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Science

Bismuth No Longer the Heaviest Stable Element 78

Posted by michael from the first-slashdot-story-to-use-the-word-bismuth dept.
forii writes "Bismuth-209 was commonly thought to be the heaviest stable element. But now Physicists have discovered that Bi-209 actually is unstable and decays with a halflife of 2*10^19 years. This means that the average 8oz (237ml) bottle of Pepto-Bismol contains one decay event every 36 hours or so."
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Bismuth No Longer the Heaviest Stable Element More

Bismuth No Longer the Heaviest Stable Element

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  • be sure dont use this element in any project that has a life span of > 2*10^19 years!

  • Pepto-Bismol DANGER!!!

    [shock-rag wire service] Scientists discover that bismuth, a major component of Pepto-Bismol , is RADIOACTIVE and decays into the TOXIC POISON thallium.

    While the decay rate is the slowest observed to date and, in fact, sets a record, it is noted that NO MINIMUM SAFE EXPOSURE LEVEL has been established for radiation exposure, and there is NO CURE for thallium posioning.

    • Yeah and the article will end with a pitch to sell some Colloidal Silver machines. After all Colloidal Silver is natures antibiotic.
    • OMG, you're right! At one event per 36 hours, it's practically a fucking Omega Particle!

      Someone call Starfleet! *KILL IT! *KILL IT!

      (*read: start a new government agency dedicated to the analysis and monitoring of this tool-of-terrorists; fund a few dozen fact-finding junkets, c/o the taxpayer; draft an array of pointless laws regarding Bi research, don't forget to call the religious end-of-world nutters for their valuable insight; end up hiring a PR agency to divert attention away from the fact that yo
      • > At one event per 36 hours

        Remember, that's just an average. Your experience may be different. It could decay all at once just after you swallow. You can't be too careful.
        • that's just an average... It could decay all at once just after you swallow

          True, you're far more likely to have the hydrogen atoms in a glass of water spontaneously fuse after you drank it. If the bismuth decayed all at once it would kill you, but if hydrogen fused all at once it would kill everyone in a 50 mile radius. :)

          -
          • Also, do not drink orange juice or eat bananas: these foods are rich in potassium. Naturaly occuring potassium has a lot (several %) of radioisotope. Its beta radiation is soft and decay slow, but the generated heat is enough to keep the Earth molten inside.

            So, fruits are bad - fruits are radioactive. I knew it instinctively since my childhood.

  • Actually... (Score:2, Interesting)

    by Mensa Babe ( 675349 )

    Bismuth-209 was commonly thought to be the heaviest stable element.

    Actually, most of the scientists believed it was stable, however not everyone. (Some of them were considered "crackpots" by the rest of the community, but the point remains valid, even if somewhat less so.) Try a Google search [google.com].

  • The obvious question that immediately came to my mind was "what is the new 'commonly-accepted heaviest stable element'"? And that question doesn't seem to be answered by the posting or the article. Anybody know the answer? Thanks.

    • Re:And the new winner is? (Score:1)

      by Anonymous Coward
      Lead. Pb(208)
    • If you look at the periodic table, the answer is obviously the next smaller element, lead, which is what most of the heavier elements eventually decay to.

      • It might not nessisarly be lead, (although I'm pretty sure your right), since there could have been some lighter isotope of bismuth which was stable (208, 207, etc).
        • True, but then it would be lighter than lead. D/\ Gooberguy
          • actually, if it were bismuth 208, it would still be heavier then lead (208), since a proton wieghs more then a neutron. By the way, this is all academic, since Bismuth 208 is the only (realitively) stable isotope anyway

  • Thanks for posting this after markets are closed (Score:1, Funny)

    by Anonymous Coward
    All that portfolio I had of Bismute stocks, bonds and futures are going to be worthless by Monday morning. Knew should've bought oxygen - stable although slow-growth stock, my broker told me people are always gonna need oxygen, but no, I wanted the red-hot high-yield stock.
  • Nobody ever worries about Francium poisoning.
    • GAITHERSBURG, MD
      22 May 2003

      Today, the National Institute for Standards and Technology [nist.gov], the civilian agency of the US Government responsible for researching and making available data concerning the physical properties of substances including chemical elements, annouces the discontinued use of francium as the name of the 87th chemical element.

      "It's just not appropriate to continue to refer to an element by the name of a nation whose inaction is tantamount to condoning terrorism," said Dr. Hratch G. Semerjian, director of the Chemical Science and Technology Laboratory. "We decided that it would be better to refer to the 87th element as Freedomium in honor of those who died to secure the liberty of our country.

      Asked if the agency would once again return to calling the 87th element francium, Semerjian said that the element would not return to its former name. "We are prepared to take whatever action is necessary to liberate any element whose nomenclature is derived from a repressive regime."

      -
      • Perhaps "Freedonian" would be better - though it isn't quite "Freedom" and doesn't quite follow the usual naming convention ("ium"). Its a bit more pronounceable and rather more euphonious.

        But best of all, it not only swats those durn Freedomch types, it commemerates the great citizens of Freedonia, ever fighting for their country - led by the most excellent Rufus T. Firefly, and Mrs. Teasdale.

        And in time of war never forget the immortal words of President Firefly :
        "And remember while you're out th

      • Today, the National Institute for Standards and Technology, the civilian agency of the US Government responsible for researching and making available data concerning the physical properties of substances including chemical elements, annouces the discontinued use of francium as the name of the 87th chemical element.

        Actually, the International Union of Pure and Applied Chemistry is the governing body on element names.. [iupac.org]

  • 2*10^19? (Score:3, Interesting)

    by Niahak ( 581661 ) <niahak.hotmail@com> on Friday May 23, 2003 @06:47PM (#6028211) Homepage
    That's a really long time. I mean, really long. The universe is considered to be 15 to 20 billion years by most who decide to actually guess. That means that, if the universe is 20 billion years old... and 1 g of Bi-209 was produced at the beginning of the universe, it would take another 1.999999998*10^19 years before half of the Bi-209 was left. I wonder if our universe will even reach that age, if the big bang 'cycle' theory holds to be true.

  • For the non-chemists/physisicists like me... (Score:3, Interesting)

    by Andy_R ( 114137 ) on Friday May 23, 2003 @07:08PM (#6028316) Homepage Journal
    Does 'stable' mean that decay hasn't been observed, or that it NEVER occurs?

    How does quantum mechanics apply to decay?

    Does an atom decay when a certain set of positions occur within it, and if so why can't the frequency that this would occur at be calculated?

    • Re:For the non-chemists/physisicists like me... (Score:5, Informative)

      by metamathica ( 607019 ) on Friday May 23, 2003 @10:19PM (#6029100)
      Disclaimer: my degree in physics qualifies me to paint a general picture here. Technical nitpicks are always welcome.


      In the article, it mentions that people actually have predicted this decay using theory. The nucleus is not completely understood, but the theory of basic decay phenomena is pretty complete.

      Any time you talk about the quanta of physics, you need to use quantum mechanics. The quanta are of course the so-called fundamental particles, including the proton, neutron and electron.

      The nucleus is held together by the strong force. This force must be very strong to keep the protons, whose like charge repels one another, very close together. The strong force only pulls over very short distances: if some nucleons get far enough, their electromagnetic repulsion will continue to push each other apart and they will be separated permanently.

      However, the particles in the nucleus don't have enough energy to get over the hump, so nuclei are stable. This is where quantum mechanics applies. Even if the hump is very tall, the nonlocality of quantum mechanics means that some particles can escape if the hump isn't very wide. Because they have a probabilistic spread in space, some of them can creep to the other side. When they get lucky like this, a nuclear decay occurs. The details of the nucleus determine how high the barrier and how wide the hump, both of which affect the probability of tunneling.

      In stable nuclei, particles are prohibited from escaping. In this case, it's not that the hump is too high, but that it's asymmetrical. If the nuclear force is strong enough compared to the energy of the nucleons, it can dig a deep well for the particles. In this case, having some possibility of getting past the hump doesn't really help: the area on the other side of the hump is prohibited regardless.

      One way to think of this process is to say that quantum mechanics would allow you to borrow the energy you need to jump over a fence as long as you fell back down on the other side, no matter how tall the fence.

      But you can't keep the borrowed energy, so you could never jump to the top of a roof, even if it were no taller than the wall you just jumped over.

      • "Disclaimer: my degree in physics qualifies me to paint a general picture here. Technical nitpicks are always welcome."

        I don't have a physics degree, but I'm pretty sure I understand that the Weak force can alter quark flavor, and that this constitutes a completely different decay mechanism from the one you described (not that the one you described is wrong). Am I confused?
        • I was completely amazed that someone modded me troll until I saw your comment! ;-) I have no complaints about honest dialog though. It may be too late for many others to read this, but at least you seem interested.

          You are right about the role of the weak force. The process you are thinking of is beta decay. In this process a neutron is converted into a proton, an electron and an antineutrino.

          Beta decay is detected by looking for beta particles, also known as electrons. This is another interesting p

      • But you can't keep the borrowed energy, so you could never jump to the top of a roof, even if it were no taller than the wall you just jumped over.

        Well, most of the time you can't keep the energy. Hawking Radiation is, however, a case where one of the particles does get to keep the borrowed energy.

        Hawking Radiation is covered will in this USA today article [usatoday.com].

        • Not really. He's talking about energy that's 'borrowed' from the vacuum. A different way of saying it is that the energy that a particle possesses isn't really an 'exact' quantity, but a distribution, and a small fraction of the time it's going to be actually have enough energy to leap the gap. Gaussians distributions are nice that way...

          Hawking radiation is where you're borrowing energy from the black hole, not the vaccuum. That's why you can 'keep' it - because it's actually just a very slow reaction of

  • First Nitpick Post! (Score:5, Informative)

    by fm6 ( 162816 ) on Friday May 23, 2003 @07:14PM (#6028346) Homepage Journal
    Bismuth-209 is not an element. Bismuth is the element -- Bismuth-209 is one of its isotopes. So the headline should read, "Bismuth no longer the heaviest element with a stable isotope". Except that's misleading too -- it sounds like they've found one even heavier. How about... oh, never mind.

    Incidentally, all elements have unstable isotopes. Bismuth's are pretty rare, but they do exist [jlab.org]!

    Bismuth obsessive will rejoice in the web site of the Bismuth Producers Association [bismuth.be].

    I prefer Tums, myself.

  • "Contained" is right! (Score:3, Interesting)

    by Markus Registrada ( 642224 ) on Friday May 23, 2003 @08:57PM (#6028791)
    Imagine my surprise at finding that Slashdot got something right: forii wrote that a "bottle of Pepto-Bismol contains one decay event" every 36 hours, and it does! Those alpha particles can't get through the glass.

    Not only that, he never said "it's" when he meant "its".

    My favorite element, by the way, is Osmium. It sublimates dreadfully toxic fumes from a solid state at room temperature, and nobody knows exactly what its specific gravity is, nor whether it or Iridium is the heaviest element.

    • here's a nice link. [webelements.com]
    • Imagine my surprise at finding that Slashdot got something right: forii wrote that a "bottle of Pepto-Bismol contains one decay event" every 36 hours, and it does! Those alpha particles can't get through the glass...

      ...whether it or Iridium is the heaviest element.

      Look, if you're going to sarcastic, I'm afraid that I have to nitpick your post. The question is whether osmium or iridium is the densest element, not the heavest.

      Quite right that the alphas can't get through the glass--they won't even trav

  • Proton decay (Score:5, Interesting)

    by reverseengineer ( 580922 ) on Saturday May 24, 2003 @12:30AM (#6029529)
    "Other kinds of decays such as protons from proton-rich nuclei could be studied by the same method but this will have to be proved!"

    This could prove to be the most important use of this technique, as most proposed Grand Unified Theories have interactions that can turn quarks into leptons, so that a proton would be expected to eventually decay into a positron and a meson. Unfortunately, this process has never been observed (well, only somewhat unfortunately, as high proton stability is definitely a Good Thing in most ways), and experiment and theory have thus set a lower bound on the lifetime of a proton of roughly 10^33 years, about 23 orders of magnitude greater than the estimated current age of the universe.

    As you can see, compared to the suggested lifetime of a proton, even Bi-209 seems unstable. The expected extreme rarity of a proton decay event, however, is somewhat balanced by the overwhelming abundance of protons in the universe.The "lifetime" for an individual proton is more like a life expectancy, an average figure- given a suitably large collection of protons, odds are good that at least one would decay in a reasonable timeframe. If you carefully watch 10^33 protons for a year, for example, and reality agrees with theory (big if), then it is likely (certainly not guaranteed though) you will see at least one decay event. Now, 10^33 may sound like a tremendous amount, but remember that each proton has a mass of only 1.67*10^-27 kilograms, so that 10^33 protons would have a mass of about 1,600 metric tons- a lot, but not outrageous.

    The real problem lies in that "carefully watching" part. So many other forms of radiation are much more prevalent, and so might mask the signature of proton decay. Cosmic rays, naturally occuring radioisotopes in places you'd never think to look, solar neutrinos, that sort of thing. Ah, why yes, this is one of those experiments they do in a salt mine and uses a gigantic tank of ultrapure water (your proton source). However, as of yet, no one has found concrete evidence for proton decay from one of these experiments. Go here [umich.edu] for a excellent site about a proton decay detector that ran in the 80s, and here [rl.ac.uk] for one currently in use.

    Perhaps this process will detect this very rare event, lending profound support to one of the many supersymmetric models out there. Unfortunately, if it does not detect proton decay, it will be much more difficult to say just what the result means, it being difficult to prove a negative and all.

    • Since nobody knows how long even simple elements will last, it is all a matter of degree. Some things decay fast, and some really really really slow, beyond our level of detection. If there is any element that is stable forever, we probably cannot test that since the Universe likely won't last forever according to current theories.

      Thus, "stable" is probably not really a Boolean thing.

  • somewhat OT isotope question (Score:4, Interesting)

    by frovingslosh ( 582462 ) on Saturday May 24, 2003 @01:15AM (#6029647)
    Since there are likely to be a number of people teading this that have good command of the topic, let me ask a question on isotopes. All through school I was taught that different isotopes of an element have the same chemical property. That information is still found in most articles on the subject. Yet I recently found a reference that Heavy Water was poisonous. Since there is no radiation danger, how can heavy water be poisonous if isotopes are chemically identical? What is going on here? And what are the indications of heavy water poisoning?

    • Re:somewhat OT isotope question (Score:4, Informative)

      by forii ( 49445 ) on Saturday May 24, 2003 @01:49AM (#6029740)
      Deuterium has different hydrogen bonding properties from H-1. This is a problem because a lot of biology (DNA, for instance) [uidaho.edu] relies on hydrogen bonding to hold things together correctly. If you started drinking a lot of D2O, the differently shaped molecules wouldn't fit together correctly and you would begin breaking down at the cellular level. If I recall correctly the effects are a lot like radiation poisoning.

      Another way that D2O differs from regular H2O. [webexhibits.org]
      • ...If you started drinking a lot of D2O, the differently shaped molecules wouldn't fit together correctly and you would begin breaking down at the cellular level...

        No! Deuterium behaves chemically exactly like hydrogen-1 (protium) in the compounds that it forms. The physical properties are slightly different (heavy water--deuterium oxide--is denser, and has higher freezing and boiling points. Heavy water ice cubes will sink in a glass of regular water.) Problems arise simply because of its added mass.

        • No! Deuterium behaves chemically exactly like hydrogen-1 (protium) in the compounds that it forms.

          Did I say anything of the sort? I said that the hydrogen bonding properties are different, and they are, because of the added mass. Hence the change in chemical kinetics that you describe.
          • It is slightly incorrect what you said. It is not about different shapes and probably also not about non-covalent, hydrogen bonds. (Acidic H+ get exchanged quickly).

            The problem is that some reaction have large "kinetic isotope effect", which usualy means - in case of deuterium-exchanged molecules - that heavy isotope carbon-deuterium bonds are metabolised at slower rate. Enzymatic reaction do this alot. Oxygen and carbon are other examples - although the effect is not as large as with hydrogen.

            Living orga
            • Just following up, the kinetic isotope effect is a consequence of differences in activation energies that are due to differences zero-point energies of stable and transition states. These differences in zero-point energies are a result of the effects of isotopic substitution.

              • Hmm I am a little confused about your post. From a classical calculation, I would believe that the chance of being at the transition state is independent of mass.

                p(x) = exp(-U(x)/k_BT))

                However the reaction rate is also proportional to the average velocity, which again is proportional to sqrt(m k_B T). Here m is some suitable mass, which will depend on the isotopes.

                • You are correct, except you need to take into account the idea of a zero point energy.

                  Specifically, what is U(x)?

                  In chemical kinetics U(x), or more properly (delta)U(x) is the energy difference between the stable state and the transition state. When a lighter isotope is substituted with a heavier isotope, the zero point vibrational energy levels all lower in energy. The same thing occurs for the transition state, except that the energy drops less in the transition state. This results in a higher effect
                  • Thanks for your answer. At body temperature I would guess that it was sufficient to use a classical calculation. If this is not true, then I would like to see a reference, so that I can learn :) Here is what I meant to write: In a classical approximation the energy is given by

                    E = U(x) + T(p)

                    Here x denotes positions of nuclei, whereas p denotes momenta of nuclei. The kinetic energy T(p) is dependent on masses. whereas U is the potential energy denotes the electronic ground state with fixed nuclei at posi

                    • Even at body temperature, the molecules are in their lowest vibrational states. Using the U(x) and T(p) terminology, you're right that U(x) will not be affected by changes in mass. However, T(p), specifically, the vibrational energy levels will be affected by the change in mass. Specifically, they will all drop, but the transition state (or saddle point) energies will drop less than those of the stable state, making the effective barrier along the reaction coordinate larger upon substitution. This large
    • It reacts a little slower than normal water, enough so that it throws some life processes off.

    • Heavy water toxicity (Score:2, Informative)

      by CERDIP ( 648784 )
      Heavy water poisoning of animals is caused by the D2O (heavy water) inhibiting cell division (mitosis). Bacteria growth rates are reduced, leading to problems in the GI tract, and bone marrow activity is reduced. So GI infections and enemia are symptoms. You would need to approach about from about a quarter to about a third of your body weight in D2O to achieve toxic levels. It would cost in the vicinity of $10,000 dollars and you would weight several pounds more when you died.
  • Are you the heaviest stable element?

    "None of your fricken bismuth!"
  • bismuth-209 decays into thallium-205

    Oh, no! The Pak [larryniven.org] will take over! ... eventually

  • looks like the pepto-bismol people already knew about this

    http://www.pepto-bismol.com/faqs.htm#8

    How do I read the expiration Date? Can I use Pepto-Bismol® past the expiration date?
    Expiration date example:
    EXP JL02C0041
    EXP = expires
    JL = indicates the month (July)
    02 = indicates the last digits of the year (2002)
    C0041 = indicates plant and production information

    If your Pepto-Bismol® has expired, please do not use it. The ingredients may not be stable after the expiration date.

    that would be E
    • People think expiration dates on medicines are like the dates you see on milk. When milk passes its expiration date, it is bad, period. I used to work in a generic pharmaceutical company under the domain of the FDA. After working in that lab, I lost all respect for expiration dates on pharmaceuticals. I almost never throw away medicine just because it's expired. This is what an expiration date really means:

      A sample is kept from each lot of a drug that's shipped. It's put in a box and kept in a closet somew
  • If proton decay occurs, then it is unlikey (albeit possible) that any atoms are truly stable.

  • I thought this was old news! (Score:3, Informative)

    by MillionthMonkey ( 240664 ) on Sunday May 25, 2003 @11:40PM (#6038754)
    My dad had a copy of Lange's Handbook of Chemistry that was published back in the sixties. I distinctly remember seeing that it listed the half life of Bi-209 as 2x10^23 years. That was only four orders of magnitude too long.

    In principle there are no stable nuclei heavier than iron 56. If you have a nucleus with atomic number A and atomic weight X, and you add up the binding energy of that nucleus, and compare it to the sum of the binding energies of an alpha particle and of a daughter nucleus with atomic number A-2 and atomic weight X-4, you will find that alpha decay is at least a little energetically favorable for many nuclei heavier than iron.

    If alpha decay is energetically favorable for a nucleus, then that nucleus is not stable. Alpha decay is a barrier tunneling process. If there's a potential energy drop on the other side of the barrier, the barrier will get tunneled through by an enterprising alpha particle eventually. It's just a matter of how long it will take- which is determined by the barrier width and the magnitude of the potential energy difference. The only reason many elements (iodine, gold, mercury, lead, etc.) are considered stable by human beings is that their decays have never been observed- because they are difficult to observe within human time scales. You might have to set up your experiment and wait for years, maybe centuries, before you see a decay. A bottle of mercury might contain two alpha decays per century. Is mercury stable? Not really, but for all practical purposes it is. It's all in the eye of the beholder.

    So it seems someone has caught bismuth in the act. Does this mean lead is now the heaviest stable nucleus? No, absolutely not. Lead has some advantages over bismuth- even numbers of neutrons and protons, etc. Pb-208 will definitely have a longer half life than Bi-209. Determining the half life of Pb 208 is going to be hard. But quantitative differences aside, the only real difference between lead and bismuth is that bismuth got caught!

  • I wonder how many laws and regulations will be triggered by the fact that Bismuth is now a "radioactive material".
  • since Bismuth decay rate is the slowest that has been observed, how do they know that other stable isotopes are not so stable? if they don't, then how do they claim that Bismuth is not the heaviest stable element. I guess, the only sure heaviest element would then turn out to be Hydrogen-1 isotope.
  • I have a few 'chunks' of it in my crystal/rock collection. I happen to think it's a cool looking element - continuous geometricly layered squares with oil-like coloring... I've had the pieces for ages but I haven't looked at the collection in at least a couple years. Guess I better check if it's still there!

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