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Topic: Valency change in a decay series: What happens to the other ion?  (Read 8039 times)

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Offline curiouscat

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Say element X decays to Y. If the initial X was present as a compound, say an oxide, XO (i.e. assume X is usually divalent ) but Y has a different dominant valency (say trivalent, so Y2O3 would be a common oxide).

In this case what happens? Does XO still lead to Y2O3? If so, what happens to the oxygen deficit.

Is there a general way to analyse such transitions?

Somehow  I always only paid attention to the radionucleotide but never gave much thought to the counterion.

Offline Arkcon

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #1 on: May 24, 2014, 12:27:52 PM »
A similar topic came up in another thread, that I can't find right now.  Briefly, nuclear radiation used to be (and probably sometimes still is) called ionizing radiation.  So emission, in addition to release of beta or alpha particles, the product nuclei may exist a ionized species, until they can neutralize their charge.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Borek

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Offline curiouscat

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #3 on: May 24, 2014, 03:30:32 PM »
http://www.chemicalforums.com/index.php?topic=74893.0

Thanks. So basically, molecular identity post decay would be in itself highly variable & broken to say anything more about the compound formed post decay? Is that the take home message?

Offline Borek

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #4 on: May 24, 2014, 03:33:46 PM »
That's my understanding. Don't treat me as an oracle.

A lot depends on the decay type, but if memory serves me well during fusion of uranium produced light nuclei travel even micrometers from the place they were produced.
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Offline curiouscat

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #5 on: May 24, 2014, 03:39:48 PM »
This Wikipedia bit was what got me thinking:

"Most commercial 99Mo/99mTc generators use column chromatography, in which 99Mo in the form of molybdate, MoO42- is adsorbed onto acid alumina (Al2O3). When the Mo-99 decays it forms pertechnetate TcO4-, which, because of its single charge, is less tightly bound to the alumina. Pouring normal saline solution through the column of immobilized 99Mo elutes the soluble 99mTc, resulting in a saline solution containing the 99mTc as the pertechnetate, with sodium as the counterbalancing cation."

So apparently at least in some practical examples of decay people are counting on the end compound being of a specific identity.

Wonder how much of a kick this particular decay gives.

Offline Borek

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #6 on: May 24, 2014, 04:13:44 PM »
β-, wikipedia claims 142 keV.
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Offline Enthalpy

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #7 on: May 25, 2014, 06:45:55 PM »
In a beta decay, the electron and the antineutrino get most energy, leaving a tiny fraction to the nucleus. Additionally, beta decays tend to have less energy (500keV, 1MeV) than alpha (5MeV).

In the alpha decay, the helion gets the energy, and gives a big kick to the remaining nucleus, because an alpha is much heavier than an electron.

A fission is much worse, with a typical energy of 200MeV and fragments weighing like 80 and 140 nucleons.

Then you have the charge unbalance at the remaining atom (or rather ion) which shakes the molecule. A possible scenario is that the fragments recombine to a molecule, often similar to the initial one because these are the available bricks.

Offline curiouscat

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #8 on: May 26, 2014, 12:37:33 AM »
It'd be interesting to see if one could measure a spike in free Oxygen evolution.

Would need a very careful experiment.

Offline Enthalpy

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #9 on: May 26, 2014, 11:17:38 AM »
Alas, the beta will create oxygen, hydrogen, peroxide and more through radiolysis. This risks to hide the possible release of oxygen by a perturbated molybdate or pertechnate, i case this was your thought.

You know, the nuclear reactor buildings that went bang because of hydrogen produced at the spent fuel (essentially beta minus emitters) pool... One more accident scenario for which the author was laughed at before it happened. Though I have my doubts that this destroyed #4, since the building had already a hole, and because my estimates for hydrogen production fall low.

Offline curiouscat

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Re: Valency change in a decay series: What happens to the other ion?
« Reply #10 on: May 26, 2014, 11:46:59 AM »
Alas, the beta will create oxygen, hydrogen, peroxide and more through radiolysis.

In a non-aq. environment? How will a beta make, say, peroxide?


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