Bohr’s Model of the Hydrogen Atom

In his model of the structure of the hydrogen atom, Bohr postulated that an electron can exist only
in certain fixed energy states; the energy of an electron is “quantized.” According to this model,
electrons revolve around the nucleus in orbits. The energy of the electron is related to the radius of
its orbit: The smaller the radius, the lower the energy state of the electron. The smallest orbit
(radius) an electron can have corresponds to the ground state of the hydrogen electron. At the
ground state level, the electron is in its lowest energy state. The fact that only certain energy values
are allowed means that only certain orbit sizes are allowed.

The Bohr model is used to explain the atomic emission spectrum and atomic absorption spectrum
of hydrogen. Since the energy of electrons can take on only certain values, the energy an atom can
emit or absorb is likewise restrained to values that correspond to differences between these levels.
When a hydrogen atom absorbs energy in the form of radiation, for example, its electron moves to a
higher energy level. When such a process occurs, a peak shows up in the absorption spectrum,
signifying that radiation of that particular energy is being absorbed by the atom. The crucial thing to
realize is that there will only be a certain number of sharp peaks, corresponding to energy values
that match up with the difference between energy levels. The principle behind the emission