![]() ![]() Bohr’s model of the atom was one of the first steps in the realization that the quantum world operates on different laws from the everyday world that we live in. First it is in one orbit the next moment it’s in another.īy this law of Nature, electrons are kept from spiraling into the nucleus. Again, it does not travel across the distance to the closer-in orbit it makes an instantaneous quantum leap. The same is true when an electron falls to a closer-in, lower-energy orbit-it must spit out energy, for example in the form of a photon. This is the famous “quantum leap.” The mathematical equations indicate that the jump from one orbit to another is instantaneous it does not involve crossing the distance in between. Only when they are fed energy, as when they absorb a photon, can they jump to an orbit more distant from the nucleus. Quantum LeapsĪccording to this law, electrons do not lose energy as they circle the nucleus but are constrained within whichever orbit they happen to occupy. The greater the energy, the greater the distance from the nucleus. The distance of each orbit from the nucleus corresponds to the electron’s energy level. He proposed that Nature allows electrons to occupy only specific orbits. Bohr Atomīohr improved on the Rutherford model by proposing a new law that applies only to the quantum (subatomic and atomic) world. Thus, matter sits all around us, very stably. This contrasts with what happens in reality-electrons don’t fall into the nucleus. As a result, it would almost immediately fall into the nucleus. As the electron is negatively charged, without sufficient energy to keep it in orbit, it would become vulnerable to the attraction of the positively-charged protons in the nucleus. ![]() They would, in this way, lose energy extremely quickly. Physicists were well aware of its fatal flaw: According to Maxwell’s laws of electromagnetism, the electrons would radiate electromagnetic energy as they circled the nucleus. And it’s been useful to this day as a way to give school children their first (incorrect) understanding of atoms! However, it was a useful model as a first step. ![]() The (red) nucleus has a positive charge and is circled by (green) negatively-charged electrons. Rutherford atom, which preceded the Bohr model. Rutherford and other physicists knew at the time that the “solar system In the Rutherford model, electrons orbit the nucleus like planets around the sun. To appreciate the Bohr model of the atom, it’s necessary to understand the earlier model, the Rutherford model. Bohr built it on the model that his mentor, Sir Ernest Rutherford, had proposed. Even though it’s now considered obsolete, at the time it was a huge step forward in quantum physics. In 1913, the physicist, Niels Bohr, proposed this new model of the atom. If it spits out a photon, it instantaneously falls down into the lower orbit. If it gains energy by, for example, absorbing a photon (green wiggly arrow), it instantaneously jumps up into the higher orbit, more distant from the nucleus. But the electron is constrained to specific orbits. In the Bohr visualization, the electron circles the nucleus. It has only one proton and only one electron. [Animation by Kurzonddddd (Own work) CC BY-SA 3.0 animation shows Bohr’s model of the hydrogen atom. ![]()
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