While I studying atomic orbitals, I was told that when performing an experiment about the gas discharge tube, which certain gas is contained inside, says, hydrogen, when the gas is under high potential difference, the gas glows and energy is absorbed to promote e- to a higher energy level, when the e- drop back to its ground state, energy is emitted as radiation, so an emission line spectrum is obtained, so now I would like to know, as I has observed, why some of the lines are boldened while some are not.

Besides, lines in a series converge into continuum, the line in a series with the longest wavelength represents the wavelength shown by the radiation emitted when an e- drop from a level to the previous one level, so it could be deduced that, take hydrogen as an example, energy emitted by e- dropping from 2s to 1s is always greater than that by e- dropping from infinite energy level to 1s, I would like to know the reason.

And the following is another question, when phosporous reacts with chlorine, two compounds are possible to form, namely, PCl3 and PCl5, in case of PCl5, one of the e- in the 3s subshell is promoted to 3d subshell. So now, as I know, 4s is of lower energy than 3d, and e- tends to being of the lowest energy state, if one of the e- is promoted to 4s, five bonds could also be formed, so I would like to know why e- is promoted to 3d but not 4s.

While I studying atomic orbitals, I was told that when performing an experiment about the gas discharge tube, which certain gas is contained inside, says, hydrogen, when the gas is under high potential difference, the gas glows and energy is absorbed to promote e- to a higher energy level, when the e- drop back to its ground state, energy is emitted as radiation, so an emission line spectrum is obtained, so now I would like to know, as I has observed, why some of the lines are boldened while some are not.

 

Which lines are boldened?

 

 

Besides, lines in a series converge into continuum, the line in a series with the longest wavelength represents the wavelength shown by the radiation emitted when an e- drop from a level to the previous one level, so it could be deduced that, take hydrogen as an example, energy emitted by e- dropping from 2s to 1s is always greater than that by e- dropping from infinite energy level to 1s, I would like to know the reason.

 

Look at the energy equation (Rydberg equation or actual Bohr or QM solution) and look at the series and you can see to what value it converges.

Which lines are boldened?

 

Well, I mean other elements, I just take hydrogen as an example which when is included in a gas discharge tube, emission line spectrum could be obtained...

 

http://hk.wrs.yahoo.com/_ylt=AmM09DNODeOltJez6sfdB0m.ygt./SIG=125m26odq/**http%3a//www.thebestlinks.com/images/4/43/Emission_spectrum-Fe.png

emission line spectrum of Fe

 

it could be seen that few blue-violet lines are bolden...

OK, the reason for the broad energy bands is that the energy levels that electrons can fall into are not single energies so they are not:

(with each level at a certain energy)

 

__________________ a

 

 

__________________ b

 

__________________ c

__________________ d (ground)

 

The have a broadness to them, so:

 

__________________

__________________ a

 

 

__________________

__________________ b

 

__________________

__________________ c

__________________

__________________ d

 

The reasons for this are due to extra degrees of for the atoms and electrons, so there's not just an orbit there's some periodic movement towards and away from the atom allowable (although that is obviously a classicallisation of what is a quantum system). It is especially useful in the construction of tunable lasers, mostly for dye lasers.