I have six unanswered questions which I believe are fundamental to an understanding of the universe. They all relate to the structure of the hydrogen atom for which the current models are woefully inadequate.
The first of these was formulated most succinctly by Richard Feynman when he asked every physicist to write the value of the Fine Structure Constant on his blackboard and ponder its significance:
1 What is the physical significance of the Fine Structure Constant ?
What Feynman was asking, and I am reiterating, is not how to calculate its value, that is well understood, it is much more fundamental than that. What he is looking for is an explanation as to the fundamental nature of the Fine Structure Constant. What mechanisms or physical processes lie behind its existence and thereby behind its value?
2 Why does the hydrogen atom have energy levels which are quantised?
When Bohr first formulated his model for the hydrogen atom he took the idea from another physicist, John Nicholson, that the angular momentum of the electron orbiting the hydrogen atom could only take on certain discrete values which were integer multiples of Planck’s constant. He never sought to explain why this should be the case and no one since has bothered to ask the question. Subsequent theories all rest on this same assumption. De Broglie, for example, suggested that the electron could be regarded as a wave as well as a particle. He calculated the wavelength as Planck’s constant divided by the linear momentum of the electron. The energy levels all then corresponded to harmonics each of some fundamental frequency and a harmonic is an integer multiple of some fundamental frequency. In effect this is making the same assumption as Bohr, simply restated in terms of a wavelength rather than in terms of angular momentum. Schrödinger developed his wave function, but in doing so he used de Broglie’s formula for calculating the wavelength. So in effect he was making the same basic assumption. No one has since bothered to even ask the question and nowhere is there an explanation of why the orbits of the electron can only take on characteristics which are discrete.
3 The third question is in a similar vein and concerns another of Bohr’s assumptions which remains unanswered by subsequent theories.
According to classical mechanics, the electron orbiting the atomic nucleus is subject to continuous centripetal acceleration and should therefore emit synchrotron radiation. This in turn should cause the orbit of the electron to decay and eventually the electron to fall into the atomic nucleus or spin off into space. It does not, there is no synchrotron radiation from the hydrogen atom, why?
Bohr chose to overlook this rather inconvenient fact and nobody since has thought to provide an explanation as to why the electron does not emit synchrotron radiation.
4 While the Bohr model is no longer considered an accurate description of the hydrogen atom, it does nevertheless describe the essential geometry of the atom. The orbits of the Bohr model correspond to the orbitals of the current model.
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
5 The actual energy of the electron orbiting the nucleus of the Bohr model decreases with increasing energy level. This is obfuscated in the descriptions of the atomic energy levels by talking about energy potential rather than absolute energy level. Nevertheless the energy of a supposedly higher energy state is less than that of a lower energy state.
How can this be and what has happened to the missing energy?
6 Finally and perhaps the most difficult question of all to answer is:
What is the nature of the wave particle duality? What is its physical nature, in other words precisely what is it that is waving?
QUOTE (Norman Graves+Jun 8 2010, 08:13 AM)
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
Thanks for posting this information. I am a layman who tries to grasp electron behavior and your post gives me food for thought. My guess regarding your question is that while the energy level of an individual atom may cause the size of the electron orbit to fluctuate greatly, this energy circulates among atoms within a system and would tend to dissipate as such. I would think that only by raising the average energy level of the system would enough atoms increase in energy level and size for periods that were sustained enough to exhibit observable behaviors at the molar level.
It is my impression that phase change, for example, happens for the vast majority of water molecules at 0C and 100C, but I think there are always some molecules which are getting enough energy to sublimate or otherwise change behavior according to the specific circumstances of that molecule at a particular moment. In other words, I think the standard behavior that is generally observed for substances at particular levels of temperate and pressure are normative but not absolute. Energy dissipates through contact but not in a perfectly uniform way, I think. Someone with more expertise may correct me, but this is my impression.
How does the expanding size of the atom due to energy level affect its behavior?
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
Thanks for posting this information. I am a layman who tries to grasp electron behavior and your post gives me food for thought. My guess regarding your question is that while the energy level of an individual atom may cause the size of the electron orbit to fluctuate greatly, this energy circulates among atoms within a system and would tend to dissipate as such. I would think that only by raising the average energy level of the system would enough atoms increase in energy level and size for periods that were sustained enough to exhibit observable behaviors at the molar level.
It is my impression that phase change, for example, happens for the vast majority of water molecules at 0C and 100C, but I think there are always some molecules which are getting enough energy to sublimate or otherwise change behavior according to the specific circumstances of that molecule at a particular moment. In other words, I think the standard behavior that is generally observed for substances at particular levels of temperate and pressure are normative but not absolute. Energy dissipates through contact but not in a perfectly uniform way, I think. Someone with more expertise may correct me, but this is my impression.
How does the expanding size of the atom due to energy level affect its behavior?
LITT, he is desperately mistaken in his understanding, so don't take it as gospel.
Granouille, what precisely did you not understand about the question ?
QUOTE (Norman Graves+Jun 8 2010, 08:13 AM)
I have six unanswered questions which I believe are fundamental to an understanding of the universe. They all relate to the structure of the hydrogen atom for which the current models are woefully inadequate.
The first of these was formulated most succinctly by Richard Feynman when he asked every physicist to write the value of the Fine Structure Constant on his blackboard and ponder its significance:
1 What is the physical significance of the Fine Structure Constant ?
What Feynman was asking, and I am reiterating, is not how to calculate its value, that is well understood, it is much more fundamental than that. What he is looking for is an explanation as to the fundamental nature of the Fine Structure Constant. What mechanisms or physical processes lie behind its existence and thereby behind its value?
2 Why does the hydrogen atom have energy levels which are quantised?
When Bohr first formulated his model for the hydrogen atom he took the idea from another physicist, John Nicholson, that the angular momentum of the electron orbiting the hydrogen atom could only take on certain discrete values which were integer multiples of Planck’s constant. He never sought to explain why this should be the case and no one since has bothered to ask the question. Subsequent theories all rest on this same assumption. De Broglie, for example, suggested that the electron could be regarded as a wave as well as a particle. He calculated the wavelength as Planck’s constant divided by the linear momentum of the electron. The energy levels all then corresponded to harmonics each of some fundamental frequency and a harmonic is an integer multiple of some fundamental frequency. In effect this is making the same assumption as Bohr, simply restated in terms of a wavelength rather than in terms of angular momentum. Schrödinger developed his wave function, but in doing so he used de Broglie’s formula for calculating the wavelength. So in effect he was making the same basic assumption. No one has since bothered to even ask the question and nowhere is there an explanation of why the orbits of the electron can only take on characteristics which are discrete.
3 The third question is in a similar vein and concerns another of Bohr’s assumptions which remains unanswered by subsequent theories.
According to classical mechanics, the electron orbiting the atomic nucleus is subject to continuous centripetal acceleration and should therefore emit synchrotron radiation. This in turn should cause the orbit of the electron to decay and eventually the electron to fall into the atomic nucleus or spin off into space. It does not, there is no synchrotron radiation from the hydrogen atom, why?
Bohr chose to overlook this rather inconvenient fact and nobody since has thought to provide an explanation as to why the electron does not emit synchrotron radiation.
4 While the Bohr model is no longer considered an accurate description of the hydrogen atom, it does nevertheless describe the essential geometry of the atom. The orbits of the Bohr model correspond to the orbitals of the current model.
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
5 The actual energy of the electron orbiting the nucleus of the Bohr model decreases with increasing energy level. This is obfuscated in the descriptions of the atomic energy levels by talking about energy potential rather than absolute energy level. Nevertheless the energy of a supposedly higher energy state is less than that of a lower energy state.
How can this be and what has happened to the missing energy?
6 Finally and perhaps the most difficult question of all to answer is:
What is the nature of the wave particle duality? What is its physical nature, in other words precisely what is it that is waving?
'Why'' questions concerning natural phenomena are generally useless.
The first of these was formulated most succinctly by Richard Feynman when he asked every physicist to write the value of the Fine Structure Constant on his blackboard and ponder its significance:
1 What is the physical significance of the Fine Structure Constant ?
What Feynman was asking, and I am reiterating, is not how to calculate its value, that is well understood, it is much more fundamental than that. What he is looking for is an explanation as to the fundamental nature of the Fine Structure Constant. What mechanisms or physical processes lie behind its existence and thereby behind its value?
2 Why does the hydrogen atom have energy levels which are quantised?
When Bohr first formulated his model for the hydrogen atom he took the idea from another physicist, John Nicholson, that the angular momentum of the electron orbiting the hydrogen atom could only take on certain discrete values which were integer multiples of Planck’s constant. He never sought to explain why this should be the case and no one since has bothered to ask the question. Subsequent theories all rest on this same assumption. De Broglie, for example, suggested that the electron could be regarded as a wave as well as a particle. He calculated the wavelength as Planck’s constant divided by the linear momentum of the electron. The energy levels all then corresponded to harmonics each of some fundamental frequency and a harmonic is an integer multiple of some fundamental frequency. In effect this is making the same assumption as Bohr, simply restated in terms of a wavelength rather than in terms of angular momentum. Schrödinger developed his wave function, but in doing so he used de Broglie’s formula for calculating the wavelength. So in effect he was making the same basic assumption. No one has since bothered to even ask the question and nowhere is there an explanation of why the orbits of the electron can only take on characteristics which are discrete.
3 The third question is in a similar vein and concerns another of Bohr’s assumptions which remains unanswered by subsequent theories.
According to classical mechanics, the electron orbiting the atomic nucleus is subject to continuous centripetal acceleration and should therefore emit synchrotron radiation. This in turn should cause the orbit of the electron to decay and eventually the electron to fall into the atomic nucleus or spin off into space. It does not, there is no synchrotron radiation from the hydrogen atom, why?
Bohr chose to overlook this rather inconvenient fact and nobody since has thought to provide an explanation as to why the electron does not emit synchrotron radiation.
4 While the Bohr model is no longer considered an accurate description of the hydrogen atom, it does nevertheless describe the essential geometry of the atom. The orbits of the Bohr model correspond to the orbitals of the current model.
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
5 The actual energy of the electron orbiting the nucleus of the Bohr model decreases with increasing energy level. This is obfuscated in the descriptions of the atomic energy levels by talking about energy potential rather than absolute energy level. Nevertheless the energy of a supposedly higher energy state is less than that of a lower energy state.
How can this be and what has happened to the missing energy?
6 Finally and perhaps the most difficult question of all to answer is:
What is the nature of the wave particle duality? What is its physical nature, in other words precisely what is it that is waving?
'Why'' questions concerning natural phenomena are generally useless.
QUOTE (Granouille+Jun 8 2010, 02:20 PM)
LITT, he is desperately mistaken in his understanding, so don't take it as gospel.
Why don't you correct it then?
Why don't you correct it then?
QUOTE (Norman Graves+Jun 8 2010, 08:13 AM)
4 While the Bohr model is no longer considered an accurate description of the hydrogen atom, it does nevertheless describe the essential geometry of the atom. The orbits of the Bohr model correspond to the orbitals of the current model.
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
This information is very incorrect.
1) The Bohr model suggests that Hydrogen is a planar system while physical atomic hydrogen has spherical symmetry. So the Geometry is misleading.
2) The diameters of the orbits in the Bohr model are proportional to n^2, while the energy levels are proportional to n^(-2), so there is no Bohr hydrogen with a diameter of 10 times normal. Also instead of energy being proportional to the square of the diameter as Norman writes, they are inversely proportional. So for n=1, the energy would be -13.6 eV, and for n=10, the energy would be -0.136 eV. And at n=100, the energy is a mere -0.00136 eV. When the energy gets to 0, the electron is no longer bound to the proton and you have ionized the atom of hydrogen. That's why the energy of the n=1 state of hydrogen is called the (negative of) ionization energy, 13.6 eV.
3) Physical and chemical properties of elements in bulk at common temperatures are determined by the electrodynamics of their ground state. This in turn determines the atom's (or molecules) shape and size. Hydrogen's ground state at terrestrial temperatures and pressures is not as atomic hydrogen (as modelled by Bohr) but as a diatomic molecular gas.
4) n=10 atomic hydrogen does not have the same spectroscopic, physical and chemical properties as n=1 atomic hydrogen. It is however still classified as elementally hydrogen, although no discussion of its chemical or physical nature would neglect that it is in an excited state and that state will last but a few nanoseconds at best. In nuclear chemistry, where energies of 1 MeV are more the norm, n=1 hydrogen is negligibly different from n=100 or even fully ionized hydrogen.
Even a tertiary source on the Bohr model gives you all of the above.
See also: http://en.wikipedia.org/wiki/Hydrogen_spectral_series
The size of the orbits in the Bohr model increase as the square of the energy level, so an atom with an energy level of 10 is 100 times the diameter of one in the base energy state, and one with an energy level of 100 is 10,000 times larger. Since the physical and chemical properties of the atom must ultimately be determined by its shape and size:
How is it possible for an atom to retain the same physical and chemical properties while its size varies over such a large dynamic range?
This information is very incorrect.
1) The Bohr model suggests that Hydrogen is a planar system while physical atomic hydrogen has spherical symmetry. So the Geometry is misleading.
2) The diameters of the orbits in the Bohr model are proportional to n^2, while the energy levels are proportional to n^(-2), so there is no Bohr hydrogen with a diameter of 10 times normal. Also instead of energy being proportional to the square of the diameter as Norman writes, they are inversely proportional. So for n=1, the energy would be -13.6 eV, and for n=10, the energy would be -0.136 eV. And at n=100, the energy is a mere -0.00136 eV. When the energy gets to 0, the electron is no longer bound to the proton and you have ionized the atom of hydrogen. That's why the energy of the n=1 state of hydrogen is called the (negative of) ionization energy, 13.6 eV.
3) Physical and chemical properties of elements in bulk at common temperatures are determined by the electrodynamics of their ground state. This in turn determines the atom's (or molecules) shape and size. Hydrogen's ground state at terrestrial temperatures and pressures is not as atomic hydrogen (as modelled by Bohr) but as a diatomic molecular gas.
4) n=10 atomic hydrogen does not have the same spectroscopic, physical and chemical properties as n=1 atomic hydrogen. It is however still classified as elementally hydrogen, although no discussion of its chemical or physical nature would neglect that it is in an excited state and that state will last but a few nanoseconds at best. In nuclear chemistry, where energies of 1 MeV are more the norm, n=1 hydrogen is negligibly different from n=100 or even fully ionized hydrogen.
Even a tertiary source on the Bohr model gives you all of the above.
See also: http://en.wikipedia.org/wiki/Hydrogen_spectral_series
QUOTE (Norman Graves+Jun 8 2010, 08:13 AM)
6. Finally and perhaps the most difficult question of all to answer is:
What is the nature of the wave particle duality? What is its physical nature, in other words precisely what is it that is waving?
What is the nature of the wave particle duality? What is its physical nature, in other words precisely what is it that is waving?
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