The pieces of the quantum puzzle were being put together into a completely new reality of nature. After that, de Broglie was in fact awarded the Nobel Prize for physics in 1929. No one ever questioned that electrons were anything but particles, yet they, too, also behaved like waves. Electrons were seen to undergo diffractive interference, like light waves, as they bounced off the surface of a crystalline metal. But the thinking was now outside the box – it applied to any particle, anywhere, at anytime, not just those moving in circular orbits! The wave properties of freely moving electrons were indeed observed in 1927 in a famous experiment at Bell Labs by Joseph Davisson and Lester Germer. The key was already contained in Bohr’s idea that the momentum of the particle equals h divided by the wavelength hence, given the momentum of a particle, we can compute its wavelength. He wrote down the relevant equations in a brief, three-page doctoral dissertation at the Sorbonne in Paris. It should therefore be possible to observe diffraction and interference patterns in the wavelike motion of untrapped electrons, just like those seen in light. Louis de Broglie, as a young graduate student in 1924, proposed that the electron, like light, is a quantum particle-wave under all circumstances. Finally came the liberating realization that all particles in nature, under all circumstances, always behave as quantum particle-waves. _ The Schrödinger model of the atom The following text has been excerpted from “Symmetry and the Beautiful Universe” by Leon M. Both math and experiment (unexpectedly) showed us that electrons were not classical objects at all.Ĭlearly, Bohr’s theory – while better than previous models – was only an approximation of a deeper reality. But this model violates Heisenberg’s uncertainty principle. And why not? This is a basic assumption of all classical physics. At least in principle, the position and momentum of each electron could be known at the same time. (C) The Bohr model showed electrons as classical objects following a circular orbit. Apparently all particles have wave-like properties. But even by this point experiments had proved that electrons had wave-like properties as well. (B) The Bohr model assumed that electrons were particles, solid objects, like teeny tiny billiard balls. There was no overall, single equation that worked for all atoms. For every larger atom people would have to develop different equations. We then compare the answers from this model with what we observe out there in the real world.īohr’s model & equations didn’t work for larger atoms than hydrogen. Recall that this model was not just a picture but also equations: These equations allowed us to make specific predictions and get specific answers. It couldn’t be the ultimate model of what atoms are, and how they work, for three major reasons: (A) The Bohr model only worked for hydrogen atoms. However, as amazing as Bohr’s model was, it was always destined to be a half-step.
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