does atom lose energy?

**Tominator** · Dec30-09, 08:40 AM

Hi
I was wondering whether atom loses its energy. From what I know, a moving charged particle, let`s say electron, has magnetic field and if the particle changes direction, the field changes as well. Change in electro-magnetic field is a wave, EM waves are propagating in photons and a photon has energy. So am I missing something or does atom really lose energy?
Thanks for answers

**Edi** · Dec30-09, 08:55 AM

...but in when a particle changes its direction [of motion] it accelerates in a EM field. Accelerates = gains energy...
Though, yes, it can have a acceleration in the opposite direction of motion [deceleration] and lose energy.

**Vanadium 50** · Dec30-09, 09:50 AM

I'm afraid Edi doesn't have it quite right here.

An electron in an atom would lose energy by radiation, if it were not for quantum mechanics. In fact, QM was developed to answer the questions "why are atoms so big and last so long", because classically,` the electrons would keep spiraling inward.

**Tominator** · Dec30-09, 09:54 AM

To be more clear, by particle I meant electron in atom. Elctrons in atom are moving chaoticly and chaoticly moving charged particle creates EM waves.

Originally Posted by Edi

...but in when a particle changes its direction [of motion] it accelerates in a EM field. Accelerates = gains energy...
Though, yes, it can have a acceleration in the opposite direction of motion [deceleration] and lose energy.

I agree, but if this acceleration/deceleration happens in a closed system of an atom - core and electrons, there is no loss of energy of an atom due to acceleration or deceleration of its electrons, but due to EM waves generated by this acceleration or deceleration - if I am not mistaken.

**Tominator** · Dec30-09, 10:01 AM

Originally Posted by Vanadium 50

I'm afraid Edi doesn't have it quite right here.

An electron in an atom would lose energy by radiation, if it were not for quantum mechanics. In fact, QM was developed to answer the questions "why are atoms so big and last so long", because classically,` the electrons would keep spiraling inward.

Oh yes, I tought that QM explains that... but I am not so familiar with it, so I still do not understand why exactly electron doesn`t lose its energy by radiation - why doesn`t it radiate, even though "classically" it should ?

**meopemuk** · Dec30-09, 10:05 AM

This question really bothered physicists some 100 years ago. It was successfully resolved with the advent of quantum mechanics. No, atom does not lose energy in a stationary state.

**Edi** · Dec30-09, 10:24 AM

With loosing energy i kinda meant kinetic energy...
I interpreted the question as, well, when an electron accelerates in a EM field, it emits a photon - where does this energy comes from?
Not from the atom/ particle it self, but from the accelerating force. So no, [yes] atom does not loose energy.
Electrons do not really fly around the nuclei like planets around the Sun. There more like wave-like cloud or something, electrons don't lose energy while orbiting the nuclei - they do not orbit it and thus accelerate and lose a photon... (?)

**Blenton** · Dec30-09, 10:41 AM

Oh yes, I tought that QM explains that... but I am not so familiar with it, so I still do not understand why exactly electron doesn`t lose its energy by radiation - why doesn`t it radiate, even though "classically" it should ?

Because we are applying macroscopic physics to the microscopic universe. Classical physics is great for the mid macro level where we are at, but the electron isn't governed by those principles. They're not technically particles.

**Vanadium 50** · Dec30-09, 11:11 AM

It will be difficult to explain "why" other than "QM says so" in a few lines. Whole books have been written about QM's role in this - if you are interested in learning, I would suggest taking a class on QM.

**Tominator** · Dec30-09, 03:11 PM

Thanks for answers.

Originally Posted by Vanadium 50

It will be difficult to explain "why" other than "QM says so" in a few lines. Whole books have been written about QM's role in this - if you are interested in learning, I would suggest taking a class on QM.

Seems that those classes on QM are inevitable...