Why does an electron not fall into the nucleus?

In summary, the electron has less mass and is a point object which prevents it from falling into the nucleus due to attraction of protons.
  • #1
avito009
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4
Is it because the electron has less mass and is a point object that prevents it from falling into the nucleus due to attraction of protons?
 
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  • #2
At the atomic level the electron is not a classical point object which can be thought of as "falling". It is described by quantum physics and it cannot be in a lower energy state than the ground state.
 
  • #3
I read that

In quantum physics there is something called "the uncertainty principle" that states that we can't know where something is at the same time as we know where it's going (due to it being a wave). Or rather, the better known somethings position is, the less known is it's movement.

Now, with this knowledge we can determine what happens if an electron actually "fell" into the nucleus. The position would be well known (it's in the nucleus), but that means it could be moving really fast, so it breaks free from the nucleus again. This means it can't actually fall in.Why we can't know where something is at the same time as we know where it's going due to it being a wave. How does being a wave effect this?
 
  • #4
avito009 said:
Now, with this knowledge we can determine what happens if an electron actually "fell" into the nucleus. The position would be well known (it's in the nucleus), but that means it could be moving really fast, so it breaks free from the nucleus again. This means it can't actually fall in.
You need to stop using the word "fell", even within quotes. What you are describing is only a semiclassical and popular interpretation of quantum physics. The point is that if the electron was localised to the nucleus, it would be in a superposition of states which includes several non-bound states as well as some bound states which are bound but not the ground state. The time evolution of the wave function would quickly result in the electron most likely being somewhere else.

avito009 said:
Why we can't know where something is at the same time as we know where it's going due to it being a wave. How does being a wave effect this?
This is also a popular misconception. Particles in quantum physics are not waves, nor are they tiny balls (i.e., classical particles). They have some properties reminiscent of these objects, but they really are quantum particles. The non-localisability of a quantum particle follows directly from the commutation relation between the position and momentum operators.
 
  • #5
Before going into the millionth near-identical copy of this thread, may I point out that this is the https://www.physicsforums.com/threads/why-dont-electrons-crash-into-the-nucleus-in-atoms.511179/ in the https://www.physicsforums.com/threads/physics-faq-list.807553/ .
 
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  • #6
I can understand that the electrons orbit the nucleus because there is a centripetal force exerted on the electrons. This centripetal force is due to the attractive force of the protons. But if we observe the Earth which orbits the sun. There is an initial momentum which stops Earth from moving into the sun. Does the electron also have some initial momentum?
 
  • #7
Vanadium 50 said:
Before going into the millionth near-identical copy of this thread, may I point out that this is the https://www.physicsforums.com/threads/why-dont-electrons-crash-into-the-nucleus-in-atoms.511179/ in the https://www.physicsforums.com/threads/physics-faq-list.807553/ .

That's another topic. This question is not about a loss of energy doe to emission of EM-radiation but about an electron "falling" into the nucleus of an atom. The answer is, that the probability density of the electron is not zero in the nucleus of an atom and for s-electrons it even reaches its maximum in the center. Thus an electron can "fall" into the nucleus and proton-rich nuclei can capture it.
 
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  • #8
avito009 said:
Does the electron also have some initial momentum?
It is possible for an electron to have an orbital with orbital angular momentum, but there are also orbitals without orbital angular momentum, called s orbitals. Since there are some orbitals without angular momentum, angular momentum is not the thing which prevents the electron from being confined to the nucleus.

In the end, it is just about energy. It would take a lot of energy to confine the electron to the nucleus. So instead it relaxes to a lower energy state where the electron is not confined to the nucleus.
 
  • #9
Thread locked, pending possible moderation.
 
  • #10
After discussion the thread will remain locked and several off topic posts have been removed.
 

FAQ: Why does an electron not fall into the nucleus?

1. Why does an electron not fall into the nucleus?

The electron does not fall into the nucleus because of the natural repulsive force between negatively charged particles. The electron is constantly moving around the nucleus in a specific energy level, and the balance between its kinetic energy and the attractive force of the nucleus keeps it from falling in.

2. What is the role of the electric force in keeping the electron from falling into the nucleus?

The electric force is the fundamental force responsible for keeping the electron from falling into the nucleus. This force is created by the attraction between the positively charged protons in the nucleus and the negatively charged electron. It is this force that balances the gravitational pull of the nucleus and keeps the electron in orbit.

3. Can an electron ever fall into the nucleus?

No, an electron cannot fall into the nucleus. According to the laws of quantum mechanics, electrons can only exist in specific energy levels around the nucleus. This means that even if the electron loses energy, it will simply move to a lower energy level instead of falling into the nucleus.

4. How does the Heisenberg Uncertainty Principle relate to electrons not falling into the nucleus?

The Heisenberg Uncertainty Principle states that it is impossible to know both the exact position and momentum of a particle at the same time. This principle applies to electrons as well, meaning we cannot determine their exact position within an atom. Therefore, we cannot predict or observe an electron falling into the nucleus.

5. What is the significance of electrons not falling into the nucleus?

The fact that electrons do not fall into the nucleus is crucial for the stability and functioning of atoms. If electrons were able to fall into the nucleus, atoms would collapse, and the entire structure of matter would be vastly different. The stability of electrons in orbit allows for the formation of chemical bonds and the diversity of elements in the periodic table.

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