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Bismuth No Longer the Heaviest Stable Element
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."
[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.
You could've hired me.
Incidentally, all elements have unstable isotopes. Bismuth's are pretty rare, but they do exist!
Bismuth obsessive will rejoice in the web site of the Bismuth Producers Association.
I prefer Tums, myself.
Bismuth-209 is the most common isotope of bismuth (with its mean atomic mass being 208.98038), so it would be acceptable to say ' Bismuth No Longer the Heaviest Stable Element', according to webelements and The Jefferson Lab.
GAITHERSBURG, MD
22 May 2003
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.
"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."
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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.
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 for a excellent site about a proton decay detector that ran in the 80s, and here 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.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."