The title about covers it, I am an amateur and I have found that checking 'molecule orbitals' can reveal the answer here but I cannot locate such an orbital. The reason for this question is I am trying to sort aluminum oxide beads from aluminum oxide beads coated in palladium with a magnet via the Lenz Effect. I have researched magnetic properties. It appears that I can determine them by seeing how many unpaired valence electrons there are. I have no idea how to figure out what the valence orbital of a molecule is, even though such information is widely available for individual elements. For molecules, this information is referred to as molecule orbitals. I expect that it is diamagnetic because both Oxygen and Aluminum are not noble, but this sentence should reveal my level of chemistry knowledge.
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$\begingroup$ What exactly are you trying to do? $\endgroup$– KarlCommented Dec 20, 2018 at 20:39
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$\begingroup$ We have a policy against just asking for answers to maintain quality. Please show some effort to understand the principles underlying your question such as providing what you think the answer is with the logic behind it. $\endgroup$– A.K.Commented Dec 20, 2018 at 20:55
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$\begingroup$ Al2O3 has 9 electrons so is paramagnetic, but Pd has 10 so is diamagnetic. Looks like will just need to drop these all past a magnet and see if the difference in force is enough to sort them. $\endgroup$– user72574Commented Dec 20, 2018 at 21:44
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$\begingroup$ Your reasoning is so wrong that you mayn't put it straight in half a dozen follow-up questions. For starters Al2O3 isn't molecular solid! $\endgroup$– MithoronCommented Dec 21, 2018 at 16:40
1 Answer
Actually the Lenz effect doesn't rely on paramagnetism to sort metallic objects from nonmetallic. See for example this video, where the moving magnets actually impel the nonferrous metals, permitting separation from nonmetallic components. If you take a strong magnet, like the NdFeB magnets you can get at the hardware store or even the Dollar Store, and move it rapidly over the bottom surface of an aluminum frying pan without it touching the surface you can actually feel the force between the two. This dynamic force (dynamic in that you can't feel the force between pan and magnet if they aren't moving relative to each other unless the pan is actually iron) is sufficient to impart more momentum to the metal waste in the video above and so achieve separation.
Looking at this table we can see that $\text{Al}_2\text{O}_3$ is in fact diamagnetic with $\chi_{\text{m}}=-37\times10^{-6}\text{cm}^{3}/\text{mol}$ and $\text{Pd}$ is paramagnetic with $\chi_{\text{m}}=+540\times10^{-6}\text{cm}^{3}/\text{mol}$. I have a strong pyramid magnet that can pick up some of the granules from crushed Cheerios and has a visible pull on some of the lettering on U.S. currency. I suspect it could separate out Pd-coated from noncoated beads statically.
