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Escaping electrons...

by I2004
Tags: electrons, escaping
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I2004
#1
Dec13-12, 07:43 AM
P: 57
how easy is it for an electron to escape the nucleus of an atom and how often does it happen?

say we have an atom of carbon, how often will it shed/share or swap an electron, or how often will an electron escape in an average time frame?
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K^2
#2
Dec13-12, 03:16 PM
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P: 2,470
You mean the electrons in atomic orbitals? "Electron to escape nucleus," makes it sound like you want it to actually originate from nucleus, which will only happen in beta-minus decay. Carbon is stable, so no electrons leaving the nucleus. The shell is another matter, however.

In organic molecules, the valence electrons tend to shift around. They aren't really bound to a specific carbon.

If you are interested in a free carbon atom, then you need to look at first ionization energy. For Carbon, it's 11.26 eV. Thermal fluctuations at room temperatures are on the order of 0.025 eV. That results in probability of electron leaving a carbon atom being so low that it might as well be zero.
I2004
#3
Dec13-12, 03:42 PM
P: 57
In organic molecules, the valence electrons tend to shift around. They aren't really bound to a specific carbon.

but you would say they dont leave the compound? how often/how likely would these electrons in the compound likely get annihilated by anti-electrons?

Drakkith
#4
Dec13-12, 04:14 PM
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Escaping electrons...

Quote Quote by I2004 View Post
but you would say they dont leave the compound? how often/how likely would these electrons in the compound likely get annihilated by anti-electrons?
Practically never. Positrons (Anti-electrons) aren't common. They are actually created all the time by cosmic rays colliding with matter here on Earth, but in such low amounts compared to the amount of normal matter than any individual electron would effectively never meet one in any realistic time frame.
sophiecentaur
#5
Dec13-12, 04:41 PM
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Thanks
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In metals, the outer electrons are completely unattached to particular atoms but constantly zap around at very high average speeds.
K^2
#6
Dec13-12, 05:32 PM
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Quote Quote by I2004 View Post
how often/how likely would these electrons in the compound likely get annihilated by anti-electrons?
Are you talking about electrons as quasi-particles, which is the particle in a more classical sense? Or are you continuing the line of questions you had about creation-annihilation in field theory?
Khashishi
#7
Dec14-12, 10:54 AM
P: 887
You need some kind of collision or absorption to take place for an atom or molecule to lose an electron and become ionized. So, it depends on what kind of collisions take place. In a plasma, the ionization rate depends on the number density of each particle species and energy distribution of each species and any incoming radiation. The higher the density, the more ionizing collisions. In plasmas where the ion temperature is not much greater than the electron temperature, the electrons move much faster than nuclei, so electron-ion collisions may be the dominant ionizing contribution.
Molecules could also be ionized by UV or x-rays.

To calculate the rates, you need the cross sections, which are tabulated for some elements, but the data are not very accurate or complete, especially for heavier elements.
I2004
#8
Dec14-12, 06:00 PM
P: 57
Quote Quote by Khashishi View Post
You need some kind of collision or absorption to take place for an atom or molecule to lose an electron and become ionized. So, it depends on what kind of collisions take place. In a plasma, the ionization rate depends on the number density of each particle species and energy distribution of each species and any incoming radiation. The higher the density, the more ionizing collisions. In plasmas where the ion temperature is not much greater than the electron temperature, the electrons move much faster than nuclei, so electron-ion collisions may be the dominant ionizing contribution.
Molecules could also be ionized by UV or x-rays.

To calculate the rates, you need the cross sections, which are tabulated for some elements, but the data are not very accurate or complete, especially for heavier elements.
cheers!!!


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