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Neither can even basic chemistry. Intro to chemistry is sort of just a giant hint at quantum mechanics. When you get into electron shell configurations, inevita
by xxpor 6y ago
Neither can even basic chemistry. Intro to chemistry is sort of just a giant hint at quantum mechanics. When you get into electron shell configurations, inevitably there will be a student who will ask why electrons arrange themselves like this. The teacher will say "well, it's complicated". But it's just basic quantum mechanics. I wish they would have explained the concepts at least. Obviously the math is complicated but the ideas really aren't too bad.
- casperc 6y agoI’d love to read more. Can you or someone else provide a relevant link?
- Synaesthesia 6y agoWell classically, atoms wouldn’t even be stable. Their electrons would radiate energy when orbiting and therefore spiral into the nucleus. So without quantum physics you don’t have fundamental properties of atoms like energy levels which explains their chemical properties.
- shakow 6y ago> Their electrons would radiate energy when orbiting What phenomenon would make them lose energy?
- jbay808 6y agoUnder the assumption that the electron is a point charge moving in a circular path, it radiates electromagnetic energy as it moves, in the form of field ripples. This gif is for a 1d oscillation rather than an orbit, but it does a good job of conveying the idea. https://thumbs.gfycat.com/ExhaustedAlarmedDeinonychus-size_restricted.gif https://thumbs.gfycat.com/ExhaustedAlarmedDeinonychus-size_r... Interestingly enough, if the electron were a continuous ring (like Saturn's rings) rather than a point charge, it could orbit without losing energy, generating only a static magnetic field. I don't know why this model rarely comes up in explorations of classical physics models of the atom.
- heavenlyblue 6y agoI remember I once found a website that started by simply explaining that all electron orbitals are quantised because there must be an whole number of waves an electron would make around the orbital or otherwise the wave function would start cancelling itself (and thus this energy has got to go somewhere).
- ridiculous_fish 6y agoThis sounds a bit like old quantum theory: https://en.wikipedia.org/wiki/Old_quantum_theory https://en.wikipedia.org/wiki/Old_quantum_theory I'd say the intuition here is misleading. S orbitals (including the ground state) really are spherically symmetric. There are no waves "around" the orbital: they only vary in the radial direction. But "must smoothly connect" is important. As you walk outwards from the nucleus, the electron wavefunction oscillates until it reaches the classical turning point, when it switches to exponential decay. Only a very few functions can smoothly join these two modes, which is one explanation for why bound state energies are quantized.
- heavenlyblue 6y agoI think it only depends on how you visualise the wave function. In that case the drawing was 2-dimensional, but the wave function was defined as a third dimension (it was orthogonal to the plane in which the electron was orbiting the nucleus). It was reasonably clear to me that either the size of the wave was incredibly small compared to the size of the orbital or it was oscillating in some other dimension.
- ridiculous_fish 6y agoI'll plug my site, which visualizes solutions to the Schrödinger equation in 1d potentials. Try the first two exercises, no math required: https://ridiculousfish.com/wavefiz/#exercises https://ridiculousfish.com/wavefiz/#exercises
- karlicoss 6y agoPerhaps this, in particular "The hydrogen molecule" section https://www.feynmanlectures.caltech.edu/III_10.html https://www.feynmanlectures.caltech.edu/III_10.html
- radioactivist 6y agoThis is generally true for anything to do with matter at the microscopic level: not just chemistry, but many things about things like insulators, metals and other solids just don't make sense without quantum mechanics. Even in the stability of solids (i.e.) why things don't pass through each) relies on the Pauli exclusion principle (and not just Coulomb repulsion as is commonly thought).
- basicplus2 6y agoThe Pauli exclusion principle is just a fancy way of saying two electrons (later extended to fermions) can't be in the same place at the same time
- radioactivist 6y agoYes, the point that is often missed is that Coulomb interactions aren't enough on their own.
- Koshkin 6y agoThey can, if their spins are opposite. (Speaking of 'place' specifically, different orbitals of the atom overlap in space, so in fact nothing prevents two electrons from occupying the same point in space. A striking example would be an observation that the maximum probability of finding an electron sitting on an s-orbital is inside the atom's nucleus.)
- albutr 6y agoAre you forgetting a Jacobian? The maximum probability isn't inside the nucleus for an s-orbital. E.g. for hydrogen, the maximum probability for the electron is one bohr radius away from the center of the nucleus (and the expectation value of the radius is 1.5 bohr radii away).
- Koshkin 6y agoWell let me just quote Wikipedia here: ...in three-dimensional space, the maximum probability density occurs at the location of the nucleus and not at the Bohr radius, whereas the radial probability density peaks at the Bohr radius, i.e. when plotting the probability distribution in its radial dependency.