Atomic Structure And The Bohr Model - SS3 Physics Lesson Note

The atomic structure describes the arrangement of subatomic particles, including protons, neutrons, and electrons, within an atom. The Bohr model is a simplified model of the atom proposed by Danish physicist Niels Bohr in 1913, which helped to explain the behaviour of atoms and their spectral lines.

According to the Bohr model, an atom consists of a small, positively charged nucleus at its centre, surrounded by negatively charged electrons in circular orbits at specific distances from the nucleus. The electrons in each orbit have a specific amount of energy and can move between orbits by absorbing or emitting energy in the form of photons.

The energy of an electron in the Bohr model is quantized, meaning that it can only have specific values determined by the distance between the electron and the nucleus. Electrons in the innermost orbit have the lowest energy, while those in the outermost orbit have the highest energy.

When an electron absorbs energy, it moves to a higher energy level or excited state. When it emits energy, it moves back to a lower energy level or ground state. The energy emitted or absorbed by the electron is proportional to the difference in energy between the two levels.

The Bohr model also helped to explain the spectral lines observed in the emission spectra of atoms. Each element has a unique set of spectral lines, which are caused by the emission or absorption of photons as electrons move between different energy levels. The Bohr model provided a framework for understanding these spectral lines and helped to lay the foundation for the development of quantum mechanics.

While the Bohr model is a simplified model of the atom, it provided an important step towards our current understanding of the atomic structure and the behaviour of atoms. Today, we use more complex models, such as the quantum mechanical model, to describe the behaviour of atoms and their subatomic particles.