questions on atoms

[bethrook]

I am looking for a person knowledgeable in the structure of atoms; specifically the breakdown of radon and each element it breaks down into, and from. The number of protons, neutrons and electrons.  I have an email I would like to send to someone who can help me.  I perform radon testing and am making a coloring/storybook and that has led me to this.  Thank you. Beth Bruce. beth_rook@aol.com.  540-658-4663.

[ChrisbbSchmidt]

Hi Beth,

I don't do much chemistry anymore, but i do know there are lots of resources on the internet on Radon decay.

The most common isotope of Radon is Rn-222.  A good decay scheme is available on Wikipedia.

Perhaps another chemist can provide you with more information.

[bethrook]

Thank you, i have researched online and am hoping to get some specific information.

[ChrisbbSchmidt]

What sort of specific information are you looking for?

[bethrook]

Basically the breakdown of each atom in the series, the number of protons, neutrons, and electrons.  I am not a science or math person or a teacher.

This all started because I do radon testing and now I am branching out. I am making a children's coloring book and storybook that I hope will be entertaining and educational.  Can you refer me to an expert?  I need someone to review my project when I am done.

First, question on Beta decay-With Beta decay the neutron count goes down by 1; a neutron transforms into a proton and electron.  The resulting proton stays in the nucleus increasing the proton count by 1.  The electron is expelled;   Where does that electron go?  Does it leave the atom entirely?  Also,  do the other electrons stay with the atom still?

Do I need to make any corrections?  So far these are my notes:

Radon 222

86 protons

136 neutrons

86 electrons

Alpha decay, emits 2 protons and 2 neutrons.

Becomes Polonium 218.

Polonium 218

84 protons

134 neutrons

86 electrons?

Alpha decay, emits 2 protons and 2 neutrons.

Becomes Lead 214.

Lead 214

82 protons

132 neutrons

86 electrons?

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

Becomes Bismuth 214

Bismuth 214

83 protons

131 neutrons

86 electrons?

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

Becomes Polonium 214

Polonium 214

84 protons?

130 neutrons?

86 electrons?

Alpha decay, emits 2 protons and 2 neutrons.

Becomes Lead 210

Lead 210

82 protons

128 neutrons

86 electrons?

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

Becomes Bismuth 210

Bismuth 210

83 protons

127 neutrons

86 electrons?

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

Becomes Polonium 210

Polonium 210

84 protons

126 neutrons

86 electrons?

Alpha decay, emits 2 protons and 2 neutrons.

Becomes Lead 206.

Lead 206

82 protons

124 neutrons

86 electrons?

Stable, the end.

Question on Alpha particles; they supposedly plate out; what does that mean exactly?  They hit the wall and do they disappear?

(Makes me wonder; the Lead 206 is in the radon which is floating in the air.  Does the lead keep floating up into the atmosphere also, and if it hits a wall?)

After this I will start over from uranium and work my way up to radon gas.

I am noticing in science one question leads to another...

[ChrisbbSchmidt]

Hi Beth,

A couple things -

Beta emission in this case is the expulsion of an electron particle from the nucleus. 

The electron counts you are tracking are irrelevant to the identity of the atoms being created. It is the proton and the neutron count that distinguishes one atom from another. When we talk about nuclear decay, we don't usually worry about the number of electrons around the nucleus. The number of electrons can impact its reactivity with other atoms, i.e. the chemistry it has, but when it reacts in this way, the nucleus does not change its number of protons and neutrons.  The arrangement of electrons is based on some complex mathmatical probabilities and an atom may lose or gain electrons to add stability to the electron configuration.

I suspect that lead plates, i.e, deposits upon some surface instead of remaining in the air.

[mbdowell]

Hi Beth,

I agree with everything Christine said, but I think that you have a question still out there: we started with 86 electrons, so what happened to them?  Let's do it comic book style; students learn well from that. In Panel 1 we have a Rn nucleus lower left and a big cloud of gray or silver electrons everywhere else. But that nucleus is unstable! It's rippling. Maybe that looks red and green in the comics universe but the nucleus has vibrational modes in the liquid-drop model of nuclei, and maybe by Panel 3 it's separated into a 218Po84 nucleus and an alpha particle, a 4He2 nucleus, both still inside the electron cloud. They are both positively charged and they are going to repel each other, and in any case the nuclear decay gave off a lot of energy--5.6 MeV (million electron volts), and that becomes kinetic energy moving the particles away from each other. If you look it up in the nuclear decay scheme in the Chart of the Nuclides, aka Table of the Isotopes, approximately 5 MeV goes with the alpha particle. I'm imagining a panel in which the Po nucleus is still surrounded by the big electron cloud and the positively charged alpha particle is starting to move out through the cloud at 4200 km/sec (5 MeV = 1/2 mv2) and someone says (either nucleus or an observer) "Wait! What about the electrons?!"

[mbdowell]

And then, Beth, the alpha particle says "I'm taking 2 of them! I'm a helium nucleus after all. I gain 50 eV for the first electron and 25 eV for the second (which you look up in a table of Ionization Potentials) so you are paying me energy to take them away!" The answer to your question, "86 electrons every time?" is, every time an alpha particle (helium nucleus) is emitted, it takes two electrons with it as it passes through the cloud of electrons that surrounded its former parent atom. The other daughter atom, Po in this case, now has 84 atoms, just the amount it needs to be a neutral atom. Since there is only one parent or daughter atom in any panel, we don't have to consider whether it's a gas or a solid and that should not matter.  When your atom decays by beta emission and emits an electron, the nuclear charge increases by +1. If you could capture that electron the new daughter atom would remain neutral. Certainly there is an empty space in the electron orbitals, and you would give off 5 or 10 eV if you filled the orbital; it would be energetically favorable. But the betas being emitted have more than 1 MeV of kinetic energy, they probably just keep going and leave positive ions behind. It's energetically favorable to turn any of the new positive ions in your decay chain into  neutral atoms; they just need to find an electron that has much less kinetic energy than the beta. If the ion landed on a metal or glass surface, it could probably pick up an electron. I'm glad that you asked the question the way you did-- artists always worry about important stuff.

[bethrook]

This is fascinating but I don't understand much of what you just said.  It sounds like you all are saying that the electrons change a lot.  So then how did radon 222 come to have 86 electrons in the first place?  I drew my radon atom with electrons in specific orbits around it.  In fact I believe I found that orbit information and it was specific.  I actually had to re-draw it because I didn't do that to begin with.  If I leave each decay product in the chain with with 86 electrons is it still correct then?  How much can these number of electrons fluctuate, like what is a range? 

[bethrook]

I just read again; it looks like you said when the alpha particle is emitted it takes 2 electrons with it?  So every time it's alpha I can subtract 2 electrons? 

and for beta, these are my notes: With Beta decay the neutron count goes down by 1; a neutron transforms into a proton and electron.  The resulting proton stays in the nucleus increasing the proton count by 1.  The electron is expelled. 

So based on what I think  you said, that electron goes out of atom most likely?  So the number of electrons doesn't change then?

So I should remake my atoms so that every time there is alpha it loses 2 electrons that the alpha takes with it?  (ok so 2 protons, 2 neutrons and 2 electrons-what is that called, is that now Helium?)

Thank you.