Sciencemadness Discussion Board

Where do radioisotopes decay elements go ?

metalresearcher - 3-11-2010 at 09:53

Many radioisotopes occur in nature, tghe most common are U-238 and K-40 (1 atom of every 8600 K atoms in nature). They disintegrate into other elements leaving alpha or beta particles behind.
While yoou read this text, thousands of potassium atoms in your body disintegrate into Ca-40 and Ar-40. But the K in your body is not as a free metal, but combined such as KCl or K2CO3 or as a K+ cation. What I wonder when the K in KCl falls apart, the Ar cannot combine again with the Cl- and the Ca requires two Cl- ions. My question: what happens to these 'broken' compounds ?


Random - 3-11-2010 at 10:13

Maybe Cl ion reacts with anything that is close to it.

I also wonder what could happen if I would somehow remove Na+ ions in inert atmosphere from Cl ions. Cl- ions would give electrons to what?

psychokinetic - 3-11-2010 at 11:42

Nothing, you'd have free radicals, no?
Then cosmetic companies use this information to make up some pretend science to make you buy their product to fix them.

12AX7 - 3-11-2010 at 13:39

Charge balance is neutral because the released electron sticks to something, or the positron annihilates.

In solution (like the K+ in your body), electrons are all around, so it doesn't really matter what happens, it remains neutral in the end. The only difference is that the charge may be locally unbalanced, i.e., the electron ends up several mm from its initial position! As long as the total number is small (don't go stand in a nuclear reactor..), the charge will remain small in comparison to the number of electrons around, and the difference will ultimately neutralize itself (positive and negative charges attract).

You do indeed get strange compounds when you start switching ions around. Most compounds become amorphous, or disintegrate, although this is primarily due to the destructive action of the radiation itself, rather than transmutation of the elements.

For instance, the destructive capacity of a fresh beta particle is many times that of the electron itself. A free electron might have a few eV of energy associated with it, corresponding to the electron affinity of the compounds it is attracted to (which will generally result in a radical or anion, when it combines). A beta particle might have 1,000,000 eV associated with it, capable of breaking thousands of bonds, forming thousands more radicals. Beta radiation doesn't carry much momentum (the electron is light), but it does carry some, and is capable of knocking atoms directly out of place.

Neutron radiation is the most destructive, because the particle is more massive, and is capable of transmuting elements directly. For instance, graphite will absorb the momentum from neutrons, knocking carbon atoms out of place. Some of this energy is stored as Wigner energy. This energy can be released by annealing the graphite, which allows the atoms to fall back into their natural position. In addition, some neutrons are absorbed by the nucleus, resuting in C13 (which is stable) and C14 (which is intensely radioactive). Decay of C14, or further bombardment, results in nitrogen (C13 --> N14 by beta decay), which will remain trapped in the crystal as an impurity, until diffusion causes it to move around. (If two N impurities meet, they could form N2 gas, which would diffuse out.)

Incidentially, graphite blocks blown out of the Chernobyl reactor remained hot to the touch(!) for hours after the incident (or was it days?).

Tim

DDTea - 3-11-2010 at 20:37

DNA can be mutated by such decays and exposure to UV radiation. DNA is neat, though, because it has several repair mechanisms with which to deal with these things. So in the greater scheme of things, it doesn't make a huge difference.

merrlin - 4-11-2010 at 00:12

Quote: Originally posted by DDTea  
DNA can be mutated by such decays and exposure to UV radiation. DNA is neat, though, because it has several repair mechanisms with which to deal with these things. So in the greater scheme of things, it doesn't make a huge difference.



Increased carbon-14 concentration has been shown to increase lethal mutations in drosophila and mice. Algae cultures grown with extremely high concentrations of carbon-14 (used to produce tracer compounds) have a limited lifetime. As stated by Tim, beta decay can be quite energetic. There is a considerable amount of literature on the mutagenic effects of tritium and carbon-14. Isaac Asimov once estimated that a 70kg human body experiences about six carbon-14 beta decay events per second in its DNA alone. Peak energy for carbon-14 decay is 156,000 electron-volts.