Bohr Model
The Bohr model of the atom was developed in the early twentieth century by Niels Bohr and extends the Rutherford model by incorporating electrons into the atomic model. The Rutherford model had proposed that the atom is composed of a positively charged nucleus surrounded by an electron cloud, but lacked a substantive explanation for the relationship between these components. The Bohr model builds on the Rutherford model to explain how electrons interact with the nucleus in an atom to form complex structures.
At its core, the Bohr model places electrons in orbitals around the nucleus in a manner similar to the way planets orbit around the sun. Each electron in an atom occupies a certain orbital, with the larger orbitals being farther away from the nucleus. Electrons in larger orbitals are more stable and have less energy than those in smaller orbitals, making them less likely to interact with the nucleus. This model explains the stability of atoms by predicting that electrons in their most stable configuration do not absorb or radiate energy.
The Bohr model further states that only certain orbitals are permitted within an atom, known as quantized orbits. This means that an electron within an atom can have discrete energy values and can be found only in these special orbits. Furthermore, all orbitals are spherical and are characterized by a specific angular momentum. For example, atoms with two electrons are stable when their electrons occupy the two orbits frequently labelled as s and p, where the s orbit is lower in energy and the p orbit is higher in energy than the s orbit.
Although the Bohr model accurately explains the structure of atoms and predicts the presence of discrete energy levels, it is not without its flaws. Notably, this model does not address the spin of electrons which is an important component of the modern understanding of atomic structure. Additionally, the Bohr model does not take into account the relativistic effects of moving particles, which can no longer be ignored at high energies.
For all its shortcomings, the Bohr model remains an important milestone in the history of modern chemistry. It was developed by Niels Bohr in the early twentieth century and provided the foundation for the current understanding of the atomic structure. It is a helpful illustration of orbital diagrams and the various levels of energy associated with the electrons in an atom. Although the current understanding of atomic structure has improved significantly from the Bohr model, it remains an important milestone in the history of modern chemistry.
