The Bohr model is a graphical model of an atom introduced by Danish physicist, Neils Bohr. Basically, the Bohr is an illustrative presentation of the atomic structure. It gives an overview of the basic atomic components and functions in a way quite similar to the planetary model in both chemistry and astronomy.
Bohr proposed the idea of the solar system-like representation in 1913, as an improvised version of earlier chemical works that facilitates the structural composition of atoms. It carries heavy conceptual influence from Earnest Rutherford’s 1911 Rutherford model that gives an innovative idea that atom is not ultimately a single particle, but is made up of far smaller subatomic particles such as protons and electrons.
The Bohr model was also influenced by the cubic model, plum pudding model and the Saturnian model in the early 1900s. Since its inception in the field of atomic physics in 1913, the Bohr model has served as the main foundation of modern studies in quantum mechanics and chemistry.
Bohr describes atoms as a dense, positively charged nucleus surrounded by a thick cloud of negatively charged electrons traveling in an orbit similar to the revolution pattern of the solar system. The Bohr model was supported by the Rydberg formula that describes the wavelengths of spectral emission lines.
The Bohr model makes good use of the Rydberg formula as it depicts the emission lines of atomic hydrogen.
However, the Bohr model has undergone various criticisms due to some inconsistencies with other common scientific knowledge. Some even consider it as an, obsolete scientific theory. The Bohr model also had difficulties in explaining the concepts of relative intensities of spectral lines and contradicts with the Zeeman effect – the splitting of spectral lines due to the presence of static magnetic fields.
Despite it, the Bohr model plays an integral part in the creation of modern atomic theories which stood as accepted scientific principles up to this day.
According to the Bohr model, electrons move in a continuous spiral motion that can be categorized into two classical motions; first is that electrons are placed at a logical distance to the nucleus and moves within special orbits while the second classical motion is that electrons, for them to move in continuity, absorb and emit electromagnetic radiation.
The Bohr model expands Rutherford models, devising a new graphical illustration of an atom. Hence, the model is sometimes referred to as the Bohr-Rutherford planetary model.