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copperastic
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Uranium compounds
Hi, I wasn't sure were this should go. What happens when a uranium compound decays? Would it turn into another element (down its decay chain) compound
or separate?
Thanks.
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TheChemiKid
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What isotrope of Uranium are you talking about? This is easily accessible information, and you should find it with no problem. This is very basic and
should be posted in beginnings, if posted at all.
When the police come
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Texium
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Quote: Originally posted by TheChemiKid  | | This is easily accessible information, and you should find it with no problem. This is very basic and should be posted in beginnings, if posted at
all. |
Is it really? I just did some Googling out of curiosity and couldn't find much very clear or general information on the subject. How about you share
some helpful information regarding the topic since you know enough about it to dismiss it as being so basic?
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IrC
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Is there something preventing either of you from going to google and entering "Uranium radioactive decay" in the search terms?
This thread belongs in the subset of beginnings titled "I insist you explain it I refuse to search". I'll even add two links from said search.
http://en.wikipedia.org/wiki/Uranium-238
http://en.wikipedia.org/wiki/Radioactive_decay
"Science is the belief in the ignorance of the experts" Richard Feynman
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Texium
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Well that information is very helpful if the question was simply about uranium decay, but that wasn't the question. Copperastic's question, was
regarding the effects of the decay on uranium containing compounds, not elemental uranium. Did you actually read the entire original post?
I did happen to find this, after additional search queries though. Not sure about the reliability of it, but it's closer to the question at hand.
http://physics.stackexchange.com/questions/8081/what-happens...
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Zephyr
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I do not think that there is a general rule for the decay of radioactive compounds, for instance, if the compound is compatible with the next element
on the decay chain, the compound may remain intact. However would the energy created by the radioactive decay, in some cases, split the compound?
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Texium
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That's what that thing that I found said:
"In general, radioactive decay is so energetic, that any chemical bonds/lattice forces are broken. What happens then is very complicated and not to be
answered by a simple scheme."
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Zephyr
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Where Is this information from?
Could you please cite your source?
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Texium
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It was this same thing which I posted earlier, sorry for the lack of clarity.
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Chemosynthesis
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My understanding is that this is not a simple matter at all; each case would have to be specific to the nuclide and ligand. Secondary complexes can
form due either to lability or degradation of parent to daughter nuclides, changing the LCAO's. Some decays, such as those of 99m Tc to Tc in
radiopharmaceuticals, change the activity of a radiopharmaceutical without affecting the chemistry.
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IrC
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"Did you actually read the entire original post?"
Not closely enough obviously I see your point. What he is asking is so very complex I doubt it is discussed often even in many otherwise good texts on
the subject of radioactive decay. Sorry copperastic you are actually asking a very good question which I think has a complex answer. One with many
possible outcomes.
I would think one starts with the decay chain and step by step works it out. Time would be important since it may take longer for the new element to
decay than it does for the newly 'homeless' elements to react in some way with elements in their surroundings. If you had an NO3 left over and Radon
floating away what would it do? What is around it with which it could react? How 'locked in' to the surrounding lattice are the leftover Oxygen and
pair of NO3's? This would require carefully going step by step from initial conditions, considering the chemical properties of every element in
question, including new arrivals. Bond energies of many elements needs to be considered as well as crystal lattice considerations.
Say you have Uranyl nitrate, UO2(NO3)2. I think trying to discover what is happening chemically as the uranium decays down the chain is very complex
and difficult. In many years of study I cannot recall any book I have read which covers this in depth. I get the feeling this is one of those
questions one could spend years studying (with great difficulty). Say doing chemical analysis of samples where even all gasses released while crushing
up the sample are carefully collected, measured and analyzed. A work both physically and theoretically so tedious it is no wonder I cannot even
suggest a good book on the subject.
"Science is the belief in the ignorance of the experts" Richard Feynman
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copperastic
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Maybe the uranium (lets say UO2) decays into lets say thallium then it becomes ThO2.
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Texium
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Well, uranium-238 first decays into thorium-234 (Th), not thallium (Tl), although thallium-210 is farther down the chain
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copperastic
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oh ok zts16.
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Zyklon-A
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Would this happen?
40KF -->beta radiation ~50%40Ca+ ~50%40CaF +electron capture ~10% 40Ar + gamma ray.
It's hard to balance this equation as 40K decays into different things in different proportions.
[Edited on 23-3-2014 by Zyklonb]
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Subcomputer
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It's amazing how complicated this can get, even with thought experiment pure conditions. A pure sample of Uranium-238 as UO2, degrading into
Thorium-234 as ThO2. Can I calcine it hard enough to draw that into the simulation? If I manage a crystal structure, what would be optimal to provide
strength to the molecules as the atoms split? If I allow other elements for secondary support elements, could they react before the Th and O radicals
had a chance to reintegrate?
Answering this would require (as IrC said) gathering incredibly detailed data, and LOTS of simulations.
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Pyrovus
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Perbromate was first prepared via the decay of radioactive selenate:
83SeO42- -> 83BrO4- + e-
Presumably the low energy of the decay allowed the ion to remain intact, though I don't know what the yield was.
Never accept that which can be changed.
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Steam
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Remember that chemical bonds occur because of electrons, not because of the nucleus. During decay, the number of electrons won't change (except for
electron capture). Theirfore the way a radioisotope decays will (for the most part) not effect the way it bonds.
That being said, exceptions can be made because the oxidation number of the species might change during decay, so decay compounds must be looked at in
a case by case basis.
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neptunium
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its a fascinating question that i have thought about years ago as well....When heavy elements from spent nuclear reactor are being discarded in
containers , a valve is added to release the helium gas due to alpha decay so it doesnt built preassure over time. Fluorine gas can be found trapped
in bubbles inside crystals due to slow natural radioactivity . so clearly electron capture allows elements to be naturaly separated (even F2!!!) it is
not un heard of to find many ions and free radicals (like NO3-) inside radioactive chemicals.
thermoluminescence dating is based on the fact that over time (milleniums..) electrical charges are building up in any given sample (mostly it is used
for clay and rock dating where the ions and free radicals dont have a long free travel track and have been heated ) unless the temperature gets high
enough (arround 500C) and things get shaffled and reorganized these ions will continue to build up due to natural radioactivity both from passing
ionizing radiations and left over from decayed atoms.
thats the general answer . on the case by case decay left over molecules and ions it is much more complicated .
lets not forget that for 1atom being observed we are talking about rare event in a rare situation over thousands of years (if not millions and
billions for U238) of stability in which nothing at all is happening...
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annaandherdad
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It might help to look at a simpler example of decay, say tritium->He3 plus electron (plus neutrino, but that escapes). Tritium is a gas. The
electron is emitted with some Kev of energy, much more than the binding energy, so it goes some distance away in the decayed atom, which is now a
He3+. Over time the gas will attain some degree of ionization, which is determined by the balance between ionization (due to decay) and
recombination. The former goes at a steady rate, while the rate of the latter increases with density, so a low density gas of tritium will achieve a
higher fraction of ionization in equilibrium than a dense gas.
If the tritium atom is part of a molecule, say HTO or T2O, then the molecule will behave as if one of the nuclei of hydrogen suddenly changed its
charge from +1 to +2. That's because the electron emitted by the beta decay escapes the atom at a velocity much greater than the orbital velocities
of the electrons left in the molecule. So, to find out what happens to the molecule itself, you have to solve the time-dependent Schr"odinger
equation for the electrons with an initial condition which is the wave function of the original (pre-decay) molecule, but with the charge of one
nucleus changed. In general, this is a linear combination of energy eigenstates of the new Hamiltonian, so there will be different outcomes with
different probabilities (branching ratios). For example, starting with HTO, you can end up with HO+ plus He3, or HO plus He3+, or other
possibilities.
Decay of radioactive nuclei in a solid is more complicated, of course, because, depending on the conductivity of the solid, the electrons (speaking of
beta decay) will not be able to move from their final locations after they lose all their kinetic energy.
alpha decay is similar, but the alpha particle won't travel as far as the electron in beta decay. gamma decay doesn't change the nucleus, but the
recoil of the nucleus could cause a dislocation of the atomic lattice site in a crystal.
Any other SF Bay chemists?
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annaandherdad
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Sorry, neptunium, you posted your reply while I was writing mine, and I didn't see it.
Any other SF Bay chemists?
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neptunium
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no problem,
which makes the whole study much more interesting to me !!
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neptunium
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not many people interested it seemed...
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annaandherdad
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Maybe your post was so definitive that no one has anything to add.
I'll add a few thoughts that this discussion makes me think about. You know in an insulator the charges can't move. If you take a block of
insulator, say glass, and expose it to a beam of charged particles that are able to penetrate into the material, you can deposit charges at random
locations distributed throughout the material. In this way the material picks up a net charge. I'm not sure, but it's possible this charged object
will collect electrons or ions on its surface in an attempt to remain overall neutral. In any case, in the interior the electric field builds up and
can get quite strong. If you keep adding charges, you get to a point where the material breaks down, and you get effectively sparks jumping inside
the material. These can make complex looking fractures inside the glass (supposing it's glass). I've seen pictures of this, but I don't remember
where, unfortunately.
If the insulator contains a radioactive substance, then the alpha or beta particles emitted will travel some distance from the decaying atoms and then
get stuck. This is different from the previous situation because charges of both signs are imbedded in the insulator. So the electric fields will
be much less than in the previous situation. However, it's still not an equilibrium situation, that is, if the charges were free to move they would
do so, so there is energy stored in the configuration. I don't know what this does to the insulator, if the amount of separated charge is allowed to
grow, but I know there has been talk of storing waste from nuclear reactors fused into some kind of glass. So if this is done, then such separated
charges must develop over time. If you something about this, why don't you tell me.
Any other SF Bay chemists?
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annaandherdad
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Maybe your post was so definitive that no one has anything to add.
I'll add a few thoughts that this discussion makes me think about. You know in an insulator the charges can't move. If you take a block of
insulator, say glass, and expose it to a beam of charged particles that are able to penetrate into the material, you can deposit charges at random
locations distributed throughout the material. In this way the material picks up a net charge. I'm not sure, but it's possible this charged object
will collect electrons or ions on its surface in an attempt to remain overall neutral. In any case, in the interior the electric field builds up and
can get quite strong. If you keep adding charges, you get to a point where the material breaks down, and you get effectively sparks jumping inside
the material. These can make complex looking fractures inside the glass (supposing it's glass). I've seen pictures of this, but I don't remember
where, unfortunately.
If the insulator contains a radioactive substance, then the alpha or beta particles emitted will travel some distance from the decaying atoms and then
get stuck. This is different from the previous situation because charges of both signs are imbedded in the insulator. So the electric fields will
be much less than in the previous situation. However, it's still not an equilibrium situation, that is, if the charges were free to move they would
do so, so there is energy stored in the configuration. I don't know what this does to the insulator, if the amount of separated charge is allowed to
grow, but I know there has been talk of storing waste from nuclear reactors fused into some kind of glass. So if this is done, then such separated
charges must develop over time. If you something about this, why don't you tell me.
Any other SF Bay chemists?
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