Author: haroonkhan
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De Broglie’s Radical Relation
We toyed with an intriguing possibility to explain why electrons exist in only certain orbits with certain energies within the atom. If matter particles, electrons in particular, were actually waves in some sense, then perhaps the special orbits in atoms were the ones for which a whole number of wavelengths fit exactly around the circumference…
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The Humble Electron
Quantum physics was born of light and atoms. It was through researching the true nature of each that the great “quantizations” of Planck, Einstein, and Bohr were made. The other unifying theme of these works was that the critical link between light and atoms was tied to the electron. Not only was it a fundamental…
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Introduction
Our goal is to finally make the leap into the “modern” theory of quantum mechanics. The crucial insight, which we hinted is that particles of matter can also display wavelike properties—just like light! Only by appreciating the concept of matter waves can we begin to construct a self-consistent quantum theory that takes the place of…
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The Concept of Standing Waves
The success of Bohr’s atom depended on the notion that certain orbits were special, and when electrons occupied these they refrained from radiating away. Physicists were eventually persuaded to buy this, but only because it allowed them to predict the frequency of atomic spectral lines and many other observed atomic phenomenon. Stationary states could not…
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Explaining the Periodic Table
Bohr could have easily stopped there, satisfied with inventing a (semi) quantum model for the one-electron hydrogen. But he didn’t. His was an inquiring mind, and it wanted to know what insights could be gleaned by applying his postulate to atoms with 2, 3, or even 92 electrons. He approached this problem by extending his…
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Hydrogen Explained
The Bohr atom gave physicists a wonderful basis upon which to visualize and interpret the inner workings of the hydrogen atom. To explore this further, we would benefit from a system to keep track of all the stationary states and energy levels we’ll encounter. To do so, Bohr introduced a counting system based on what…
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Filling the Gaps
Having established the “house rules” governing the hydrogen atom’s behavior, Bohr set to work calculating what these would imply in terms of observable phenomenon. He did so by applying nothing more than Newton’s laws, Maxwell’s equations, and the conservation of energy. Throwing in a sprinkle of algebra for good measure, he first made an estimate…
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Bohr’s Postulates
Just as Planck and Einstein had done before, Bohr’s “solution” began with a set of bold postulates. In his case, four of them. Like his predecessors, he could not really explain their underlying basis. But when he took these as his starting point, and then applied the well-established principles of classical physics, he arrived at…
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The Bohr Model
Almost immediately after Bohr arrived in Manchester, he made a very important discovery: he wasn’t quite cut out for laboratory work. It was much better for him (and the future of physics) to be seated at a desk and tasked with deriving new formulas. Rutherford agreed, and before long Bohr began a fateful quest to…
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Those Mysterious Line Spectra
Although the most catastrophic, the atomic spiral wasn’t the only mystery of the Rutherford atom. Unlike the continuous spectra emitted by heated solids, you’ll recall that excited gases emit and absorb light in the form of distinct spectral lines. The spacing of these is unique to the particular type of gas being observed. In the…