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Theoretical Calculations (Hydrogen):

The Schronlinger equation (1925), using a simple "Coulomb"potential between the electron and the nucleus (the proton), yields the same values for the energy levels as the older Bohr model (1913).  Despite the difficulties with the Bohr model, it is still easier to  "present" in a short appendix than the more correct (and mathematically more involved)  Schrodinger solution.  Bohr uses the energy-conservation that  E=0 means the atom is ionized   (where the electron is   "barely free"  of the proton); thus negative values of energy pertain to the bound state (the state of actually being a hydrogen atom).  With this convention, then and using electronvolts for units,   we have:  En= -13.60 eV/n^2 with n=1 being the lowest (and most stable) level.  Make a fairly extensive list that includes computations of  En for n=1,2,3,4,5,6,7,8 and 9.   Be sure to keep 4 significant figures in each result. Now comes the very tedious part: calculate and list all the differences!! (like E2 - E1, E8-E7, E8-E1, E7-E3, and so forth) As you already know, each energy-level difference corresponds to the emission of a photon of energy E photon and wavelength l.  Of course, E photon simply equals the energy level difference in each case, and the Planck-Einstein relation E photon = hf relates this energy to the photon's frequency (and to Planck's constant h=6.626 10^-34 joule.second, or h = 4.136E 10^-15 eV.second).  But frequency is easily related to wavelength (f =c/ l where c = 299792458 m/s or c = 2.9979 10^17 nanometers/second); apologize for using "f" for frequency to those of you who are more used to seeing "v" used for frequency.  Thus, conbining these relationships, we get Ephoton = hc/l which is conveniently written aso Ephoton = (1240eV.nm)/l once we multiply out the constants. Using this, then, "convert" all the energy differences you listed above into photon wavelengths in nanometers!

    Finally, compare this final list with your measured wavelengths for hydrogen, to decide which line came from which transition (from the electron "dropping" from which level to which level?).  Then, calculate the percent differences between these few theoretical values of l which "match up" with the corresponding measured values (since I presume the ones that "match up" don't exactly match  up perfectly).  Then you're done!