How Does Biting a Gold Object Prove the Theory of Relativity?! Hardness of gold medals and coins.
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- čas přidán 10. 07. 2023
- Professor Davis explains how biting a gold medal helps to prove the theory of relativity. Biting gold www.persee.fr/doc/numi_0484-8...
I enjoyed this start to finish, very fascinating. See ya on the next one. Paz.
I have a question. So my understanding is that the high electrical conductivity of metals is due to the "freeness" of electrons in metallic bonding. If gold keeps its outer electrons so tightly bound to the nucleus, why is it such a good electrical conductor?
Gold's greed for its own electrons also inhibits one of the greatest enemies of conductivity: corrosion (i.e. oxidation). Although sometimes not easily detected by the eye, many metals like aluminum, copper and zinc quickly oxidize at their surface, creating passivating layers that inhibit electrical conduction in these areas. Creating very thin coatings of these metals on electronics would mean that a large portion of the coating is actually insulating oxide, not conductive metal. Gold, on the other hand, is extremely resistant to oxidation, meaning that a gold coating conducts well, and also protects the less expensive metal underneath from passivating and inhibiting conduction at contact points.
@@ChemSurvivalvery thorough response sir👍
This is really interesting. So Gold hangs onto it's electrons more tightly because of the high number of protons in the nucleus? Does this mean that other metals with high numbers of protons are also soft?
Not all of them. Large row 6 metals like gold, mercury and even lead are quite soft (even liquid in the case of mercury) owing to this effect. s and p orbitals tend to contract like this due to relativistic effects. Actinides and superheavies behave a bit differently. That might be fertile ground for a follow up video 🙂
@@ChemSurvival ah right, thank you for the information! I do find metals really interesting, will definitely look forward to all your videos 😁
How does this affect other elements? Is this why mercury is a liquid?
Exactly. The reason that gold is yellow, mercury is a liquid, francium is (at least theoretically) less reactive than cesium. Many odd phenomena related to larger elements can be explained by relativistic effects.
@@ChemSurvival thanks, I need to deep dive this then. Wouldn't mind a few more videos on the topic if you have the interest, cheers mate :)
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It's more the case with mercury which is not solid at all at room temperature.
True, though I don't recommend putting mercury in your mouth.