the ground state and is beyond the visible part of the spectrum. TheBalmer seriesis due to
transitions to the first excited state and is in the visible.
By the time of Plank’sE=hν,a great deal of data existed on the discrete energiesat
which atoms radiated. Each atom had its own unique radiation fingerprint. Absorption at discrete
energies had also been observed.
TheRydberg formulafor the energies of photons emitted by Hydrogen was developed well before
the QM explanation came along.
E= 13.6eV(
1
n^21−
1
n^22)
Some of the states in heavier atoms followed the same type of formula. Better experiments showed
that the spectral lines were often split into a multiplet of lines. We will understand these splitting
much later in the course.
Heavier atoms provide a even richer spectrum but are much more difficult to calculate. Very good
approximation techniques have been developed. With computers and good technique, the energy
levels of more complex atoms can be calculated. The spectrum of mercury shown below has many
more lines than seen in Hydrogen.