In the standard discussion of alpha radiation they give examples such as a radium atom decaying into a radon atom with the emission of an alpha particle or a uranium atom decaying into a thorium atom and an alpha particle. However, I don’t remember any discussion of what happens to the two extra electrons. The radium atom starts out with 88 protons and 88 electrons, emits the alpha particle with its 2 protons and 2 neutrons, and ends up with a radon atom with 86 protons. There is no mention of any beta radiation (electrons). Do we end up with a radon nucleus with 86 protons surrounded by 88 electrons? Surely this wouldn’t last very long. What happens to the 2 extra electrons?
I was stumped by this as well because ive studied Alpha radiation but couldn’t remember the answer
Apparently those 2 electrons are lumped into the helius nucleus
That’s not a good way to describe it. The original description is nuclear not chemical, it ignores the electrons. They certainly aren’t in the helium nucleus. Eventually that helium nucleus will slow down and grab two electrons from someplace becoming a helium atom.
Stupid me, actually you are quite right. I was writing it in my head as a chemical equation rather than a nuclear equation
Helium atom at bar: I’ve lost my electrons!
Random bar patron: Are you sure?
Helium atom: Yes, I’m positive.
that joke is rad.
Why doesn’t the alpha particle just take the two electrons along with it, to become a full-fledged Helium atom?
- The electrons were quite some distance from the nucleus of the uranium, the alpha particle didn’t own any electrons when it was born, and the alpha particle goes flying outward through the electrons at quite a rate… (particle properties…I assume the alpha particle doesnt have wave properties…)
- Probably significant repulsion comes from the electric force…
The electrons will then leave the resulting heavy (eg Thorium ) atom, but only at normal energies, only at the normal energy of the conductive electrons in metals…it just becomes static electricity…
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The radon atom simply becomes a negative ion until it can lose the electrons somewhere.
The electricity can be measured and in deed there is a electric power source design that makes use of this static electricity generated by radiation…
RTGs do not generate power that way, though, if that is what you mean, they use thermocouples to turn the heat into electricity.
Its a two fer!
Because, due to the speed of the alpha particle, from the frame of the alpha particle, the loose electrons will have a much higher energy than the ionization energies of helium.
We do end up with a negatively charged ion. Those extra two electrons will be held quite weakly and likely to be given up at the first instance.
You mention beta decay. Keep in mind that the emission of an electron during beta decay is also a nuclear process. A neutron decays into a proton, electron, and an antineutrino. The proton stays in the nucleus and the electron is emitted at high energies. This kind of electron emission is very different from electron transfer from a negatively charged ion, both in terms of where the electron originates from and the relative energies involved.
Surely in the case mentioned in the OP there is no chance of a negatively-charged ion being formed?
Isilder isn’t referring to RTGs. There are actually devices that use the charge movement due to radioactive decay to provide useful power-- Only a trickle of it, but it lasts a very long time and is very safe and reliable. I’ve more often seen them based on beta radiation, but there’s no reason in principle that alpha couldn’t be used, too. Some pacemakers are powered this way.