why doesnt an electron get pulled in toward the nucleus?

Answer 1

Well, in terms of classical physics, an electron orbits the nucleus due to the electrical force. But the theory of electromagnetism tells us that accelerating charged particles lose energy, and anything which is orbiting something is accelerating. So, put these two facts together and the electron should lose energy and spiral into the nucleus. This obviously doesn't happen (if it did, there would be no atoms...), so this was a serious problem for physics in the first decade or so of the 20th century.

The semi-classical explanation, created by a physicist named Bohr to solve the problems with the classical explanation, proposed that electrons could only be in orbits where the quantity called angular momentum (which is numerically the momentum of a particle times the radius of its orbit, or formulaicly pr=mvr=m(r^2)w where w is the angular velocity [think of it as the frequency of the orbit]) was some integer number times a constant (called h-bar). This theory prevented the electron from falling into the nucleus of an atom, and it explained the Hydrogen atom perfectly. But it didn't work for any other kind of atom.

Finally, there's the quantum explanation, which emerged about ten/fifteen years or so after Bohr did his work. In quantum theory particles are represented by probability distributions called wavefunctions (which is, depending on how you approach it, either a result of or the reason for Heisenburg's Uncertainty Principle; also, I'm playing a bit fast and loose with my terminology: a wavefunction isn't a probability distribution, but if you basically square the wavefunction, that's the probability distribution). Now, if you work out the wavefunction of an electron around a nucleus, it turns out to be constant in time, which means that it doesn't fall into the nucleus (or fly off into space or whatever else; it stays around the nucleus as desribed by the wavefunction). Of course, one thing which is interesting to note is that in many situations (incluing the simplest) the signle point (though not the radius) where the probability of finding the electron is the highest is actually in the nucleus. :) But if you found the electron there at one moment the next moment you could easily find it outside the nucleus. It's random (as far as we know).

Now, if this last confuses you or seems weird, well, it *is* quantum mechanics, and quantum mechanics is renowned for being very weird and confusing. As to why you can never just find the electron always sitting in the nucleus of an atom, it basically has to do with the Uncertainty Principle. If you knew that the electron definitely had to be in the same place as the nucleus at any given point of time, you couldn't know how fast it was moving very well at all, so a moment later the electron could be very far away from the nucleus (but not separated from it, as the electrical attraction would still be there and would keep the electron from escaping the nucleus altogether).

I hope I've shed some light on this subject for you.

Answer 2

Because it is against the law. The law of quantum mechanics, that is. it is not centrifugal force, angular momentum or anything like that; that connot explain why the electron does not collapse into the nucleus. The electrons in an atom are restricted to certain energy levels (quantum levels) and are constrained to those levels. The closest an electron can get to the nucleus is the lowest energy level, which is never zero. You are not allowed to ask why. That's just the way the universe is built.

Answer 3

hznfrst is basically correct, except that the "ultraviolet catastrophe" is not the problem of the electron spiraling into the nucleus (it has to do with the false prediction of classical mechanics that radiated power goes to infinity as the frequency increases). However, both are addressed by the idea that energy and momentum are quantized. This means that there are intrinsic limitations on where an electron can be relative to the nucleus, so the classical equation for electrical force doesn't apply.

Answer 4

That's the question that led to the crisis in classical physics 100 years ago, which in turn led to quantum mechanics as the solution! A 'classical' electron would certainly spiral into the nucleus, but the leap was made that if energy only occured in discrete packets (called quanta) this 'ultraviolet catastrophe' as it was called would not happen.

This was a change in thinking at least as important as relativity, even though the two theories still remain entirely separate, which is really odd since they precisely describe different aspects of the same universe. So the search for a theory of everything continues.

Answer 5

It does. but the force pulling it act in such a way as to turn the direction of the velocity (which is a vector) and make the electron orbit the nucleus.

If you 'd an explanation with less classical physics try this one: If the electron "landed" on the nucleus, then we'd know both its velocity and its position, in which case Dr Heisenberg would be very displeased!

Answer 6

because the net charge between electron and proton are different.this different net charge is same as an earth is moving in and orbit of the sun. if the net charge is large, then the orbit will be more smaller than the higher net charge. result of the electron pulled towards the proton will cause the lose of energy in the nucleus but express out the energy out from the cell that leads to the mechanism of chain..just like atom bom.

Answer 7

Because they once were in a domestic union. But at a certain point they split up and the nucleus asked for a restraining order. Now the electron just drives around and can't get near.

Answer 8

an electron doesnt get pulled into da nucleus just because electrons move around the nucleus in specific energy levels, it neds a lot of energy to move from one energy level to another....it takesin energy to move to the next higher level or releases energy to go to a lower energy level,However it is still a draww back of sommerfield's atomic model....when a eletron moves around the nucleus we assume that it doesnt loose or gain any energy !!! we can also use the concept of Circular Motion

Answer 9

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Answer 10

Centrifugal force keeps the electron from falling into the nucleus.