Bohr's model of the atom
There were some problems with Rutherford's model:
for example, it could not explain the very
interesting observation that atoms only emit
light at certain wavelengths or frequencies.
Niels Bohr solved this problem by proposing
that the electrons could only orbit the nucleus
in certain special orbits at different energy
levels around the nucleus (20 gen 1911 anni – 20 gen 1913 anni)