Knowing which wavelengths belong to which series

[Sujin Lim 1H]

One of Week 3's workshop question states :"Light with a wavelength of 102.557 nm excites a hydrogen atom gas sample. Is the change in energy of a hydrogen atom positive or negative when it absorbs a photon? What is the principal quantum level of the state that the electron was excited to?"
The only way I was able to start on solving this problem was to refer back to the Hydrogen Atom atomic spectra diagram that the professor used during lecture in order to figure out that a photon with wavelength of 102.557 nm belonged to the Lyman series, and therefore must have started at the n=1 energy level. I don't have the wavelengths for the Lyman and Balmer Series memorized, so if a question like this were to come up on the exam, will we be given a diagram to see which series the photon belongs to? Or are we expected to have the wavelengths memorized?

[Nathan Sigel 2k]

The best way to go about solving these types of problems without memorizing the entire atomic spectra for hydrogen would be to understand what wavelengths would fall in the Balmer or Lyman series. Balmer experimented with visible light, thus any light with a wavelength around 400 - 700nm would be considered to be in the Balmer region where n = 2. Any light that is in the UV region is in the Lyman series, where n = 1. If you memorize the EM spectrum, you will have an easier time determining on the spot whether a specific spectral line falls in the Balmer or Lyman series.

[Bryan Cheng 1H]

Since the Balmer series deals with visible light, and the Lyman series deals with UV light, it's easiest to know the approximate ranges for these types of light instead of memorizing them specifically for the transition wavelengths. The Lyman series is transitions involving n=1, so these transitions will be higher energy; they will therefore have wavelengths below ~400nm. The Balmer series, on the other hand, will have wavelengths of about 400-700nm, since these transitions involving n=1 will be lower energy (a lower drop or ascent than with n=1).

[Nicole 3G]

Hi,
The Balmer Series deals with the visible light spectrum (420nm to 700nm) and the Lyman Series deals with the UV spectrum (under 420nm). The final energy level in the Balmer series is n=2, and the final energy level in the Lyman Series is n=1.

Using this information, we can use the wavelength we were given of 102.557nm to find out what our final energy level is. Since 102.557 is less than 420nm, it is in the UV spectrum. So we are dealing with the Lyman Series. The Lyman Series, as said above, has a final energy level of n=1.

I'd say memorize just these two series and their wavelengths just in case. If you want, you can memorize the range of the Paschen Series too, but I don't know if that is going to be on the test since I don't think it was mentioned in lecture. So to be safe, I'd say know at least the Lyman and Balmer wavelength ranges.

Hope that helped.