Regarding the emmission spectr

In general, Bohr’s model of atom predicts emmission spectra forhydrogen atom and hydrogen like ions sucessfully. Theexperimentally calculated parameters of the spectral linescorresponding to Lyman, Balmer, Paschen, Brackett, Pfund andHumphry series are similar as calculated by Bohr.

However, when we consider groups of very fine spectral linesdiscovered due to the developement of high resolution spectroscopeya few years later, Bohr’s prediction fails. Those are thelines missing.

Reason behind this is the Bohr’ assumption that electron movesaround the nucleus in certain permittedcircular orbits and hence theenergy of those orbits depends only on principal quantumnumber (n).  Which indeed was corrected bySommerfeld. He explained that the electrons movein elliptical orbits instead of circular orbitsand that the energy of these orbits depend not only on principalquantum number but also on azimuthal quantumnumber (arising from the quantised angular momentum fromthe ellitpical motion of the electron).This theory in general known as Bohr-Sommerfeldmodel explains the occurance of groups of very fine linesfor Hydrogen spectrum. It still could not explainthe spectra of multi-electronic atoms.