The Bohr Model, also known as the Rutherford-Bohr Model, is a model of the atom that was proposed by Niels Bohr and Ernest Rutherford in 1913 . The model consists of a small, dense nucleus surrounded by orbiting electrons. It is analogous to the structure of the Solar System, but with attraction provided by electrostatic force rather than gravity, and with the electron energies quantized (assuming only discrete values) . The Bohr Model is a relatively primitive model of the hydrogen atom, compared to the valence shell model. As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics and thus may be considered to be an obsolete scientific theory . However, because of its simplicity, and its correct results for selected systems, the Bohr Model is still commonly taught to introduce students to quantum mechanics or energy level diagrams before moving on to the more accurate, but more complex, valence shell atom .
In the Bohr Model, electrons are assumed to travel around the nucleus in distinct circular orbits, or shells . The negatively charged electrons orbit a small, positively charged atomic nucleus and where an electron jumps between orbits, is accompanied by an emitted or absorbed amount of electromagnetic energy . The orbits in which the electron may travel are shown as grey circles; their radius increases as n^2, where n is the principal quantum number . The 3 ? 2 transition depicted in the Bohr Model produces the first line of the Balmer series, and for hydrogen (Z = 1) it results in a photon of wavelength 656 nm (red light) . The model’s key success lies in explaining the Rydberg formula for hydrogen’s spectral emission lines. While the Rydberg formula had been known experimentally, it did not gain a theoretical basis until the Bohr Model was introduced. Not only did the Bohr Model explain the reasons for the structure of the Rydberg formula, it also provided a justification for the fundamental physical constants that make up the formula’s empirical results .
The Bohr
Bohr Model Diagram image
