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Author: Subject: Uranium compounds
neptunium
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[*] posted on 3-4-2014 at 11:24


i remember seen a video (cant remember where..) they put a certain type of transparen glass bottle into a strong source of Co 60 or inside a running nuclear reactor and left it there a few hours .
When it came out it was completly opake and to get it transparent again it was put into an oven to heat up...
this was described as the charged particles generated inside of it were trapped (as you pointed out) and were absorbing photons whereas the clear looking glass had no (or very little) isolated charges..
if i find the link to the video i`ll post it here...
but it goes along what you were just saying..
So to go back to the original question, isolated charged and ions or even whole group (like SO4--) are likely inside radioactive chemicals and even common.




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[*] posted on 3-4-2014 at 11:57


Quote: Originally posted by annaandherdad  
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.
...
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.

You're probably thinking of Lichtenburg Figures (the first image on that page). I have one on my desk right now! I bought mine from these guys - they have lots of different styles and all are beautiful.
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annaandherdad
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[*] posted on 4-4-2014 at 10:59


Yes, that's it exactly! Thanks for the link, and sorry about the double post.



Any other SF Bay chemists?
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[*] posted on 13-9-2014 at 15:13


I suspect in many alpha and beta decays the recoil on the nucleus from emitting a very energetic particle is enough to break a chemical bond, so it is then not only a matter of working out what happens electronically.



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[*] posted on 13-9-2014 at 18:00


Quote: Originally posted by phlogiston  
I suspect in many alpha and beta decays the recoil on the nucleus from emitting a very energetic particle is enough to break a chemical bond, so it is then not only a matter of working out what happens electronically.


A simple physics BOTE calculation. The mass ratio between and alpha particle and the Th-234 emitting atom is (formerly a U-238 pre-emission atom) is about 1:60 (1:58.5 more precisely).

Conservation of momentum requires that mv (alpha) = mv (atom). Since the alpha is 60 times lighter, it must travel 60 times faster than the atom post recoil or momenta to equal.

Kinetic energy is KE= (mv^2)/2 so the atom/alpha kinetic energy ratio is:
(60*1^2)/(1*60^2) = 1/60

Thus if the total decay energy is 4269.7 keV, then about 1/60 of that would end up as kinetic energy of the atom, or about 70 keV.

Since molecular bond energies are several eV the recoil energy of the atom will not only disrupt those bonds, it will cause the atom to the ejected into another part of the lattice structure. Additionally the alpha particle will zip along disrupting chemical bonds as it goes until stopped., whereupon it become an alien embedded helium atom.

So alpha decay at least completely destroys any chemical bonding that the parent atom participated in, and then some.

Nuclear decay is a process that drives the evolution of uranium minerals in noticeable ways.

For beta decay the ratio is more like 400,000:1; that Th-234 decays into U-234 with a decay energy of 270 keV, so the kinetic energy is only ~0.6 eV. The electron shell configuration changes though (different element) so does to associated ion states available. U has a +6 state, Th does not, so the chemical compound can still change especially with the excitation energy of 0.6 eV to help things along.
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