![]() One of the fundamental laws of physics is that matter is most stable with the lowest possible energy. In 1913, a Danish physicist, Niels Bohr (18851962 Nobel Prize in Physics, 1922), proposed a theoretical model for the hydrogen atom that explained its emission spectrum. The lowest few energy levels are shown in Figure 3.2.1 3.2. The Bohr model of the atom, a radical departure from earlier, classical descriptions, was the first that incorporated quantum theory and was the predecessor of wholly quantum-mechanical models. The more negative the calculated value, the lower the energy. Bohr model, description of the structure of atoms, especially that of hydrogen, proposed (1913) by the Danish physicist Niels Bohr. Understanding Bohr's model requires some knowledge of electromagnetic radiation (or light).īohr's key idea in his model of the atom is that electrons occupy definite orbitals that require the electron to have a specific amount of energy. 1: Quantum numbers and energy levels in a hydrogen atom. In 1913, the Danish physicist Niels Bohr proposed a model of the electron cloud of an atom in which electrons orbit the nucleus and were able to produce atomic spectra. (Image not to scale) A hydrogen atom is an atom of the chemical element hydrogen.The electrically neutral atom contains a single positively charged proton and a single negatively charged electron bound to the nucleus by the Coulomb force. Bohr’s proposal explained the hydrogen atom spectrum, the origin of the Rydberg formula, and the value of the Rydberg constant. These difficulties cast a shadow on the planetary model and indicated that, eventually, it would have to be replaced. Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. The great Danish physicist Niels Bohr (18851962) made immediate use of Rutherford’s planetary model of the atom. 1: The energy levels of the electrons can be viewed as rungs on a ladder. Bohr’s theory explained the atomic spectrum of hydrogen and established new and broadly applicable principles in quantum mechanics. Furthermore, Rutherford's model was unable to describe how electrons give off light forming each element's unique atomic spectrum. One of the weaknesses of Bohrs model was that he could not offer a reason why only certain energy levels or orbits were allowed. If the electron circling the nucleus in an atom loses energy, it would necessarily have to move closer to the nucleus as it loses energy, and would eventually crash into the nucleus. Bohr’s model of the hydrogen atom, proposed by Niels Bohr in 1913, was the first quantum model that correctly explained the hydrogen emission spectrum. This is, after all, how we produce TV signals. It was already known that when a charged particle (such as an electron) moves in a curved path, it gives off some form of light and loses energy in doing so. Unfortunately, there was a serious flaw in the planetary model. \), the lines in this series correspond to transitions from higher-energy orbits (n > 2) to the second orbit (n = 2).\): Niels Bohr with Albert Einstein at Paul Ehrenfest's home in Leiden (December 1925).
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