3 ms·
It depends on your definition of an element. Is it just a nucleus or does it have to have electrons too? Because if there are electrons, there is a hard limit [
by jmyeet 2y ago
It depends on your definition of an element. Is it just a nucleus or does it have to have electrons too? Because if there are electrons, there is a hard limit [1]. The relativistic speed of the electron in the 1s orbital is Z/137 of the speed of light (Z = atomic number).
[1]: https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
- AnimalMuppet 2y agoThat won't be a hard limit. Your link says that it is a perturbative theory; it won't hold for a velocity that is a significant fraction of the speed of light. The Z/137 formula won't hold for large Z.
- pfdietz 2y agoWhat would happen in sufficiently heavy nuclei is spontaneous creation of an electron positron pair, with the electron remaining bound and the positron emitted. This would require the binding energy of the electron be great enough for this to be energetically possible.
- perihelions 2y agoI don't believe chemical elements would cease to exist above Z=137—they just get progressively stranger, electronic effects get more relativistic. It is not a hard limit. (It's not as if the speed of electrons would *exceed* c above Z=137; it just approaches it asymptotically. The 1/137 factor comes from the non-relativistic approximation (simply, the plain Bohr model [0])). [0] https://en.wikipedia.org/wiki/Bohr_model#Derivation https://en.wikipedia.org/wiki/Bohr_model#Derivation
- ForOldHack 2y agoThanks for looking that up. I was going to look it up when I was not on mobile. Imagine 500 years in the future when we have laptop particle accelerators... We may have whole diffent reality around 'strange'. The line from the remake of 'the man who fell to earth.' "He has miscalculated the chirality."