It's all about stability. If you try and jam too many protons and neutrons together, they won't stay together for long. If the nucleus disintegrates before there's time for electrons to form and act like a chemical element, it's not really in the realm of chemistry any more.
"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]"
Don’t we all. This is the reason general relativity and the standard model don’t fit under one framework (string theory has currently failed to combine them in a testable way), we don’t understand why or when gravity starts to become important.
I hope the universe lets us upgrade the periodic table once we reach 120. Maybe we earn a new alpha constant that enables a whole new level of new elements for long distance space travel.
The point about stability is that as the curve of stability is not a straight line. That is as the number of nucleons increases, you need proportionally more and more neutron to be stable. So you cannot just smash small nuclei together to form bigger ones. Somehow you need to add some extra neutrons.
The below linked video is about a fraudulent attempt by Victor Ninov to claim success at making 116 and 118, but explains the experiments, I think, quite well.
For some background on the quest to discover new elements, I highly recommend this video: https://www.youtube.com/watch?v=Qe5WT22-AO8. The main story about Ninov's fraud is pretty interesting, but the beginning does a good overview of the recent history.
Soon as you said Ninov, I knew whose video that was immediately. BobbyBroccoli seems to make rather good documentaries on weird subjects, and they seem to be pretty well researched.
The highest atomic number of any synthesised element appears to be Oganesson: https://en.wikipedia.org/wiki/Oganesson . Only 5 atoms have ever been synthesised. It's speculated to be a solid at room temperature despite belonging to the "noble gas" family. Chemistry is fascinating.
Are there even transitionally stable conditions in other places in the universe where these elements exist for more than fleeting time?
I would imagine in conditions of high heat, plasma, RF energy and pressure many things "exist" but I don't see that as quite the same. I guess if their spectral line emissions from stars says they are a continuum of existence then thats something, but I wondered if there were wierd islands of stability e.g. inside crystal lattices under pressure, or in solution in some wierd, non-plasma state. Absent an observer round that star we can't know but can we hypotheise physical states which would let it be?
Neutron stars are made of a solar mass of neutrons and protons packed so tightly together that they're almost like a single giant nucleus. They can collide and shatter into countless particles of every imaginable heavy element. Of course most of these quickly decay but they decay into other heavier things that are more stable. This is possibly where heavy elements in our solar system such as uranium, platinum and gold came from. If we could visit Earth shortly after its formation 4.5 billion years ago maybe we'd see trace amounts of even more exotic elements! https://en.wikipedia.org/wiki/Neutron_star_merger#Distributi...
Every time I read references to one of the transuranic elements, I can't help but want to share this absolutely delightful narrative about actually building a wall of bricks from each element in the periodic table. Hilarious stuff.
While we hear a lot about isotopes (nuclei with same proton count but different neutron count), we don't hear as much about nuclear isomers (nuclei with the same proton count and same neutron count, but somehow having different configurations).
1. Are nuclear isomers a thing?
2. Corollary: Could it be the case that some nuclei are stable and others are unstable, even though they have the same numbers of protons and neutrons?
TL;DR: accelerating titanium ions to 0.1 c into a plutonium target made 2 atoms of Livermorium.
The difficulty here is that such a collision leaves the result very "hot", so it tends to decompose. This tendency is minimized by reducing the energy of the incoming ion, but that reduces the rate of fusion.
Needless to say, this doesn't present much in the way of practical benefit from producing some new science fictional material. It's purely of scientific interest.
The tangent on manipulating Titanium in order to prepare it for the beam was more interesting to me, and IMHO sounds like a much more practical and potentially useful bit of knowledge coming from this.
Titanium is a pita to work with.
But also... the 'island of stability' is fascinating, and I think we have to assume that we don't know enough about the Strong Force until we either prove it exists and is reachable, or doesn't/isn't.
The problem with the strong force is that it doesn't have some nice tidy description, like the inverse square law for the electrostatic force.
It's spin dependent, and not just involving interactions of pairs of nucleons. There are at least three-nucleon terms in the potential. It looks like something accidental, not elegant or designed. It just "happens" to give stable nuclei that end up allowing something like us to have come into existence. I get the feeling of anthropic effects on display.
Genuinely want to know, what is the scientific interest here? The synthesis of super heavy elements always seems to be the same story, they detect its presence for a tiny fraction of a second, and then it decays away. What is learnt from doing this?
Well, I'm sure there's all sorts of interesting nuclear physics to be learned like island of stability stuff, but given the context of who's doing this work and competing for credit - I guess even out of the cold war context it's a great way to show that 1) my country is better than your country at nuclear physics get rekt or 2) my country and your country get along now, look at us do nuclear physics together or 3) what's up, new player here, btw I'm also good at nuclear physics check out this element I found.
Or in this case 4) oh no your country and my country don't get along anymore! time to asset scientific dominance by "re entering the super heavy race" (https://www.science.org/content/article/u-s-back-race-forge-...) and getting the department of energy to start funding this again so we're back on top.
Key point I missed: Livermorium here is just a benchmark for the new titanium-beam process (having been discovered in 2000.) Actually using it to attempt to produce element 120 is a future step.
Yes; they had to demonstrate they could form and accelerate titanium beams (made difficult by the high temperature needed to sufficiently vaporize titanium.)
I think there's a bit of institutional momentum here, along with the historical realization that "finding new elements" was really valuable in the past (not that these new elements would be valuable). There's also a bit of international competition.
Readit News
"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]"
https://en.m.wikipedia.org/wiki/Island_of_stability
https://en.m.wikipedia.org/wiki/Superheavy_element
(Edit: this was intended in response to ssijak's question about the theoretical limits)
And then 1.4 Solar masses is the upper limit. [1]
[0] https://physics.stackexchange.com/a/143174/43351 [1] https://en.wikipedia.org/wiki/Chandrasekhar_limit
P.S. Quote from the link:
> Would this black hole cause the universe to collapse? Hard to say.
Deleted Comment
https://www.youtube.com/watch?v=Qe5WT22-AO8
[On The Way To Super Elements](https://archive.org/details/FlerovIlyinovOnTheWayToSuperElem...)
Deleted Comment
https://en.wikipedia.org/wiki/Unbinilium
I would imagine in conditions of high heat, plasma, RF energy and pressure many things "exist" but I don't see that as quite the same. I guess if their spectral line emissions from stars says they are a continuum of existence then thats something, but I wondered if there were wierd islands of stability e.g. inside crystal lattices under pressure, or in solution in some wierd, non-plasma state. Absent an observer round that star we can't know but can we hypotheise physical states which would let it be?
https://englishatlc.com/wp-content/uploads/2016/03/randall-m...
1. Are nuclear isomers a thing?
2. Corollary: Could it be the case that some nuclei are stable and others are unstable, even though they have the same numbers of protons and neutrons?
The difficulty here is that such a collision leaves the result very "hot", so it tends to decompose. This tendency is minimized by reducing the energy of the incoming ion, but that reduces the rate of fusion.
Needless to say, this doesn't present much in the way of practical benefit from producing some new science fictional material. It's purely of scientific interest.
Titanium is a pita to work with.
But also... the 'island of stability' is fascinating, and I think we have to assume that we don't know enough about the Strong Force until we either prove it exists and is reachable, or doesn't/isn't.
It's spin dependent, and not just involving interactions of pairs of nucleons. There are at least three-nucleon terms in the potential. It looks like something accidental, not elegant or designed. It just "happens" to give stable nuclei that end up allowing something like us to have come into existence. I get the feeling of anthropic effects on display.
Or in this case 4) oh no your country and my country don't get along anymore! time to asset scientific dominance by "re entering the super heavy race" (https://www.science.org/content/article/u-s-back-race-forge-...) and getting the department of energy to start funding this again so we're back on top.