Element 118

[Blob]

Element 118 has been created in experiments conducted at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia by a collaboration of researchers from Russia's Joint Institute for Nuclear Research and the Lawrence Livermore National Laboratory in California.
Element 118, the heaviest element yet found, was produced through collisions that fused together Californium and Calcium atoms. Although element 118 is too unstable to detect directly, the presence of daughter elements resulting from the decay of element 118 gave clues to its fleeting existence.

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[antoniseb]

The article suggests that it was made with Cf₂₄₉ and Ca₄₈. I'm wondering if there might not be a worthwhile advantage to trying to make it with a more short-lived Californium isotope, such as 252 or even 254. The superheavies that we've been discovering are all at the low tail of the bell-curve for expected most-stable neutron-proton ratios.

[trinitree88]

How about naming it California-or-bustium?

[TriangleMan]

Wasn't E-118 supposed to be the UFO anti-gravity element, or something like that? How about they call it woowooium!

[The Supreme Canuck]

Is there a theoretical limit to how many elements can be artificially created? If not, what purpose is served by continuing? Once we get up to, say, element 69,478, it starts to get a little tiring.

[Romanus]

^
I read onc (though the reference escapes me) that it's theoretically possible to go up to atomic numbers as high as the 190s. Beyond that though, it would supposedly be physically impossible for the strong force to hold them together.

[Gsquare]

..... How about they call it woowooium!

How about..... almostimpossibilium ?

[swansont]

How about naming it California-or-bustium?

bustium would have a definite quadrupole moment, would it not?

[Doodler]

How about..... almostimpossibilium ?

Nighunobtainium

[Chuck]

Costtoomuchium.

[Doodler]

Are any of these hundred teen elements stable for any useful length of time?

Aside from the fact that its fascinating to see what their structures are like, what real practical purpose do these higher level elements have?

[Gsquare]

...., what real practical purpose do these higher level elements have?

Impracticalium

[parallaxicality]

Wasn't E-118 supposed to be the UFO anti-gravity element, or something like that? How about they call it woowooium!

I believe that was 115. Wasn't there a big hoohah about 115 being in the Island of Stability, and that it would stay around a lot longer than other eka-elements? What happened about that?

Also, isn't there a point where we won't be able to go on any further? I mean, eventually we'll be so far along the table that in order to go any heavier we'd have to start off with the elements we couldn't make stable in the first place.

[antoniseb]

Are any of these hundred teen elements stable for any useful length of time? Aside from the fact that its fascinating to see what their structures are like, what real practical purpose do these higher level elements have?

Stable 11x elements? Not in the isotopes that we've been able to create so far. To some extent what we've been doing is like trying to make Oxygen-12. The number of neutrons is way too low, and so it falls apart very fast.

The longest lived we've seen so far is an isotope of 114 that has a half-life of 2.6 seconds This is the peak number of protons for the island of stability. 184 neutrons is what you'd expect to make the element the most stable it can be (Ununquadium₂₉₈), but we are very short on neutrons for making that. BTW, 120 and 126 protons also should work well with 184 neutrons.

[tofu]

Wasn't there a big hoohah about 115 being in the Island of Stability, and that it would stay around a lot longer than other eka-elements? What happened about that?

Last week's NOVA had a bit about this. Current theory suggests that you need a certain magical number of neutrons to hold these elements together. We used to believe that the nucleus was just a mash of protons and neutrons, but now they think that there is order in the nucleus, just like how electrons order themselves into energy levels. You can't just add any random number of electrons to an element, it has to be a number that will form stable energy levels.

So anyway, based on what I saw on NOVA, what they have created here is a nucleus with too few neutrons. So the half-life turns out to be less than 1 second. The theory states that, inside the island of stability, if you have the right number of neutrons, the half-life should be billions of years. So, we'd be looking at elements that might be useful for something. I have no idea how they are going to get those extra neutrons though.

[Doodler]

Stable 11x elements? Not in the isotopes that we've been able to create so far. To some extent what we've been doing is like trying to make Oxygen-12. The number of neutrons is way too low, and so it falls apart very fast.

The longest lived we've seen so far is an isotope of 114 that has a half-life of 2.6 seconds This is the peak number of protons for the island of stability. 184 neutrons is what you'd expect to make the element the most stable it can be (Ununquadium₂₉₈), but we are very short on neutrons for making that. BTW, 120 and 126 protons also should work well with 184 neutrons.

I see, so are they actually trying for the creation of more stable isotopes, or are they racing to see how many protons they can cram in a nucleus at one shot? I can see why they'd keep trying to stabilize an isotope, if they can get a high energy material stable for any appreciable length of time, you can use it for some extremely high energy fission fuel, but just slapping protons together for a femtosecond snapshot seems a bit of a waste.

I don't mean to question the pursuit of knowledge for its own sake, but yelling "Eureka!" over something that exists for so little time its not possible to be consciously aware of it seems a little out there. I'd be a little more impressed over the discovery of a form of element 114 that could stick around for a few years, than an element 118 that's stable for all of a few Planck intervals.

[antoniseb]

I don't mean to question the pursuit of knowledge for its own sake, but yelling "Eureka!" over something that exists for so little time its not possible to be consciously aware of it seems a little out there.

It can be useful in terms of validating ideas about nuclear forces and refining constants. Having a better grasp of these things makes it safer to extrapolate into the real of supernova explosions and other topics of interest to astronomers.

[Blob]

Hum,
more...

In searching through 10^19 collision events, how do you know you have found a new element? Because of the clear and unique decay sequence involving the offloading of alpha particles, nuclear parcels consisting of two protons and two neutrons. In this case, nuclei of element 118 decay to become element 116 (hereby itself discovered for the first time), and then element 114, and then element 112 by emitting detectable alphas. The 112 nucleus subsequently fissions into roughly equal-sized daughter particles.

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[TriangleMan]

I don't mean to question the pursuit of knowledge for its own sake, but yelling "Eureka!" over something that exists for so little time its not possible to be consciously aware of it seems a little out there.

But they wouldn't know for sure how long it lasts until they make it. Provided the experiment is validated I can't see too many other labs continuing to make this E118 isotope for years to come but it is still an advancement for someone to make it for the first time to see what happens.

[Peter Wilson]

... I'd be a little more impressed over the discovery of a form of element 114 that could stick around for a few years, than an element 118 that's stable for all of a few Planck intervals.

Plancktimium?

[Doodler]

Plancktimium?

[Fomalhaut]

The article suggests that it was made with Cf₂₄₉ and Ca₄₈. I'm wondering if there might not be a worthwhile advantage to trying to make it with a more short-lived Californium isotope, such as 252 or even 254. The superheavies that we've been discovering are all at the low tail of the bell-curve for expected most-stable neutron-proton ratios.

While 252-Cf or 254-Cf do have more neutrons available for a superheavy products, they are highly radioactive (short half-life and large spontaneous fission decay branch). It would be difficult to make enough of either of them to make a target, and the target would be exceedingly difficult to work with.

[Romanus]

I think the real drive behind element transmutation is a kind of Mallory-esque "because it's there..." sentiment.

[Peter Wilson]

...because it could be there

[baric]

The longest lived we've seen so far is an isotope of 114 that has a half-life of 2.6 seconds This is the peak number of protons for the island of stability. 184 neutrons is what you'd expect to make the element the most stable it can be (Ununquadium₂₉₈), but we are very short on neutrons for making that. BTW, 120 and 126 protons also should work well with 184 neutrons.

You apparently know a bit about the theory behind this, so I'll ask... Are there simulations/projections on the projected half-life on something like Ununquadium₂₉₈?

[Swift]

This wikipedia article has a pretty good explanation of the Island of Stability.

I don't mean to question the pursuit of knowledge for its own sake, but yelling "Eureka!" over something that exists for so little time its not possible to be consciously aware of it seems a little out there. I'd be a little more impressed over the discovery of a form of element 114 that could stick around for a few years, than an element 118 that's stable for all of a few Planck intervals.

I like antoniseb's answer, but I also think that basic research for its on sake is important too. I could argue that much of astronomy research is of no practical use too.

If you check out the link, you will find that some of the 1xx's have half-lives of seconds. Not years, but a lot longer than a few Planck moments. It is also believed that even these are not at the "center" of the island. The big challenge is finding a "path" to get there.

As to The Supreme Canuck's question as to an upper limit, it seems likely that there is an upper limit to obtaining new elements by this method. I suppose at the next nuclear energy level above where work is now being done, you would again reach a point of a filled shell, but it is hard to imagine a method of even reaching it.

[antoniseb]

Are there simulations/projections on the projected half-life on something like Ununquadium₂₉₈?

I don't know of any, but that doesn't mean they aren't out there. I'm not a practitioner here, just a former member of a nuclear physics team from decades ago (actually did work on the shell model of the nucleus) who has kept a mild interest.

The various websites on the subject indicate that the act of completing the shells changes the nucleus from being rugby ball shaped to being spherical. This spherical shape is supposed to be much more stable, by not having areas where some nucleons (protons especially) are removed from the strong nuclear force from many of the members of the nucleus, but still feeling the repulsive electrical charge.

The details of how long a given nucleus might last have to do with the fuzzy specifics of the range of the nuclear forces and actual packing density of the nucleons in such a large nucleus. Predictions depend on some measurements and guesses, where the precision of the measurements results in a wide range of answers to your question.

[Doodler]

I like antoniseb's answer, but I also think that basic research for its on sake is important too. I could argue that much of astronomy research is of no practical use too.

Oh, don't get me wrong, I'm not opposed to pursuit of pure research, but there's something of a difference between whacking enough subatomic particles together to say "Yay! We did it!" when you could do the same math on paper. What I didn't know previously, that Antoniseb and others cleared up for me was the search for islands of stability and some means of getting enough neutrons in the mix to try reaching it. Even if the elements are extremely transient, the fact that there's a practical aspect of babystepping their way towards a means of creating stability opens up part of the big picture I didn't know about.

The picture's a little more complicated than I was originally lead to believe, that misconception's been addressed.

[swansont]

Oh, don't get me wrong, I'm not opposed to pursuit of pure research, but there's something of a difference between whacking enough subatomic particles together to say "Yay! We did it!" when you could do the same math on paper.

That's a problem, though: doing it on paper is not a substitute. You don't know if the model you do on paper is correct until you go into the lab and confirm it. You have to see if the physics is complete, or if there is something new out there, and there are plenty of examples of experiment finding something different from what the theory predicted.