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Author Topic: How electrons know where to go in atoms?  (Read 1908 times)

Offline Yahya A. Sharif

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How electrons know where to go in atoms?
« on: 27/08/2016 19:38:02 »
 how an electron can return to its accurate precise orbit and to its rotating speed during electrolysis , when a positive ion gains an electron to become an atom again ? I can't see anyhow to make it return again.
« Last Edit: 01/09/2016 08:28:29 by chris »


 

Offline evan_au

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Re: how does an electron return to its orbit?
« Reply #1 on: 28/08/2016 05:45:56 »
Negative electrons are attracted to the positive charge of a nucleus (as expressed by a positive ion), forming a neutral atom or molecule.
Negative electrons are also attracted to unpaired electrons, forming a negative ion (atom or atomic group).
Both processes involving an electron returning to an orbit occur during electrolysis (as do the reverse processes of an electron leaving its orbit).

An electron does not return to exactly the same atom it left - in electrolysis, it is likely to return to a different atom, and quite possibly to a different kind of atom - perhaps one in the wire, rather than an atom in the electrolysis solution.

Even if an electron returns to the same kind of atom, it doesn't necessarily return to the same orbital it left. Electrons are pretty interchangeable, and interchange all the time.

Electrons in a solution don't have an absolutely precise energy - the energy is influenced by the surrounding atoms. And they don't have a precise orbital speed - it's more a probability of finding an electron in a particular position relative to the nearby atom(s).
 

Offline Yahya A. Sharif

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Re: how does an electron return to its orbit?
« Reply #2 on: 28/08/2016 13:13:08 »
why an electron stuck on an orbit instead of falling on the nucleus ? satellites are put on orbits by a complicated process  ,the intuitive thing is that they should just be attracted and fall onto the nucleus ,  is there any special process to put electrons back again in orbits? can this be a random process or intelligent directed one? and how a random process will manage to make something like this?
« Last Edit: 28/08/2016 13:17:01 by Yahya A. Sharif »
 

Offline chiralSPO

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Re: how does an electron return to its orbit?
« Reply #3 on: 28/08/2016 17:59:16 »
Electrons do not actually "orbit" the nucleus in the same way that a satellite orbits a planet.

It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground, but still measurably extends more than 100 km from the surface. No intelligent direction is required for the effect to manifest in either case.

 
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Offline jeffreyH

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Re: how does an electron return to its orbit?
« Reply #4 on: 28/08/2016 18:42:58 »
Electrons do not actually "orbit" the nucleus in the same way that a satellite orbits a planet.

It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground, but still measurably extends more than 100 km from the surface. No intelligent direction is required for the effect to manifest in either case.

I have to say, that is a description that I like a lot. No messing. Just to the point.
 

Offline chiralSPO

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Re: how does an electron return to its orbit?
« Reply #5 on: 28/08/2016 19:28:44 »
Electrons do not actually "orbit" the nucleus in the same way that a satellite orbits a planet.

It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground, but still measurably extends more than 100 km from the surface. No intelligent direction is required for the effect to manifest in either case.

I have to say, that is a description that I like a lot. No messing. Just to the point.

Thanks! :-D
 

Offline Yahya A. Sharif

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Re: how does an electron return to its orbit?
« Reply #6 on: 28/08/2016 20:06:31 »
It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground.....
does that mean there is a probability of even 1% for an electron to actually fall onto the nucleus and stuck on it during electrolysis ? if many electrons stuck on the nucleus , it may become neutral in charge and no more electrons will orbit it .
 

Offline chiralSPO

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Re: how does an electron return to its orbit?
« Reply #7 on: 28/08/2016 20:42:10 »
It is entirely reasonable to say that an electron in an atomic orbital *has* fallen all the way to the central nucleus. It just so happens that electrons are effectively fluffy, and spread out over a volume 100,000 times larger that that occupied by the nucleus. Similar to how the atmosphere on Earth has fallen all the way down to the ground.....
does that mean there is a probability of even 1% for an electron to actually fall onto the nucleus and stuck on it during electrolysis ? if many electrons stuck on the nucleus , it may become neutral in charge and no more electrons will orbit it .

Well, that's basically what an atom is: enough electrons stuck to a nucleus that the whole thing is neutral (no electrolysis required). The reality is slightly more complex than that because the electrons interact with each other as well as with the nucleus, and the whole atom is so small that one has to take quantum mechanics into consideration.
 

Offline Yahya A. Sharif

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Re: how does an electron return to its orbit?
« Reply #8 on: 30/08/2016 17:04:16 »
what makes electrons not to stuck on a nucleus during electrolysis , according to quantum mechanics? there should be electrostatic force of attraction , if they are going to orbit around then the force exists , what makes that not to happen according to QM?
 

Offline chiralSPO

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Re: how does an electron return to its orbit?
« Reply #9 on: 30/08/2016 19:44:53 »
Please re-read my earlier comments on this thread. There is no force keeping an electron away from the nucleus. An electron in an atom IS stuck to the nucleus, it just happens to take up much more space than the nucleus.

It could be that you are confused by this simplistic Bohr model of an atom:

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj9htXb5OnOAhXLuB4KHQfZBdkQjRwIBw&url=http%3A%2F%2Fchemistry.tutorcircle.com%2Finorganic-chemistry%2Fbohr-model.html&psig=AFQjCNEkNS6nbqp7gCdPJt4JLyly0h_Egw&ust=1472668730459570

This picture is NOT an accurate depiction!


Instead it is more realistic to think of electrons as being spread out in the volume around the nucleus:
https://www.google.com/imgres?imgurl=http%3A%2F%2Fwps.prenhall.com%2Fwps%2Fmedia%2Fobjects%2F3081%2F3155040%2Fblb0606%2F6.20.gif&imgrefurl=http%3A%2F%2Fwps.prenhall.com%2Fwps%2Fmedia%2Fobjects%2F3081%2F3155040%2Fblb0606.html&docid=r-4OOAFFC8uqWM&tbnid=Eqpdzk0Y4v7hgM%3A&w=520&h=325&bih=758&biw=1384&ved=0ahUKEwii5KOp5enOAhXBL8AKHTOSAaYQMwgeKAAwAA&iact=mrc&uact=8

Notice that in these three pictures of different orbital types, a majority of the electron distribution is very close to the nucleus, and tails off further and further away from the nucleus (very much like my atmosphere analogy). The gaps "nodes" are an interference effect, and not representative of any repulsive force.
 

Offline evan_au

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Re: how does an electron return to its orbit?
« Reply #10 on: 30/08/2016 23:00:33 »
Quote from: Yahya A. Sharif
does that mean there is a probability of even 1% for an electron to actually fall onto the nucleus and stuck on it during electrolysis ?
There is a process of radioactive decay called electron capture: An electron which is close to the nucleus is captured by a proton in the nucleus, which is converted to a neutron, emitting a neutrino.

This is only energetically favourable in atomic nuclei with too many protons for the number of neutrons. Reducing the number of protons by 1 and increasing the number of neutrons by 1 increases the stability of the nucleus.

An example is the decay of Potassium (K 40) to Argon (Ar 40), which is important for Potassium-Argon dating.

However, this is a nuclear process involving electrons, which is distinct from the chemical processes involving electrons, as described by ChiralSPO.
- Chemical processes involving electrons are governed by the Electromagnetic force, and typically happen on a timescale much smaller than nanoseconds.
- Electron capture is governed by the Weak Nuclear force, which (as the name suggests) is comparatively weak. K 40 decay occurs on a timescale of a billion years.

See: https://en.wikipedia.org/wiki/Electron_capture

Pons & Fleischman did an electrolysis experiment in which they claimed that nuclear-type processes were occurring, at room temperature. Even then, it was only claimed to occur less than 1% of the time. Unfortunately, this has been impossible to reproduce under controlled conditions, and is now dismissed by serious scientists.
 

Offline Yahya A. Sharif

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Re: how does an electron return to its orbit?
« Reply #11 on: 31/08/2016 07:35:44 »
in the image I can see an intensive collection of electrons , perhaps they are thousands , I do not think there is an atom with this intensive number of electrons , or what about a hydrogen atom with only one electron ? if we have around earth vacuum and there is only one oxygen molecule , it will fall to earth , and won't move , it will have a zero distance between it and earth surface ,  if something is stuck on something the distance between them is zero they touch , that what I mean by being stuck , which means the diameter of an atom is close or equal to the diameter of a nucleus , however , Bohr radius is not zero for a hydrogen atom because if that is the case an electron won't rotate. if there is a Bohr radius in hydrogen atom which is distance between electron and nucleus , this distance can be reduced or should be reduced due to electrostatic force to be zero , and that what should happen during electrolysis.
« Last Edit: 31/08/2016 07:47:51 by Yahya A. Sharif »
 

Offline puppypower

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Re: how does an electron return to its orbit?
« Reply #12 on: 31/08/2016 12:13:03 »
The orbits of the electrons are call orbitals. The orbitals or orbits are not all the same. As electrons are added to atoms, there is a sequence in terms of the orbital or orbit for each electron. Below is a diagram of the orbital shapes.

The orbital shapes and locations in space are dependent on the magnetic addition of the electrons. A charge in motion will create a magnetic field. With all the electrons of an atom orbiting; in motion, and creating their own magnetic fields, they cooperate by each assuming an orbit that allows its magnetic field to add with the magnetic fields of the others. This results in pre-defined shapes and electron addition sequences.

Oxygen can form oxide or O-2, wth the magnetic addition of all these electrons, able to overcome the electrostatic repulsion of having two extra electrons in orbit. This show how important magnetic addition is when it comes to assigning orbits to electrons. Metals often lose one or more electrons, usually to oxygen in an attempt to further maximize magnetic addition in atomic systems.

 
 

Offline chiralSPO

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Re: how does an electron return to its orbit?
« Reply #13 on: 31/08/2016 16:51:12 »
in the image I can see an intensive collection of electrons , perhaps they are thousands , I do not think there is an atom with this intensive number of electrons , or what about a hydrogen atom with only one electron ? if we have around earth vacuum and there is only one oxygen molecule , it will fall to earth , and won't move , it will have a zero distance between it and earth surface ,  if something is stuck on something the distance between them is zero they touch , that what I mean by being stuck , which means the diameter of an atom is close or equal to the diameter of a nucleus , however , Bohr radius is not zero for a hydrogen atom because if that is the case an electron won't rotate. if there is a Bohr radius in hydrogen atom which is distance between electron and nucleus , this distance can be reduced or should be reduced due to electrostatic force to be zero , and that what should happen during electrolysis.

The dots are not representative of individual electrons. All of those dots indicate the distribution of *one* electron.

If the entire atmosphere contained only one molecule, it would not necessarily be stuck to the ground. The molecule would have kinetic energy, and would therefore move around (its altitude would change as well as its latitude and longitude). If the kinetic energy were large enough, it could actually escape from Earth's gravitational pull. If the kinetic energy were very small, then yes, it could be stuck to the ground (not gaseous).

This is where the analogy breaks down. It is not possible for the electron to have zero kinetic energy and be stuck to the nucleus. The 1s orbital represents the minimum energy state of the electron in an atom.
 

Offline Yahya A. Sharif

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Re: how does an electron return to its orbit?
« Reply #14 on: 01/09/2016 07:54:21 »
an object on the surface of earth is capable to obtain an orbit around if the object has enough kinetic energy , but the opposite is impossible , an object coming from space towards earth planet will just hit it and stuck on its surface , that is not because this object has kinetic energy or not , in fact it has but it is not intelligently directed , I may be able to walk a mile , I have the efficient energy , but there are four walls that keeping me inside , if I did not intelligently find a ladder and climbed my energy will not be enough to enable me to walk this mile, the electron has energy coming through a wire , but energy is not enough, I can't see anyhow for it to obtain an orbit again , with the same 1st orbital energy and the same Bohr radius . if electrons orbiting is a natural phenomenon , how it could return back if it ruins? I always thought of the atom model as being ridiculous .
 

Offline chiralSPO

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Re: How electrons know where to go in atoms?
« Reply #15 on: 01/09/2016 17:26:40 »
Maybe instead of comparing to a satellite orbiting a planet, try thinking of the nucleus as a tennis ball, and the electron as water. It doesn't matter how many times you dry the tennis ball, or how long it has been dry, when you dunk it in water, it always turns into a wet tennis ball. And once it has gotten wet, I don't think you would be able to distinguish what the dry/wet history of the ball had been (ie each wet tennis ball is the same as any other wet tennis ball). Is it magic that the balls get the same amount wet? No, the amount of water that sticks to a tennis ball is relatively constant from time to time.

Or think of filling a jar with marbles. It doesn't matter how you put the marbles in, the jar can only hold a certain numbers of marbles, and you would not be able to know anything about how the marbles went in based on looking at a full jar.

Similarly, each nucleus will attract a certain amount of electron. You can forcibly remove the electrons, but when you put them back, they go to the right place.
 

Offline Yahya A. Sharif

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Re: How electrons know where to go in atoms?
« Reply #16 on: 02/09/2016 09:25:17 »
the situation is :
we have a single electron orbiting in an ellipse , it has a mass , it has a centripetal force , the force is field-based one , it has a certain radius of rotation , the only centrifugal force is its motion , it does not touch the nucleus   , it is capable to jump from orbit to orbit or return back .

when I compare it by a satellite I compare it according to the above situation:
a single satellite orbiting in an ellipse , it has a centripetal force , the force is field-based one , it has a certain radius of rotation , the only centrifugal force is its motion , it does not touch the planet  , it is capable to jump from orbit to orbit or return back.

when compared it to the  atmosphere , the analogy soon failed for a single electron  , because that is not reality , electrons are not a collection of billions of molecules in away that they cover from the earth surface to 100 km distance !the molecules are very close to each other , in away that if you want to make them closer you need high pressure, that why they move and not stuck on earth ,  because there  is a reserved place for each one , because they are just like a queue one above the other , you  do not need to put them intelligently in a certain place because they already filled all the place in a form of a queue , in comparison electrons are not , for water in a tennis ball , you are right and agree with me , that what is going to happen , a number of electrons will stuck on a nucleus , and won't be able to move freely , just like water molecules on a tennis ball , for the marbles jar I think that is the only thing to save the situation , a ring pipe with hole in it , electrons enter in side it to rotate in their accurate Bohr radius , is there a ring pipe in an atom ? NO.

 
« Last Edit: 02/09/2016 10:45:34 by Yahya A. Sharif »
 

Offline Yahya A. Sharif

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Re: How electrons know where to go in atoms?
« Reply #17 on: 02/09/2016 18:55:59 »
electrons may be very tiny , but they have mass , speed and kinetic energy , they move from orbital to another , they are attracted by electrostatic force , their rotation is governed by elliptical and circular motion laws like centripetal force , according to all these laws there is not a way for them to know their place  in an atom just with their kinetic energy.
 

Offline chiralSPO

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Re: How electrons know where to go in atoms?
« Reply #18 on: 02/09/2016 22:11:13 »
no, not just kinetic energy.

But, using four parameters (the four quantum numbers of each electron: n, l, ml and ms we can describe the distribution and symmetry of the electron's orbital.

I agree that electrons have mass. Their mass relative to the mass of the nucleus is central to the description of an atom. Because the electron has 1/1836 the mass of a single proton, the de Broglie wavelength (and hence the spatial confinement) of the electron is significantly longer (more space) than that of the proton.

Look, I understand that this is not intuitive, and in fact is largely counter-intuitive based on macroscopic analogies. But at the end of the day we must rely on what observation tells us. The electrons *do* go back exactly where they came from. Our understanding of this is from the culmination of tens of thousands of experiments run by thousands of scientists over the last two hundred years. If you want to say that it must be directed by an intelligence, fine. Then you can think of science as a description for how that intelligence directs the physical world.
 

Offline evan_au

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Re: How electrons know where to go in atoms?
« Reply #19 on: 03/09/2016 00:01:38 »
Quote from: Yahya A. Sharif
the opposite is impossible , an object coming from space towards earth planet will just hit it and stuck on its surface
If a small object approaches the Earth or the Sun from deep space, it will fling around and head back out to deep space, in an hyperbolic "orbit". It is not elliptical, and it will never return.

To move into an elliptical orbit, the object from space has to lose energy somehow - either by a space probe firing rockets, or a comet using a gravitational slingshot around Jupiter, etc. (Or by radiating gravitational waves - but this effect is so slight that it's only relevant for colliding black holes.)

Similarly, for an electron to move into an orbital, it must lose energy. Since the electromagnetic force is much stronger than the gravitational force, it's actually very easy for an electron to radiate its energy as a photon (electromagnetic wave) and drop into an orbital. 

Note that the orbitals of an electron are not elliptical - they are shaped by the location of the other nearby electrons (again via this extremely strong electromagnetic force, plus the wave nature of the electron).
Planetary orbits are not elliptical either, when you have many strong gravitational tugs (eg the orbit of Pluto's dense flock of moons, or some of the dense exoplanet systems discovered by the Kepler space mission).

While the wave nature of planets and moons can be ignored, you can't ignore the wave nature of an electron.
 

Offline evan_au

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Re: How electrons know where to go in atoms?
« Reply #20 on: 03/09/2016 01:49:53 »
Quote from: Yahya A. Sharif
an object coming from space towards earth planet will just hit it and stuck on its surface
Another aspect of this discussion....

As far as we know, an electron is an elementary particle - it has no interior structure, and no incompressible minimum size.
- The electron is a radically different particle than the proton, and it doesn't interact with the proton (except by the electromagnetic force, which they both feel).
- So it's actually quite possible for an electron to exist inside a proton or pass through a proton with no adverse effects - without "hitting" or "sticking" - and without staying there.

On the other hand, the Earth and a Meteorite are not fundamental particles - they are both made of the same stuff (atoms), which interact strongly with each other. The atoms are extended objects which can't pass through each other without severe disruption. They will "hit" and get "stuck on its surface".

An interesting application of this lack of interaction between electron and proton is measuring the radius of the proton's electric charge.
- In Hydrogen, there is a small chance that an electron will be inside the proton
- It is possible to hit Hydrogen with a laser beam of the right frequency, and measure the energy required to boost the electron's energy into another orbital which does not enter the proton.
- There is another particle, the Muon, which is somewhat like an electron, only it is 207 times the mass of the electron.
- The Muon orbital radius around the proton is 207 times smaller than the electron, so it is very likely to be found inside the proton.
- It is possible to hit this "Muonium" with a laser beam, and measure the energy required to boost the Muon's energy into another orbital which does not enter the proton.

It is one of the unsolved problems in physics that the inferred radius of the proton is different depending on whether you measure it with Electrons or Muons.

See: https://en.wikipedia.org/wiki/Muon#Use_in_measurement_of_the_proton_charge_radius
 

Offline jeffreyH

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Re: How electrons know where to go in atoms?
« Reply #21 on: 03/09/2016 12:36:22 »
In considering extended objects we can turn to Newton's second law which can predict the motion of the centre of mass of an object even if it is rotating. All wee need to know are the force vectors applied to the object. If we consider both the proton and electron as extended objects at the microscopic scale then the force vectors are derived from the electromagnetic and weak force interactions. The masses of the muon and electron, being different, will have distinctly different centres of mass which will result in different proton radius measurements as they move through the fields.
 

Offline Yahya A. Sharif

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Re: How electrons know where to go in atoms?
« Reply #22 on: 03/09/2016 19:24:41 »
you can think of science as a description for how that intelligence directs the physical world.
I like this expression . I think so , but I thought this intelligence won't be achieved by a planetary model. may be I should post this thread hundred years ago.
« Last Edit: 03/09/2016 19:44:15 by Yahya A. Sharif »
 

Offline alancalverd

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Re: How electrons know where to go in atoms?
« Reply #23 on: 03/09/2016 22:58:56 »
It's all down to indeterminacy. There is a limit to the precision with which the momentum and position of a particle can be determined dp.dx = h/2(pi) where dp and dx are the indeterminacies of mometum and position respectively, h is Planck's constant (an experimental value) and (pi) is the number we usually represent with a Greek symbol that I can't insert because the forum software is screwed up!

Now the nucleus is very small, so if an electron were to be inside the nucleus,  we would know exactly where it was so dx would vanish and dp would be enormous. Since p is the product of mass and velocity, and mass is fixed, that would mean that if an electron approached the nucleus its velocity would increase enormously, so it couldn't stay there very long.

At the other extreme, the electrostatic attraction between an electron and a nucleus means that you are more likely to find electrons near nuclei than a long way from them.

Thus we can construct a picture of the probability of finding an electron, as a function of distance from a nucleus. In the simplest case of hydrogen, that looks like a fuzzy spherical shell with a maximum density at about 5.2 x 10^-11 m from the nucleus. The equations get more complicated as you add more protons and electrons, but the orbitals shown in reply #12 above are solutions to the equations in 3 dimensions (the rest of that post is mostly nonsense - for instance orbitals are NOT orbits!) and are confirmed by experiment.
 
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Re: How electrons know where to go in atoms?
« Reply #23 on: 03/09/2016 22:58:56 »

 

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