vitality00 Posted October 27, 2014 Share Posted October 27, 2014 Can this happen and if so how? How would you accelerate an electron around a nucleus and what would happen to it Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 27, 2014 Share Posted October 27, 2014 (edited) Can this happen and if so how? How would you accelerate an electron around a nucleus and what would happen to it I'm still old fashioned enough to think of electrons orbiting nucleus' (yet the more modern approach is to think of the electron as a type of probability cloud. ) So when I think of it, I liken electrons to the planets where the ones closer in to the sun travel at the fastest rates. So each time an electron absorbs a photon and jumps up to a higher orbital it actually gains energy but it slows down. The reverse happens when the electron emits a photon. It drops down orbitals and speeds up. Now my thoughts maybe out with the ark, but I will start the ball rolling. [A person I used to work with was at university in Copenhagen with Niels Bohr, the person who starting thinking along these lines.] http://en.wikipedia.org/wiki/Bohr_model Edited October 27, 2014 by Robittybob1 Link to comment Share on other sites More sharing options...
Fuzzwood Posted October 27, 2014 Share Posted October 27, 2014 (edited) Think what you like, the model where electrons actually orbit around a nucleus is simply wrong. Quantum, incidentally, simply means quantized (see what I did there?) packets of energy that affect stuff. For example: only a photon of a certain wavelength can create a polaron in a certain area in a photoactive material. It's like an organ pipe which resonates at certain frequencies and only at those frequencies. Edited October 27, 2014 by Fuzzwood Link to comment Share on other sites More sharing options...
Strange Posted October 27, 2014 Share Posted October 27, 2014 (edited) Can this happen and if so how? How would you accelerate an electron around a nucleus and what would happen to it Electrons do not behave like little balls orbiting the centre, so the question doesn't have an answer (the question doesn't really have meaning). Edited October 27, 2014 by Strange Link to comment Share on other sites More sharing options...
elfmotat Posted October 27, 2014 Share Posted October 27, 2014 "What is the velocity of an electron(?)" is not a well-defined question in QM in the first place. Electrons do not have definite momenta. Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 27, 2014 Share Posted October 27, 2014 Think what you like, the model where electrons actually orbit around a nucleus is simply wrong. Quantum, incidentally, simply means quantized (see what I did there?) packets of energy that affect stuff. For example: only a photon of a certain wavelength can create a polaron in a certain area in a photoactive material. It's like an organ pipe which resonates at certain frequencies and only at those frequencies. I'd never seen that word before "Polaron" OK I'll look it up tomorrow. Nite all. Link to comment Share on other sites More sharing options...
Nicholas Kang Posted October 27, 2014 Share Posted October 27, 2014 Fuzzwood, thanks for introducing me a new type of quasiparticle, polaron. Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 28, 2014 Share Posted October 28, 2014 Electrons do not behave like little balls orbiting the centre, so the question doesn't have an answer (the question doesn't really have meaning). How does the quantum Theory explain absorption of photons? Link to comment Share on other sites More sharing options...
Fuzzwood Posted October 28, 2014 Share Posted October 28, 2014 http://en.wikipedia.org/wiki/Excited_state Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 28, 2014 Share Posted October 28, 2014 http://en.wikipedia.org/wiki/Excited_state After absorbing energy, an electron may jump from the ground state to a higher energy excited state.... If the photon has too much energy, the electron will cease to be bound to the atom, and the atom will become ionised. This free electron is virtually stationary isn't it? http://en.wikipedia.org/wiki/Electron_rest_mass The electron rest mass (symbol: me) is the mass of a stationary electron. It is one of the fundamental constants of physics, Link to comment Share on other sites More sharing options...
Strange Posted October 28, 2014 Share Posted October 28, 2014 This free electron is virtually stationary isn't it? Almost certainly not. If the photon had exactly enough energy to free the electron, but give it zero kinetic energy, then the electron would immediately bind to the atom again. A free electron will have some kinetic energy and therefore velocity. Link to comment Share on other sites More sharing options...
swansont Posted October 28, 2014 Share Posted October 28, 2014 Almost certainly not. If the photon had exactly enough energy to free the electron, but give it zero kinetic energy, then the electron would immediately bind to the atom again. A free electron will have some kinetic energy and therefore velocity. By definition, in that case the ionized electron has zero KE when it is infinitely far from the atom. Since it will never actually be in that condition, it will have some KE. 1 Link to comment Share on other sites More sharing options...
Strange Posted October 28, 2014 Share Posted October 28, 2014 By definition, in that case the ionized electron has zero KE when it is infinitely far from the atom. Since it will never actually be in that condition, it will have some KE. Ah, good point. I had forgotten the "to infinity" bit of the definition. Thanks for the reminder! Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 28, 2014 Share Posted October 28, 2014 Almost certainly not. If the photon had exactly enough energy to free the electron, but give it zero kinetic energy, then the electron would immediately bind to the atom again. A free electron will have some kinetic energy and therefore velocity. "Virtually" I might have been more correct to say "practically" but not exactly Zero velocity. If we make it too hard to get to infinity how did they ever define the mass of a stationary electron. The electron rest mass (symbol: me) is the mass of a stationary electron. It is one of the fundamental constants of physics, If an electron was (a meter?? Unsure of actual distance) away from where it came from it would be in all intents be at infinity. I must refresh as to how they weighed a stationary electron. Link to comment Share on other sites More sharing options...
swansont Posted October 28, 2014 Share Posted October 28, 2014 "Virtually" I might have been more correct to say "practically" but not exactly Zero velocity. If we make it too hard to get to infinity how did they ever define the mass of a stationary electron. If an electron was (a meter?? Unsure of actual distance) away from where it came from it would be in all intents be at infinity. I must refresh as to how they weighed a stationary electron. Put it in a Penning trap and analyze the motion. Link to comment Share on other sites More sharing options...
MigL Posted October 29, 2014 Share Posted October 29, 2014 It seems to make sense to compare the EM potential well of an atom to the gravitational potential well of a planet, but things are not that simple at the quantum level. A 'higher' energy electron orbital is not necessarily further away from the nucleus than a 'lower' energy one. Orbitals are probability zones and not necessarily concentric spherical distributions ( some have 'lobes' and some even have a probability of occupying the nucleus ). Link to comment Share on other sites More sharing options...
Robittybob1 Posted October 29, 2014 Share Posted October 29, 2014 It seems to make sense to compare the EM potential well of an atom to the gravitational potential well of a planet, but things are not that simple at the quantum level. A 'higher' energy electron orbital is not necessarily further away from the nucleus than a 'lower' energy one. Orbitals are probability zones and not necessarily concentric spherical distributions ( some have 'lobes' and some even have a probability of occupying the nucleus ). Does it ever occupy the nucleus? Link to comment Share on other sites More sharing options...
swansont Posted October 29, 2014 Share Posted October 29, 2014 Does it ever occupy the nucleus? Electrons have some probability of being in the nucleus, especially those in the S shell. It gives rise to relatively large hyperfine splitting. Link to comment Share on other sites More sharing options...
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