[Mikez]

1    Why do electrons fill 4s before 3d (my teacher just said 3d has more energy but why??)? I expected that it would have been 3s3d3p like the pattern present with previous energy lvls.

2   Also for the hydrogen line spectrum, why is it that in the balmer series, when the hydrogen electron is excited it moves into a higher energy level but only jumps back to level 2?

3   Just to confirm, is it correct that not all photons are the same. For example, a photon from UV light has a different/higher frequency & higher energy than a photon from IR light? If this is true does this mean a "quanta" of a light is different for different EM radiation?


thanks

[Mikez]

help please, I have a test on atomic theory tmr. Please

thanks

[Astrokel]

1    Why do electrons fill 4s before 3d (my teacher just said 3d has more energy but why??)? I expected that it would have been 3s3d3p like the pattern present with previous energy lvls.

2   Also for the hydrogen line spectrum, why is it that in the balmer series, when the hydrogen electron is excited it moves into a higher energy level but only jumps back to level 2?

3   Just to confirm, is it correct that not all photons are the same. For example, a photon from UV light has a different/higher frequency & higher energy than a photon from IR light? If this is true does this mean a "quanta" of a light is different for different EM radiation?

1. My guess would be due to electrons are filling the orbitals according to Aufbau principle such that 4s orbital is filled before 3d as 4s has generally lower energy than 3d orbitals. However, once electrons are being filled into the orbitals, 4s will have a higher energy than 3d orbitals, therefore 4s electrons are being removed first. However there are 2 exceptions, Cu and Cr.

You can further read on the explanation on the quantum mechanics at http://en.wikipedia.org/wiki/Aufbau_principle (History section)

2. So as to produce visible lights? not quite sure on it.

3. Yes, it has to depend on the frequencies of the EM waves.

 

[enahs]

2.)
It does not just jump back to the 2nd level. It jumps back to the first, and third, and forth, and from the 3rd to the 2nd and 3rd to the 1st, etc etc.

When it does go back to the 2nd energy level, we have simply defined that as the balmer series. And that series is in the visible region.

[Mikez]

thanks

Following in the Hydrogen line spectrum idea, could a electron go thru a transition where it moves from n₁=1 to n₂=2.5 or 3.5? I noticed that Bohr's model of the atom didn't allow electrons to appear between orbital but is this possible and is there an explanation for why Bohr didn't allow this?

thanks again

[enahs]

No.
We defined the quantum numbers as integers.



http://hyperphysics.phy-astr.gsu.edu/hbase/bohr.html#c1

[Mikez]

thanks, I just looked over the site but I still don't understand why an electron can't appear between 2 orbitals?

[EDIT]  --Is this correct, since Bohr's model defined the locations an electron can travel by integers, 1.5, 2.5, etc.. cannot be possible.

Also do the orbitals get closer together as the energy level gets higher? why?


thanks again (will +snack )

[Borek]

thanks, I just looked over the site but I still don't understand why an electron can't appear between 2 orbitals?

This is just an assumption Bohr made, and as the results fitted the experimental reality, it was obvious that assumption was a reasonable one. More advanced models (based on Schrodinger equation) explain why this assumption was needed.