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Thread: electron orbitals

  1. #1 electron orbitals 
    Forum Masters Degree SuperNatendo's Avatar
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    What keeps the electron's orbit around the nucleus from slowing down?

    In planetary orbits, the speed changes, do similar things happen in electron orbits?


    "It's no wonder that truth is stranger than fiction. Fiction has to make sense." - Mark Twain
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  3. #2 Re: electron orbitals 
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    Quote Originally Posted by SuperNatendo
    What keeps the electron's orbit around the nucleus from slowing down?

    In planetary orbits, the speed changes, do similar things happen in electron orbits?
    I was taught that electrons do not orbit. But rather race through atoms. Keeping them the tight little balls of electrons I was taught they were.

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    William McCormick


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    If the electron loses speed, its kinetic energy, and hence total energy, decreases. However, the Bohr model of the atom assumes that the electron cannot lose or gain a continuous amount of energy; the energy it receives or emits must be in discrete (quantum) amounts. The electron therefore has different discrete energy levels (the lowest energy level being called the ground state).

    An explanation of why the energy levels are as they are is due to the wave–particle duality. The electron, though a particle, has an associated de Broglie wavelength. If the circumference of a particular orbit is an integer multiple of half of the electron’s de Broglie wavelength, then a standing wave results – which should help to conserve the electron’s energy in that orbital.

    Well, that’s my understanding anyway. 8)
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    So, in other words, due to quantum theory, the electrons orbit is constantly gaining and losing kinetic energy to keep it at a somewhat stable speed. And the electron just as a photon exists as both a particle and a wave?

    So are you saying quantum theory allows for Perpetual motion? How could that be? I don't understand this at all.

    How fast are electrons supposed to travel? I know that in water, the light actually travels slower than the electron through the meduim of water. If the orbital of the electron equals the speed of light it will have to be massless just as a photon is said to be, but electrons supposedly have mass.

    I'm getting really confused here.
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    Not so much perpetual motion as a closed-loop standing wave.

    http://en.wikipedia.org/wiki/Standing_wave
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    but eventually, these waves should lose kinetic energy right? Isn't closed-loop just a fancy way of saying "Perpetual Motion"?
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    What do you mean by “perpetual motion”? Isn’t Newton’s first law of motion a case of “perpetual motion”?
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    Well, yes, yes it is.

    I guess what people mean when they say perpetual motion is not possible is not really talking about perpetual motion but rather perpetual motion even when encountered by friction.

    So as long as the electron does not meet any friction, it will keep going, And the only way it could meet friction is by a subatomic particle, since electrons always repel each other.

    So, theoretically, if you blasted an atom with subatomic particles, you would eventually slow the electron's orbit? Or if you made a strong-enough positive electro-magnetic field, could you break the bond between the nucleus and the electron?
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    Much of your confusion arises from failing to distinuish between orbits and orbitals. They are quite different.

    Saying an electron is in orbit treats the atom as a miniature solar system. We now know this picture is false. Even Neils Bohr, who "proved" this was the case for hydrogen in 1913, abandoned this model soon thereafter. The solar-system model was rendered totally obsolete by the mid-1920s by the development of quantum mechanics. Still, the solar-system model stil survives in our imaginations, perhaps because the average person finds it easy to grasp and need know nothing more.

    The quantum model depends on orbitals, which are regions of probable locations of an electron. Nothing is said about their motion. They do NOT necessarily whirl round and round the nucleus. More importantly, these electrons do not obey the laws of classical physics, which is exactly what you are trying to make them do in your questions.

    That renders most of your questions meaningless. For example,

    So, theoretically, if you blasted an atom with subatomic particles, you would eventually slow the electron's orbit?
    No, because it isn't 'orbiting.' You might be able to kick the electron up to a higher orbital, however, or blast it away completely.

    Or if you made a strong-enough positive electro-magnetic field, could you break the bond between the nucleus and the electron?
    This is called ionization and it's not particularly hard to do. One familiar example is the creation of static electricity. Another case would be dissolving a salt crystal in water, creating ions. Or shining light on a photocell, and so on.

    In general, I advise you to abandon the solar-system model when considering the effects of incident energy on the atom. Best to think in terms of energy levels.
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    Quote Originally Posted by SteveF
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    Much of your confusion arises from failing to distinuish between orbits and orbitals. They are quite different.

    Saying an electron is in orbit treats the atom as a miniature solar system. We now know this picture is false. Even Neils Bohr, who "proved" this was the case for hydrogen in 1913, abandoned this model soon thereafter. The solar-system model was rendered totally obsolete by the mid-1920s by the development of quantum mechanics. Still, the solar-system model stil survives in our imaginations, perhaps because the average person finds it easy to grasp and need know nothing more.

    The quantum model depends on orbitals, which are regions of probable locations of an electron. Nothing is said about their motion. They do NOT necessarily whirl round and round the nucleus. More importantly, these electrons do not obey the laws of classical physics, which is exactly what you are trying to make them do in your questions.

    That renders most of your questions meaningless. For example,

    So, theoretically, if you blasted an atom with subatomic particles, you would eventually slow the electron's orbit?
    No, because it isn't 'orbiting.' You might be able to kick the electron up to a higher orbital, however, or blast it away completely.

    Or if you made a strong-enough positive electro-magnetic field, could you break the bond between the nucleus and the electron?
    This is called ionization and it's not particularly hard to do. One familiar example is the creation of static electricity. Another case would be dissolving a salt crystal in water, creating ions. Or shining light on a photocell, and so on.

    In general, I advise you to abandon the solar-system model when considering the effects of incident energy on the atom. Best to think in terms of energy levels.
    There is no bond between the nucleus of the atom and electrons around the nucleus. They are totally pushing away from one another already.


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    William McCormick
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    Quote Originally Posted by William McCormick
    There is no bond between the nucleus of the atom and electrons around the nucleus. They are totally pushing away from one another already.
    The negatively charged electrons are attracted by the positively charged nucleus. Therefore, the potential energy is lower when the electron in the ground state, i.e. closest to the nucleus. Otherwise it would not be possible to emit the photons whose energy is provided by the difference in potential energy when falling to a lower orbital.
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    i read somewhere about the word "electron clouds"
    in that the electron isn't as much orbiting the nucleus, but more a cloud of probability that breaks down into a particle once it is attempted to be observed. (ala the double-slit experiment)

    so when it is not being observed, it creates an interference pattern, like a propagating wave, and when its observed, it creates 2 lines.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
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    Quote Originally Posted by dejawolf
    i read somewhere about the word "electron clouds"
    in that the electron isn't as much orbiting the nucleus, but more a cloud of probability that breaks down into a particle once it is attempted to be observed. (ala the double-slit experiment)

    so when it is not being observed, it creates an interference pattern, like a propagating wave, and when its observed, it creates 2 lines.
    Yes, "electron clouds" is used in order to oppose the common idea about electrons being solid bullet like particles. It describes the areas of high probabilities where the electron is located. Since the "uncertainty principle" does not allow to determine both the location and the velocity of a particle with a high accuracy, we can locate the electrons with a low precision only, leading to the picture of probability clouds.

    The double slit experiments is of course carried out with a beam of electrons (or a single free electron) hitting the slits, but not with ones being bound to an atom.
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    Quote Originally Posted by Dishmaster
    Quote Originally Posted by William McCormick
    There is no bond between the nucleus of the atom and electrons around the nucleus. They are totally pushing away from one another already.
    The negatively charged electrons are attracted by the positively charged nucleus. Therefore, the potential energy is lower when the electron in the ground state, i.e. closest to the nucleus. Otherwise it would not be possible to emit the photons whose energy is provided by the difference in potential energy when falling to a lower orbital.
    That is just a misconception. That can easily not be proven.


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    William McCormick
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  16. #15  
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    Quote Originally Posted by William McCormick
    Quote Originally Posted by Dishmaster
    Quote Originally Posted by William McCormick
    There is no bond between the nucleus of the atom and electrons around the nucleus. They are totally pushing away from one another already.
    The negatively charged electrons are attracted by the positively charged nucleus. Therefore, the potential energy is lower when the electron in the ground state, i.e. closest to the nucleus. Otherwise it would not be possible to emit the photons whose energy is provided by the difference in potential energy when falling to a lower orbital.
    That is just a misconception. That can easily not be proven.


    Sincerely,


    William McCormick
    wrong, this can easily be proven, and even measured, and so real scientists have.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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  17. #16  
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    Quote Originally Posted by William McCormick
    Quote Originally Posted by Dishmaster
    Quote Originally Posted by William McCormick
    There is no bond between the nucleus of the atom and electrons around the nucleus. They are totally pushing away from one another already.
    The negatively charged electrons are attracted by the positively charged nucleus. Therefore, the potential energy is lower when the electron in the ground state, i.e. closest to the nucleus. Otherwise it would not be possible to emit the photons whose energy is provided by the difference in potential energy when falling to a lower orbital.
    That is just a misconception. That can easily not be proven.


    Sincerely,


    William McCormick
    what is the misconception?
    Beyond Equations,

    Pritish
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