5 ms·
Hypothetically, is it possible that periodic table is infinite, its just too hard to create other elements?
by ssijak 2y ago
Hypothetically, is it possible that periodic table is infinite, its just too hard to create other elements?
- mglz 2y agoHard to create and the results seem to get more and more unstable, making it very hard to do any science on them. However there is a theorized "island of stability", where superheavy elements might stick around for a bit longer: https://en.wikipedia.org/wiki/Island_of_stability https://en.wikipedia.org/wiki/Island_of_stability
- delecti 2y agoThat theorized island is centered around elements we've already discovered though, being in the range of ~110 protons. So element 120, being discussed, is already well past that point.
- seanw444 2y agoWhy couldn't there be multiple islands of stability, and why couldn't they be way higher in proton count? All you should really need is a fairly "balanced" nucleus, right? Is there some property of larger nuclei that makes them increasingly more difficult to balance?
- mannykannot 2y agoI just posted some notes on this in another reply: https://news.ycombinator.com/item?id=41057818 https://news.ycombinator.com/item?id=41057818
- adrian_b 2y agoThere are with certainty multiple islands of stability, when each layer of nucleons becomes complete. However, in each island of stability the most stable element is much less stable than the most stable element of the previous island of stability. Therefore in most higher islands of stability the decay times will become too short. It is possible and rather likely that only the first undiscovered island of stability may contain relatively long-lived elements, e.g. with half-lives over one second. An island of stability finishes at bismuth, which is radioactive, but which has a huge half-life. The next island of stability contains the long-lived thorium and uranium and the still relatively long-lived neptunium and plutonium, after which the half-lives decrease very quickly. Whichever will be the longest-lived elements of the next island of stability, their half-lives will be many orders of magnitude smaller than those of thorium and uranium.
- daedrdev 2y agoNotably Lead-208 has magic numbers of protons and neutrons so is extra stable, with lead itself representing the last stable element
- adrian_b 2y agoThe next magic numbers after 82 are not known with certainty. Nevertheless, it was usually supposed that 126 is the next magic number for protons, in which case it has not been reached yet. Other possible values, from more recent computations, are 122 and 124, also not reached yet. Moreover, the isotopes that are the most stable for the already synthesized elements are expected to have more neutrons than in the isotopes that have been successfully produced. So it is not impossible that an "island of stability" might have already been reached, but only with isotopes that have so few neutrons that they remain outside the zone of stability.
- HPsquared 2y ago"IUPAC defines an element to exist if its lifetime is longer than 10^−14 second, which is the time it takes for the atom to form an electron cloud.[7]" If the nucleus disintegrates before electrons can cluster around it, you're not really in the realm of chemistry any more. Chemistry is all about those electrons.
- staunton 2y agoOne could argue that neutron stars are nuclea... If so, at least nuclea production doesn't stop any time soon. Probably you wouldn't call it an atom though...
- adrian_b 2y agoThe neutron is really an additional chemical element, the element with Z=0. It belongs in the group of noble gases, together with helium, neon, argon, krypton, xenon and radon. Like radon, it is unstable, but also like radon it is widespread in nature as a product of radioactive decays. The element with Z=0 has multiple isotopes, like any other chemical element. Unlike for any other element, the possibility of gravitational stabilization makes the number of its stable isotopes potentially infinite. The neutron stars can be seen as belonging to the isotopes of the chemical element with Z=0.
- WantonQuantum 2y agoInterestingly, neutron stars do contain a small percentage of protons.
- adrian_b 2y agoHowever, those protons are not stable. Their concentration is the result of the equilibrium between neutrons that decay into proton and electron pairs and proton-electron pairs that recombine into neutrons. The complete neutron star still behaves like a giant nucleus with null electric charge, i.e. with Z=0.
- 2y ago
- AnimalMuppet 2y agoDefine "periodic table". The operating definition has been "a list of all elements that humans have discovered and/or made". By that definition, it is not currently infinite, nor will it ever be. If instead you define it to mean "all elements that might theoretically exist under all theories of physics that are not currently definitively ruled out", then it may be it infinite. But that's not the normal definition.
- breck 2y agoThis. We give too much importance to the "Periodic Table". It's just a man-made microlang. Nature is unconcerned with it. There is much more beyond it. P.S. While I'm criticizing the PT, might as well mention that I think we've probably done people a diservice by giving misnomer names like "Hydrogen" and "Oxygen" to these elements, which is completely disconnected from the mathematical beauty and patterns that those names represent.
- snapcaster 2y agoWhat would you name Hydrogen and Oxygen?
- NeoTar 2y agoInverting the names makes sense. Wikipedia: Oxygen > Lavoisier renamed 'vital air' to oxygène in 1777 from the Greek roots ὀξύς (oxys) (acid, literally 'sharp', from the taste of acids) and -γενής (-genēs) (producer, literally begetter), because he mistakenly believed that oxygen was a constituent of all acids. Hydrogen comes from ‘water’, which contains hydrogen and oxygen. So, since all acids must have Hydrogen, Oxygen is actually a better name for Hydrogen. This then leaves the name Hydrogen free for Oxygen.
- breck 2y agoGreat question. Singtium and Octium, perhaps.
- dredmorbius 2y agoWasserstoff and Sauerstoff, obv.
- jmyeet 2y agoIt 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."
- blindriver 2y agoThere’s a hypothesis that I heard back when I was in high school 40 years ago that maybe the atoms start stabilizing again once you go high enough in the atomic number. It was just a hypothesis but kind of cool to think about.
- px43 2y agoIt's called the "Island of Stability" : https://en.wikipedia.org/wiki/Island_of_stability https://en.wikipedia.org/wiki/Island_of_stability
- blindriver 2y agothank you!
- ForOldHack 2y agoIt's quite possible for anything to happen. Neutron stars are based on a theory. Now it happens that that particular theory was fromulated by some of the most brilliant minds I can imagine. Gravity and the strong neuclear force can do things we cannot fathom. Things may be going on in the interior of neutron stars... The macro stars and the micro. I for sure thought that 118 was the limit, and again, this has been a life long interest of mine. I have the isotope chxart on the wall at home. P.s. kudos for paying attention in school. P.p.s extra thanks the people who kept the Laurence hall of science going, and it's periodic table working.
- russdill 2y agoNo, at some point gravity becomes important and you can make enormous atomic nuclei. Neutron stars are about 5% protons. I don't think people would think these would count though as it's not like you can have chemistry between neutron stars and the electrons do not behave like they do in atoms. And past another point you just get a black hole. So clearly there is a limit. Either bounded by the point where gravity becomes dominant or when you get a black hole.
- jessriedel 2y agoFor sufficiently heavy nuclei, you would cease to have any bound states way, way before gravitational effects were important.
- zelphirkalt 2y agoNeutron stars certainly do have attraction ... don't see why they can't have some chemistry as well. They seem cool after all.
- mystified5016 2y agoChemistry happens in the electron cloud surrounding the atoms. Specifically the orbitals. While there may be some electrons in and around a neutron star, they are not organized into orbitals. By definition, a neutron star cannot undergo chemical reactions. What happens in neutron stars is somewhere between nuclear reactions and quantum effects. Both of which are decidedly not "chemistry" in the way most people use that word. More generally, only normal atoms can undergo chemistry. All of chemistry depends on the arrangement of electron orbitals. Once you leave that domain, you're in an entirely different field of physics.
- russdill 2y agoThe problem isn't attraction, the problem is they lack meaningful repulsion. They would just collide.
- philipov 2y agoNo. Regardless of anything about definitions or stability that other commenters have mentioned, the mass of possible elements is bounded by General Relativity. There is a theoretical upper bound on the mass of an elementary particle at which it will collapse into a black hole. Fundamental particles can not be heavier than the Planck Mass, and Atoms should have a corresponding value at which they will likewise collapse into a black hole. Black holes do not satisfy even the loosest definition of an element.
- exe34 2y agothat's probably a lot higher than the sort of atomic number we can realistically reach in the lab?
- philipov 2y agoOh, it's immensely massive compared to anything that's likely to possibly exist as an element. But in proving something is finite, it doesn't matter if we overshoot by a million million percent, all we have to do is establish any bound at all. We don't have to engage with the question of what we can do in a lab, because the question only requires any theoretical limit to exist. It may be difficult to predict just how far we can go in a lab, but the existence of black holes means there must be some limit.
- arcadi7 2y agononsense . heavy nuclea are bound states of many constituents . no different from grain of salt . grain of salt can be much heavier than planck mass (which is about few micrograms
- arcadi7 2y agonucleus is extremely fluffy by general relativity standards . for black holes the mass and size are linearly proportional . the solar mass black hole has few mile size and has density few times smaller than that of the nucleus . solar mass is about 10^57 protons or about 10^55 heavy nuclea like uranium . so in order for general relativity to be important for uranium nucleus, it has to have a size of 5 miles/10^55 or about 10^-49 cm . instead heavy nuclea have a size of about 10^-15 cm . so nuclea are 34 orders of magnitude fluffier than they should be for any general relativity to be of any relevance . they are as good as grain of salt
- mppm 2y agoNo, the stability of elements peaks at iron and nickel and declines again after that. If you look at the curve of binding energy per nucleon [1], the trend is quite obvious. Note in particular that at some point past uranium, the average binding energy declines to below that of helium, making the isotopes extremely susceptible to alpha particle emission. There are some "islands of relative stability", where heavy elements are stabilized by "magic numbers" of protons and neutrons -- which is why thorium and uranium are so long lived. But we can be quite certain that there is no such thing as Element 200. [1] https://en.wikipedia.org/wiki/File:Binding_energy_curve_-_common_isotopes.svg https://en.wikipedia.org/wiki/File:Binding_energy_curve_-_co...
- AdamH12113 2y agoWhy does that graph look like it's upside-down? Shouldn't having more binding energy per nucleon make an isotope less stable, not more? Are the energies implied to be negative potential energy?
- HPsquared 2y agoBinding energy = energy released when the nucleons bind together. In other words, energy required to break them apart.
- pfdietz 2y agoIgnoring neutron stars or exotic states of quark matter, I think conventional nuclei will become effectively unbound to proton or neutron emission if sufficiently massive.
- empath75 2y agohttps://en.wikipedia.org/wiki/Continent_of_stability https://en.wikipedia.org/wiki/Continent_of_stability At some point it becomes "quark matter" and might exist in collapsed stars.
- ars 2y agoAt some point the element will decay faster than it can exist. There are already subatomic particles that get created on one side of the particle and decay on the other, i.e. their lifetime is shorter than that time it takes for light to travel from one side of the particle to the other. Atoms are much bigger than subatomic particles, so they have to live even longer in order to exist.