Wednesday, August 22, 2012

Element of the Month: Bohrium!

August's Element of the Month:

Bohrium!
Bh
107

Atomic Mass: 262 or so amu
Melting Point: Unknown (!)
Boiling Point: Unknown (!)

Bohrium is one of the fakey elements, so fakey in fact that it was not synthesized until 1981 (or possibly 1976) and not officially given its bona fides by the Fakey Element Referees (the "IUPAC/IUPAP Transfermium Working Group") until 1992. Its name was not officially agreed upon until 1997. Until then, "Bohrium" was in contention against "Nielsbohrium" for Element 107, and "Bohrium" was also in the ring with "Dubnium," which eventually won out, for Element 105. References from your school days might well have called Bohrium "Unnilseptium" (IUPAC/IUPAP Tranfermium Working Group argot for "Unnamed Element 107") or, if your school days were quite a ways back, "eka-rhenium," or perhaps they would have acted, quite correctly, as if no such thing existed.

Does such a thing exist? Occasionally, kind of. Possibly right now, in quantities that could very generously be described as "trace." The most stable isotope of Bohrium has a half-life of 61 seconds. Let's review the concept of "half-life": if you had a pound of Bohrium on your kitchen table, 61 seconds later half of it would be gone. Well, it wouldn't be absent, but it would have "decayed," which is to say shed one or more of its artificially added-on protons and transformed into another, marginally less fakey element. After 122 seconds, you'd only have a quarter pound of Bohrium left, as well as a number of other problems that would be beginning to demand your attention.

If this relentless erosion of your Bohrium stash seems unfair, keep in mind that other Bohrium isotopes have half-lives of, say, 8 milliseconds. If your pound of Bohrium was composed of that isotope, after a single second you would be down to 1/42,535,296,000,000,008,192,304,928,032,936,392,744 of a pound, which is to say 1/2,658,456,000,000,000,512,144,808,752,496,712,984 of an ounce, of Bohrium. At that point you would have (mostly) a pound of Dubnium that was itself rapidly shedding protons on its way back down to a lesser state of fakiness.

Lest this little thought experiment cause confusion, I should clarify that all of the Transfermium Working Groups in all the physics labs in the world, put together, have never produced anything even remotely resembling a meaningful fraction of a pound of Bohrium.

The Centerfold!

And by the way, it's not like Bohrium, Element 107, is the fakiest of the elements. They've synthesized them all the way up to Element 118, and indeed one of the ways than Bohrium has manifested itself is as part of the stepping-down process from even fakier Elements such as Meitnerium (#109) and Darmstadtium (#110). (And even more by the way: if you are used to #112, Copernicium, being the highest-numbered named element, then you missed the party this May when Flerovium (#114) and Livermorium (#116) were given their wings by the IUPAC/IUPAP boys.)

By modeling and extrapolating from real elements, it is both possible and diverting to predict what chemical properties a fakey element would have, if it existed, and what chemical reactions it could undergo. In this enterprising spirit, at least one team has brewed up a batch of Bohrium and then exposed it to chlorous acid. I picture guys in white coats muttering "come on Come On COME ON!!!" as they pour the acid onto the Bohrium, knowing that the Bohrium is decaying into not-Bohrium like sand slipping through their fingers. But they brought their chemicals together in time, and were able to create and detect a compound: bohrium oxychloride, which was apparently a lot like rhenium oxychloride, only much, much, much more expensive. It's interesting, don't you think, that even when pushed into fairly contrived configurations, the stuff of matter seems to still play according to a relatively succinct rulebook.

3 comments:

mrs.5000 said...

I am wondering about the "number of other problems" that would begin to demand my attention, if I had a pound of Borium on our kitchen table. I would hate to be unprepared. I'm assuming it would be best to put dishes away, and perhaps shut the cat in the basement beforehand?

Kenneth Noisewater said...

I was going to say something about that element sounding like boring or boredom, but that would just be rude.

Keep the nerdy stuff coming! I always learn something from Big Mike.

Michael5000 said...

Mrs.5000: Frankly, I am wondering that too. I do not have a satisfying answer. Also, I realized at some point that I was visualizing a much-too-large one-pound brick of Bohrium. Keep in mind that it would have to be heavier than lead, literally and substantially.

Bohrium transforms into Dubnium through alpha decay, which is to say by shedding alpha particles, which is to say by emitting alpha radition. Now, everybody says that alpha radition/waves/particles [duuuuude...] is pretty innocuous; they/it can be blocked by a sheet of paper, but doesn't really need to be because it/they lose(s) their oomph after traversing a few inches of air.

But, normally folks talking about alpha decay are thinking about substances that shed a particle every once in a blue moon, and not about every molecule in a pound-size brick of material losing an alpha particle simultaneously. My intuition tells me that in this latter situation, such a great deal of energy would be directed outward to the table surface and the surrounding air. I would expect rapidly rising local temperatures, possibly in the form of the table bursting vigorously into flame, possibly in the form of a perfectly spherical blast of annihilating heat and light energy expanding with great speed from the original site of the Bohrium. But I'm just guessing.

Now, if I'm right about either of these things, you would also be worried about Bohrium getting away from you through billows of smoke or borne on the explosive blast. Even if I'm wrong, though, the integrity of your brick is going to be problematic during the decay process. See, when alpha particles jump out of a nucleus, there is a recoil effect -- more or less an equal and opposite reaction within the nucleus as a couple of protons take off at an extremely high speed. The effect of all this recoil happening at once might do, well, who knows? It might cause explosive disintigration, it might cause the brick to leap into the air, it might cause it to deform like hot taffy. Hard to say.

Meanwhile, it's important to remember that as soon as an alpha particle is shed, your molecule of Bohrium is now a molecule of Dubnium. Dubnium will want to decay too, not as fast as Bohrium but, I think you'll find, with distressing speed. And Dubnium doesn't always undergo alpha decay; it sometimes emits beta particles, which are much "worse" than alpha particles in terms of hanging out around them. And this stepping down procedure will keep going until you finally end up with something relatively safe and stable, such are Uranium. Or Plutonium.

Hope this helps. My advice is, leave the synthentic elements to the pros.


Dr. Ken: Nothing boring about a perfectly spherical wave of annihilation! But it's just a guess. I'm not making any promises.