What happens to alpha particles after being emitted from a radioactive source? Do they ‘fall apart’?
Apparently they are highly ionizing which is what makes them very damaging in the small area they affect. If I remember chemistry properly, this means it causes atoms to ionize, releasing electrons. Do they join to the alpha particle to make helium?
Yes, in fact that is where most of the helium on Earth is belived to come from.
Two followup questions:
how rare is it for alpha emissions to actually ‘fuse’ with other atoms under ordinary earth conditions?
If I understand alpha emission correctly, it would be accompanied by the loss of two electrons from the electron cloud around the emitting nucleus… if Uranium (with 93 electrons) suddenly becomes Thorium, then it has to let go two of those electrons and just keep two. (I assume that these electrons do NOT become beta emissions, because those are electrons expelled from the nucleus when a neutron decays into a proton, or something like that.)
So what usually happens to those released electrons? Do they ever catch the alpha particle, or maybe find their way to the ionized matter (now looking for free electrons) and get captured there??
Also - after beta emission, a nucleus moves up one atomic number and needs to capture a free electron - until it has done that, it is an ion, right?
Never thought of this stuff before quite like this.
It would be rare for the exact same electrons to meet the alpha particle, but I’m sure it’s happened sometime.
Eventually the electrons and alpha particles will find partners, but it can take awhile (chemical-reaction-time speaking, of course.) In the meantime, there can be a whole bunch of reactions that take place due to ions running around, changing places, attracting other particles, etc. and this can really mess up living organisms.
I don’t know if there are different situations in which it takes longer for the charges to reach stability (for instance, being deposited in different places?) or not.
To address this, too, no, they don’t. Helium nuclei are not only stable, they’re one of the most stable of all nuclei, so not only will they not fall apart spontaneously, you’d have to work extra-hard to force one to fall apart. What they can do, however, is slow down. Once an alpha particle has slowed down, it’s just a helium ion, soon to become just a helium atom, which is about the most harmless thing you’ll find. Unfortunately, the process of slowing it down can do a fair bit of damage to whatever it is that does the slowing…