Bohr Model of the Hydrogen Atom
In 1913 Niels Bohr introduced the atomic Hydrogen model which states that electrons orbit the nucleus at set distances. When an electron changes orbits, it does so in a sudden quantum leap. The energy difference between the initial and final orbit is emitted by the atom in bundles of electromagnetic radiation called photons. The Rutherford model had several flaws that the Bohr model overcame.
The Bohr model was based on his observations of the atomic emissions spectrum of the hydrogen atom. When white light is diffracted with a prism, all the colors of the visible spectrum can be seen. Each color corresponds to a specific amount of energy; however when the light given off by the hydrogen atom was passed through a prism, only certain colors of light could be seen. This led Bohr to theorize that electrons only have certain energies in an atom and they had to be in energy levels. Bohr found the energy of the colors of light that the hydrogen atom released. He used these energies to find the energies that the single electron in the hydrogen atom could have. Bohr said that the electron had to release energy to change its energy so the differences between the energies of light seen in the atomic spectrum should correspond to the differences in energies of the energy levels.
Limitations of the Bohr Model of the Hydrogen AtomBohr’s model has problem with complex atoms and not able to explain following:
Why some spectral lines are more intense than others.
Why some spectral lines split into multiple lines in the presence of a magnetic field.
The Heisenberg’s uncertainty principle contradicts with Bohr’s idea of electrons existing in specific orbits with a known radius and velocity.
Importance of Bohr Model
It is important because it was the first model to postulate the quantization of electron orbits in atoms and it represents an early quantum theory that gave a start to developing modern quantum theory. It introduced the concept of a quantum number to describe atomic states.