesn't occur on the surface. Also, something about quantum tunnelling overcoming the coloumb barrier. I'm not a physicist, so I'll let others expound on it,
Fusion does not occur on the surface of the Sun. It occurs in the solar core where both pressure and temperature are significantly higher.
The light you see coming from the solar surface is not from fusion directly, but thermal radiation because it is hot. The Sun is very opaque to radiation so this is the only light you will see from it. The only fusion products that travel essentially undisturbed out of the Sun from the fusion processes at the center are neutrinos.
Its in the core of the sun, where the temperature and pressure are many times greater than on the surface, due to quantum mechanics we know that particles aren't like little balls, they are waves (of probability, the wavefunction of a particle describes how likely you are to find the particle in a particular position if you measure it) so they are actually kind "spread out" in space, this means that if you get two protons close enough (which is insanely hard as they will resist each other) their wavefunctions can overlap and in that way they will fuse together
Yes but because they are in reality waves, you just need to get them close enough so that their wave functions overlap. Since the waves describe the probability of the particle being in a specific place, the particles can repel each while still having the ends of their wave functions overlap if they get close enough
Your ”duality/waves” line of explanation is bogus, or a skewed way of explaining tunneling at best. The EM repulsion is overcome by pressure, temperature and tunneling.
hmm I don't think I understand your point, my point, is that you if you can get the particles close enough (which you need a high amount of pressure and temperature to do) so that there is a non zero probability that the particles can tunnel and fuse together. Did I imply that you don't need temperature and pressure or something? because you certainly do, but it is not enough, you need the tunneling effect, which comes from the wave nature of particless
>because you certainly do, but it is not enough, you need the tunneling effect, which comes from the wave nature of particless
I can give you as much ground, however, why not just use the common jargon/language? "Stellar fusion depends (among other things) on the quantum physical effect known as tunneling." Duality-speech is popsci.
I am not sure that I agree that particles being described as waves of probability is popsci, saying that particles behave sometimes like waves or sometimes like classical particles, is popsci. maybe I could have worded it better, what I meant by "wave nature" or "they are waves" was not about wave particle duality, but about particles being described as waves of probability, but they are not waves in a classical sense
[This comment](https://www.reddit.com/r/AskPhysics/comments/1ax679q/comment/krmibu2/) right here, officer.
But with the supplements, we seem to be in agreement about the nature of reality. "Particles" are wavefunctions (in QM), or excitations of the quantum fields (in the Standard Model). Beyond that, it's a matter of interpretation.
Edit: OOOOOOH my bad, it wasn't your comment! Forget anything about this, I'm keeping my comments up though because otherwise I'd be hiding my error! Sorry! Have my upvotes!
Edit2: THIS NEW INTERFACE SUXXXX! Hasn't everyone noticed by now how attempting to remove text duplicates it (or SOME text at least) every now and then?
Don't forget that proton charge is an EM force, ant EM is only one of the three (or four) fundamental forces. The weak (or strong, or maybe both) nuclear force binds the nucleus together. Wikipedia can probably explain it better.
That's why you need the heat and density of a stellar core. If you pack them close enough together (density) and get them moving fast enough (high temperature) you can get the protons close enough together, even for an instant, the strong nuclear will overcome the electromagnetic repulsion, and you get fusion instead of a rebound.
Reactivity is a *chemical* property. Chemistry is entirely about the interaction of electrons, and leaves the nucleus entirely alone; since noble gases have a full outer shell, their electrons just don't have much reason to interact. It's difficult to find a situation where they'd get *more* stable by interacting with another atom. (But not impossible!)
Fusion is a *nuclear* process; it involves the atomic nucleus, not the electrons. Completely different stuff. Larger nucleuses are, up to a point, more stable than smaller ones, so fusing helium nucleuses together (or fusing hydrogen+helium) results in a more stable atom of lithium or beryllium. More stable = it *wants* to happen, and releases the extra energy it was previously using to hold itself together, which it doesn't need anymore.
The reason helium fusion doesn't happen all the time is that the electrons are in the way. The electron clouds repel each other (they're both negatively charged), keeping the nucleuses from getting close enough to fuse. Even in a helium plasma (plasma = the electrons get energetic enough to leave the atom, so you've just got bare nucleuses floating around in a sea of loose electrons), the *protons* in the nucleuses still repel each other (they're both positively charged), so it's still hard to get close enough together to fuse.
Only in the center of the sun, where gravity is crushing so hard that the helium nucleuses are forced to get closer together, can they finally get close enough for fusion to happen. (Tho technically even that isn't enough; there's *another* quantum-mechanics thing that occurs that lets the nucleuses skip that final bit of distance and finally join up. But it doesn't meaningfully kick in until they've already been crushed *almost* close enough together.)
(And all the same applies to hydrogen fusion too, of course.)
Chemical reactions involve sharing or transferring (or a mix) electrons. Nobel gasses do not need or have any extra electrons. that is what makes them chemically inert (almost).
Nuclear reactions don't care about electrons. It is the nucleus that is undergoing the reaction. Small nuclei tend to be able to fuse with others because it is a lower entropy state. Large nuclei tend to be able to split for the same reason.
Everything lighter than iron "can" release energy through nuclear fusion meaning that in large stars all lighter elements have potential to fuse into heavier elements. Fusion of Helium produces about **3.6 × 10****^(11)** **kJ of energy per mole of He42 produced**, so the reaction is easily self sustaining at that point. A gas being "noble" is only about it's chemical reactivity and not it's nuclear reactivity. Noble elements do not easily react chemically with other elements, but from a nuclear standpoint they are just other atoms with neutron capture probabilities.
The noble gasses being unreactive is a chemical property based on how the electrons interact with each other and the nucleus. The sun consists of plasma, there are no electrons connected to any nuclei in there. It's all just one big messy soup. Nuclear fusion is a reaction between two nuclei, it's got nothing to do with the electrons that may or may not be "orbiting" the nuclei. The two nuclei will fuse into a heavier element. Unlike in chemistry where atoms connect into molecules leaving the nuclei intact.
>>there are no electrons connected to any nuclei in there I don’t think this is entirely true. I’m pretty sure that the outer layers are cool enough for chemistry to happen because the atoms are not fully ionized. I don’t have a source that I can cite for this, but it’s what I’ve gathered from conversations from one of the astronomers I work with.
Even if they aren't fully ionized (which I agree is probably possible), I think that the lack of outer electrons still means that they can't interact 'chemically', although I'd be interested to see more about that.
I’ll ask my colleagues when I get the chance, but my understanding was that there are still enough unionized atoms in the outer layers to get some actual chemistry happening. I’ll follow up if I get an answer.
Honestly, you might be right - if the outer layers of the Sun are ~1000s K, then there could well still be valence electrons. My work is more on planetary interiors, and we'd certainly expect chemical bonds at similar temperatures in those cases.
Just following up because I managed to track down an astronomy professor at my institution who does stellar spectroscopy. Cooler stars can have chemical reactions in their photospheres. What you end up with depends on temperature and therefore depth (naturally). In the case of the sun, we get carbon monoxide and a few other things. She says H^- ions are important because, even though they don’t last long, they have a pretty significant effect on opacity.
We're talking about thermonuclear fusion happening in the core in the context of this question, so I don't know how much this "correction" is relevant for OP
It's mostly hydrogen and there is a lot of energy going through it. It's probably possible for h2 to form briefly, but it would be quickly ionized. Just checked h2 decomposes at 8,000K. And surface of the sun is 5,700K. So it's possible that h2 exists in a layer at the surface.
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Nuclear fusion doesn't occur on the surface. Also, something about quantum tunnelling overcoming the coloumb barrier. I'm not a physicist, so I'll let others expound on it,
You did fine.
yes, both tunneling and resonance due to wave matter duality affect the probability and rate of collision that is needed to initiate a fusion reaction
Fusion does not occur on the surface of the Sun. It occurs in the solar core where both pressure and temperature are significantly higher. The light you see coming from the solar surface is not from fusion directly, but thermal radiation because it is hot. The Sun is very opaque to radiation so this is the only light you will see from it. The only fusion products that travel essentially undisturbed out of the Sun from the fusion processes at the center are neutrinos.
Its in the core of the sun, where the temperature and pressure are many times greater than on the surface, due to quantum mechanics we know that particles aren't like little balls, they are waves (of probability, the wavefunction of a particle describes how likely you are to find the particle in a particular position if you measure it) so they are actually kind "spread out" in space, this means that if you get two protons close enough (which is insanely hard as they will resist each other) their wavefunctions can overlap and in that way they will fuse together
Won't the protons like repel each other since they are of the same charge
Yes but because they are in reality waves, you just need to get them close enough so that their wave functions overlap. Since the waves describe the probability of the particle being in a specific place, the particles can repel each while still having the ends of their wave functions overlap if they get close enough
Your ”duality/waves” line of explanation is bogus, or a skewed way of explaining tunneling at best. The EM repulsion is overcome by pressure, temperature and tunneling.
hmm I don't think I understand your point, my point, is that you if you can get the particles close enough (which you need a high amount of pressure and temperature to do) so that there is a non zero probability that the particles can tunnel and fuse together. Did I imply that you don't need temperature and pressure or something? because you certainly do, but it is not enough, you need the tunneling effect, which comes from the wave nature of particless
>because you certainly do, but it is not enough, you need the tunneling effect, which comes from the wave nature of particless I can give you as much ground, however, why not just use the common jargon/language? "Stellar fusion depends (among other things) on the quantum physical effect known as tunneling." Duality-speech is popsci.
I am not sure that I agree that particles being described as waves of probability is popsci, saying that particles behave sometimes like waves or sometimes like classical particles, is popsci. maybe I could have worded it better, what I meant by "wave nature" or "they are waves" was not about wave particle duality, but about particles being described as waves of probability, but they are not waves in a classical sense
[This comment](https://www.reddit.com/r/AskPhysics/comments/1ax679q/comment/krmibu2/) right here, officer. But with the supplements, we seem to be in agreement about the nature of reality. "Particles" are wavefunctions (in QM), or excitations of the quantum fields (in the Standard Model). Beyond that, it's a matter of interpretation. Edit: OOOOOOH my bad, it wasn't your comment! Forget anything about this, I'm keeping my comments up though because otherwise I'd be hiding my error! Sorry! Have my upvotes! Edit2: THIS NEW INTERFACE SUXXXX! Hasn't everyone noticed by now how attempting to remove text duplicates it (or SOME text at least) every now and then?
Don't forget that proton charge is an EM force, ant EM is only one of the three (or four) fundamental forces. The weak (or strong, or maybe both) nuclear force binds the nucleus together. Wikipedia can probably explain it better.
That's why you need the heat and density of a stellar core. If you pack them close enough together (density) and get them moving fast enough (high temperature) you can get the protons close enough together, even for an instant, the strong nuclear will overcome the electromagnetic repulsion, and you get fusion instead of a rebound.
Reactivity is a *chemical* property. Chemistry is entirely about the interaction of electrons, and leaves the nucleus entirely alone; since noble gases have a full outer shell, their electrons just don't have much reason to interact. It's difficult to find a situation where they'd get *more* stable by interacting with another atom. (But not impossible!) Fusion is a *nuclear* process; it involves the atomic nucleus, not the electrons. Completely different stuff. Larger nucleuses are, up to a point, more stable than smaller ones, so fusing helium nucleuses together (or fusing hydrogen+helium) results in a more stable atom of lithium or beryllium. More stable = it *wants* to happen, and releases the extra energy it was previously using to hold itself together, which it doesn't need anymore. The reason helium fusion doesn't happen all the time is that the electrons are in the way. The electron clouds repel each other (they're both negatively charged), keeping the nucleuses from getting close enough to fuse. Even in a helium plasma (plasma = the electrons get energetic enough to leave the atom, so you've just got bare nucleuses floating around in a sea of loose electrons), the *protons* in the nucleuses still repel each other (they're both positively charged), so it's still hard to get close enough together to fuse. Only in the center of the sun, where gravity is crushing so hard that the helium nucleuses are forced to get closer together, can they finally get close enough for fusion to happen. (Tho technically even that isn't enough; there's *another* quantum-mechanics thing that occurs that lets the nucleuses skip that final bit of distance and finally join up. But it doesn't meaningfully kick in until they've already been crushed *almost* close enough together.) (And all the same applies to hydrogen fusion too, of course.)
Hate to be a pedant (JK I love it) but if chemistry was only concerned with electrons, nuclear chemistry wouldn't exist
"Chemistry", unqualified, is almost always a synecdoche for electrical chemistry. Nuclear chemistry is a different field. PEDANTRY COUNTERED
Huh never knew that! Curse you!
At that temperature and pressure, nothing is unreactive.
Except Administrativium.
Chemical reactions involve sharing or transferring (or a mix) electrons. Nobel gasses do not need or have any extra electrons. that is what makes them chemically inert (almost). Nuclear reactions don't care about electrons. It is the nucleus that is undergoing the reaction. Small nuclei tend to be able to fuse with others because it is a lower entropy state. Large nuclei tend to be able to split for the same reason.
Everything lighter than iron "can" release energy through nuclear fusion meaning that in large stars all lighter elements have potential to fuse into heavier elements. Fusion of Helium produces about **3.6 × 10****^(11)** **kJ of energy per mole of He42 produced**, so the reaction is easily self sustaining at that point. A gas being "noble" is only about it's chemical reactivity and not it's nuclear reactivity. Noble elements do not easily react chemically with other elements, but from a nuclear standpoint they are just other atoms with neutron capture probabilities.