questions on atoms

[ChrisbbSchmidt]

This is a great discussion.

One thing you have to remember is that electrons are not really attached to the atoms. They are attracted by their negative charge to the positive charge of the nucleus. So when the alpha particle leaves (and it has a +2 charge), it is less likely that the nucleas from which it originated has enough charge to hold an extra 2 electrons.  When I studied radio and nuclear chemistry, we didn't really worry about where the electrons went. They could go with the alpha particle, although it has lots of energy and may be moving 'fast' enough that the electrons don't find it before it leaves. But the electrons do leave somehow. They could attach themselves to a water molecule or some other electrophilic molecule.

I do remember that although the nuclear configuration of a Helium and an alpha particle are the same, nuclear chemists (back in the day) used alpha to indicate that this particle originated from a nuclear reaction.  I'm not sure how important that is to your audience, but I suspect that is what a purist would say.

As for beta emission -- the actually emission is essentially a high-energy electron originating from the nucleus.  It does leave the molecule.

Electrons don't have to be associated with a specific atom, they can move around and can jump from atom to atom. That is the basis for many chemical (not nuclear) reactions.

Michael Dowell​ - what do you think?

[mbdowell]

I'm still agreeing with all you said, Christine, and about to back off one of my statements. The discussion is getting better and better because Beth wants to do this in comics/graphic novel form, and the story has to be clear enough that she can illustrate it.

If Beth can illustrate just the charges on the nucleus, just take away the alpha particle with its +2 charges and 4 mass units. It's true. The nucleus that's left is the " daughter" nucleus in your decay chain.

If you need to show what happens to the electrons when the alpha decay occurs, take 2 away from the cloud around the daughter atom and show the daughter as a neutral atom. Don't illustrate anything else that happens; it's complicated and I think, subject to correction, that you end up with a neutral daughter in most cases within about a microsecond. As Christine tactfully explained, the alpha particles may want those 2 electrons to become a neutral He but they are moving too fast-- when radium disintegrates, Rutherford was able to make a beam of alphas and bend it with electrically charged plates, so they get  several cm away from the daughter nucleus before they pick up electrons. If you had a neutral daughter atom that had not just received a lot of energy from the nuclear decay and you "offered" it an electron, it would give up energy to get the electron (the "electron affinity" of neutral Po is 1.9 eV and of Pb is 0.4 eV, so they would give you that for the first electron) and become an ion. But the nuclei have just been given about a million eV from the decay-- the rest goes away with the alphas-- and they are trying to give that away so they probably can't hold on to the electrons.  I doubt there's room in the comics universe to tell all that, so I'd just take away 2 electrons.

What about beta decay? As Christine says, the beta is an electron with more than a million eV; it's moving fast and gets away. You now have a daughter nucleus with one more positive charge and the original electron cloud, so you have a positive ion. If you don't show the electron cloud, only the nucleus, you are good. If you want to show the electron cloud anyway, I'd just show the beta electron going away and a +1 daughter ion.

Look, it has to be a compelling story and it can't tell anything untrue. But first it has to be pictorially compelling. If what I'm suggesting gets in the way of that, let's back off until we find the simple and true story that wants to be on Beth's page.       

[bethrook]

Thank you for your answers. So far what I am doing is pretty simple.  I also heard back from another person I contacted lately and this is the answer he gave me, his answers in red if it comes out.  Blue are my questions. He also recommended I consult a physicist with work:

Question: Why are the electron shells with the exact number of electrons in each shell available for the radon and some other atoms, but not others?  Like you see Polonium 209 but not 218.  Which I believe that means Polonium 209 has 125 neutrons?  Is there something different about the particular atoms chosen to be on the chart?

http://education.jlab.org/itselemental/ele086.html

Radon 222           Electrons per Shell 2, 8, 18, 32, 18, 8

86 protons

136 neutrons

86 electrons

Alpha decay, emits 2 protons and 2 neutrons.  (Does it takes 2 electrons with it? which 2 electrons?  which orbit or shell? Does it matter?)

Becomes Polonium 218. The resulting atom has two fewer electrons than it began with, as well as two fewer protons and two fewer neutrons, the alpha particle is the combination of those two protons and two neutrons.  The two electrons may remain with the alpha particle, but again they don’t matter a bit.  (really? Everyone keeps saying that electrons don’t matter).

Question:  Does that mean an alpha particle has 2 protons, 2 neutrons, and zero, 1 or 2 electrons? Is this alpha particle an element of it’s own or just a particle?

Generally atoms are found neutral, that is, the same number of electrons as there are protons in the nucleus.  So it’s easy to determine the number of electrons.

Polonium 218

84 protons

134 neutrons

84 electrons

Alpha decay, emits 2 protons and 2 neutrons.  (Does it take 2 electrons with it, which 2 electrons?  which orbit or shell?)

Becomes Lead 214.

Lead 214

82 protons

132 neutrons

82 electrons?

Beta decay, a neutron becomes a proton and electron and the electron goes way

Becomes Bismuth 214

Bismuth 214

83 protons

131 neutrons

82 electrons? 83

Beta decay, a neutron becomes a proton and electron and the electron goes away

Becomes Polonium 214

Polonium 214

84 protons?

130 neutrons?

82 electrons? 82

Alpha decay, emits 2 protons and 2 neutrons.  (Takes 2 electrons with it?  Which 2?—could be any 2, but expect it to be those on the outer shell as they are held most lightly.)

Becomes Lead 210

Lead 210

82 protons

128 neutrons

80 electrons?  (I assume 82 now.)

Beta decay, a neutron becomes a proton and electron and the electron goes away that’s right.

Becomes Bismuth 210

Bismuth 210

83 protons

127 neutrons

80 electrons? Nope, 83

Beta decay, a neutron becomes a proton and an electron and the electron goes away

Becomes Polonium 210

Polonium 210

84 protons

126 neutrons

80 electrons? 84

Alpha decay, emits 2 protons and 2 neutrons.  (Takes 2 electrons with it?  which 2?)

Becomes Lead 206.

Lead 206

82 protons

124 neutrons

78 electrons? Nope, 82.

And this is just my curiosity, it seems the more I know the more questions I have; Does the lead 206 float away, fall to the ground?  Would there actually be a visible source of lead 206 someplace?

I don't have the means to make an actual cartoon, I will be making drawings to color and hope to put them in a coloring book soon that I will sell on my website and may hand out for marketing.  However you gave me an idea above to make an electron shooting out, and also I had thought to make an alpha particle.  So far my atoms are pretty simple, made with Powerpoint.  My character is Radon Rhonda, who is going to come out of a rock and float through the air, into a house, be breathed in and out, and she will escape through a radon mitigation pipe. So, not too technical at this point.  However I thought to make representations of the decay atoms as well, how she changes.  Realizing of course I have used color, but in real life I will point out she is invisible.Radon Rhonda

[bethrook]

I think one of you above did answer a question about the alpha particle, and I will re-read your answers again when I have a moment so that I can study what you are saying more.  I think what I gather is that they go through changes, but I am looking for the neutral atoms, like a stopping place before they start changing again?  Also the alpha particle is an alpha particle in relation to the process of what is happening, but it is also the element helium? Is +1 daughter ion the element that remains?  Like the Polonium 214 (and actually should that be 84 electrons?)

[mbdowell]

Hi Beth,

I do like Radon Rhonda. She's a cute way of getting the message across. Are you thinking of having her emit an alpha particle from time to time?

About the electrons: when an alpha leaves the nucleus, it doesn't have any electrons, it's a +2 particle and because radioactive decay gave it a lot of energy, it is moving fast.  It would like to gain 2 electrons and become a neutral helium atom. It will pay 75,000 eV for the second electron and more for the first, and that is almost always enough to ionize any neutral ion that it hits. Remember that in the radon business, you detect ionizing radiation-- this is it. In beta decay, the nucleus kicked out an electron. That's also a charged particle and it can trip your detector, maybe by colliding with one of its electrodes.

Remember also that when Radon Rhoda gave up her alpha particle, her daughter was Polonium and you said "+84 in the nucleus, are there still 86 electrons?" That would be Po-2. Well, Po is below O in the periodic table and we know that O likes 2 more electrons to fill its outer shell, so that could be. In fact, a neutral Po atom will give you 1.9 eV for the second electron and more for the first so it likes the -2 charge. Trouble is, now it has to go looking for a +2 ion or two +1 ions to combine with. Or, when the alpha particle left, it had enough kinetic energy that it could have knocked 2 electrons off Po-2 and left you with neutral Po. Every one of these outcomes is possible and happens some fraction of the time. You gain nothing by telling this messy part of the story.

But you might want to say that after the alphas and betas have left the old nucleus, all the electrons that were around it eventually find homes in neutral atoms, either the new daughter atom or by forming He atoms with alpha particles. It's short and it's true.

Finally, we have helium atoms and polonium atoms forming from Radon Rhoda in the gas phase. Does Po stay as a gas? How about the other decay daughters? Well, Rn is a noble gas and so is He; they don't combine with anything. But Po is a solid that melts at 254C and boils at 962C, and Bi is a metal and so is Pb so all of those want to do something else. How do they get out of the gas phase after they are born? Since we have simplified the story and present them as atoms, what would each kind of atom do? Po has the same electronic structure as O. If you had a free O atom, it would be pretty reactive with its neighbors. It could form peroxide with water vapor or react with the walls of the container. Bi might react with water or oxygen  or stick to the walls, and same with lead. A really short answer is "we make new atoms and they find chemistry to do", but that's another story.

[DonivanPorterfie]

Beth, I would second the observations of Christine and Michael that typically while discussing radioactive decay it is common practice to ignore the orbital electrons in the associated nuclear transformation.  While the orbital electrons around the nucleus are typically of preeminent interest to chemists (since they control chemical behavior and reactions) they are typically unimportant to most nuclear transformations.

But to complicate matters in the relatively long period between nuclear transformations those same orbital electrons can influence the behavior of the atom.  So for example based on its orbital electron structure radon is a noble gas and thus can exhibit a considerable tendency to diffuse through air and soil.  Based on having a different orbital electron structure the polonium decay product of radon is not a noble gas and will be much more limited in its travels.  That limited ability to travel gives rise to its tendency - and that of other radon decay products - to “plate out”.

The overall orbital electron structure of an element is dependent on the number of protons.  So Rn-222 and Rn-220 will have the same overall orbital electron structure given they both have 86 protons in the nucleus.  So given that similar orbital electron structure both Rn-222 and Rn-220 are noble gases and as noted above have the same tendency to diffuse through air and soil.  However, since Rn-220 has a much shorter half-life than Rn-222 it will effectively not get as far before it decays.  So that is why most discussions of the dangers of radon are focused on Rn-222.