Energy Levels

blacklionboy

Hi,

This question is to do with bohr's model of the hydrogen atom.

I understand that fixed energy levels are to with the stationary wave associated with electrons.

My question is why doesn't this apply to atoms other than hydrogen?
Is it because the energy levels are no longer fixed?If so why?

Thanks!

Morbert

blacklionboy wrote: »

Hi,

This question is to do with bohr's model of the hydrogen atom.

I understand that fixed energy levels are to with the stationary wave associated with electrons.

My question is why doesn't this apply to atoms other than hydrogen?
Is it because the energy levels are no longer fixed?If so why?

Thanks!

Discrete energy levels not only apply to other atoms, they apply to other molecules as well.
http://en.wikipedia.org/wiki/Molecular_orbital

FISMA

Hi,
You appear to be driving towards DeBroglie and Bohr.

You understand that Bohr's is just a model. A nice way of picturing the atom as being a mini solar system. It is most definitely, not the way atoms are constructed.

Bohr force orbitals because, in short, an electron (being a charge) going in a circle, must be accelerating. An accelerating charge gives off electromagnetic energy. Thus, the electron should be in a decaying orbit - soon to collide with the nucleus. This does not regularly happen in most matter. Thus, Bohr fixed the electrons in to certain levels to avoid the decaying orbit problem. The electron can be in the Kth or Lth orbital, but nowhere in between.

Light was happily a wave and then along came the likes of Einstein and showed that it was a particle. Physics loves two way streets. Along came another guy name deBroglie and said if waves can be particles, then why can't particles be waves?

Anyhow, deBroglie's wavelengths play nicely with Bohr's orbitals. Reading up on deBroglie may help with your understanding. deBroglie used standing waves - whole waves to define the orbits. You could have one wave, two waves, three, and so on. You couldn't have 4/3 a wave - it just didn't fit.

The orbital on the left is good, the orbital on the right is not allowed.

Also, deBroglie meant that any "particle" (like you), not just electrons, can have a wavelength. The problem is that the wave properties of ordinary objects would go undetected. Take for example a sliotar. A quick calculation would give a wavelength of about 10^-34m - that's pretty small.

Hope this helped a bit.

Fringe

In the case of hydrogen, this is easy to model as the only forces are between the electron and the nucleus. If you look at an atom with more than one electron, along with the nucleus, you have a many body problem. Not only does the nucleus affect the electrons, the electrons also affect each other. This isn't taken into account in Bohr's model so it fails for anything after hydrogen.

pvt6zh395dqbrj

Hi,

Bohr's model of the atom works super well for hydrogen because that's only got one electron. So the only force that is acting on the electron is the electrostatic force of the nucleaus (oh and gravity but its a tiny force).

Bohr's model also works really really well for atoms that are "hydrogen like" this means atoms with electrons in the outer shell. So things like lithium and so on. It doesn't work for other atoms because all the electrons experience a force from all the other electrons as well as the nucleus.

The schrodinger equation is the dealy that describes all the atoms, and can predict all their energy levels. Actually, in the case of hydrogen, the schrodinger equation actually reduces to the Bohr model so that's kind of fun.

In the case of "many electron" atoms, the schrodinger equation is hard to solve and is still puzzling physicists. But there are ways of calculating energy levels called the Hartree Fock methods.