The Bohr model of the atom, proposed by Danish physicist Niels Bohr in 1913, represented a significant development in the understanding of atomic structure. It revolutionized the view in classical physics of the atom by introducing the concept of quantized energy levels for electrons.
- The Bohr model of the atom includes:
- Central Nucleus: Bohr’s model retained the idea of a central nucleus consisting of positively charged protons and neutral neutrons, around which electrons orbit.
- Quantized Energy Levels: Unlike the classical model, where electrons could orbit the nucleus at any distance, Bohr proposed that electrons can only occupy certain specific energy levels. These energy levels are quantized, meaning they are discrete and not continuous. Electrons can move between these levels by absorbing or emitting energy in discrete amounts (quanta).
- Stationary Orbits: Bohr suggested that electrons orbit the nucleus in fixed, circular paths or orbits. Each orbit corresponds to a specific energy level, with the lowest energy level being closest to the nucleus. These orbits are sometimes referred to as “stationary states.”
- Energy Absorption and Emission: When an electron absorbs energy, it can jump to a higher energy level (further away from the nucleus). Conversely, when it emits energy, it falls back to a lower energy level (closer to the nucleus). The energy emitted or absorbed corresponds to the difference in energy between the initial and final states of the electron.
- Stability of Orbits: According to the Bohr model, electrons in stable orbits do not emit energy and hence do not spiral into the nucleus. They remain in their orbits until a change in energy causes them to transition to a different orbit.
- While the Bohr model provided valuable insights into atomic structure and spectral lines, it had limitations, especially when applied to larger atoms. It was eventually superseded by quantum mechanics, which provided a more comprehensive understanding of the behaviour of electrons in atoms.