Recently had to deal with radon in a basement, leading me to a fun side trek of learning about uranium decay (it has been a lot of years since chemistry classes).
When you hear about alpha decay of radioactive materials, that is the matter spitting off a highly ionized helium nucleus, freshly birthed into this world. That He nucleus rapidly steals electrons from matter, which is how it can be dangerous to human cells if ingested.
All of that helium underground is the result of alpha decay, and a single uranium-238 element will birth 8 helium atoms as it transitions through a series of metals and one gas (radon), then finally finding stability as Pb206. U235 will birth 7, becoming Pb207.
Anyways, found that fascinating. It's just happenstance that helium often gets blocked exiting the crust by the same sort of structures that block natural gas from escaping, and they are an odd-couple sharing little in common.
One other fun fact -- radon only has a half life of 3.8 days. Uranium becomes thorium becomes radium, then radon where it has an average 3.8 days to seep out of the Earth and into our basements, where it then becomes radioactive metals that attach to dust, get breathed in (or eaten) and present dangers. In the scale of things, crazy. Chemistry is fascinating.
> That He atom rapidly steals electrons from matter
tfa:
> Thanks to its filled outer electron shell, it is inert, and won’t react with other materials
The particle that is emitted from an alpha decay isn't actually called a He atom (I edited my root comment so this isn't misleading, apologies) -- I was being loose with terminology -- though it has the right number of protons and neutrons. It's called an alpha particle. Once it steals two electrons -- it carries a +2 charge and is extremely successfully at slicing electrons off of other molecules it comes across -- it is then considered the helium that we know and love, and is now stable with the properties we know.
And by stealing those electrons from other molecules it sets off other chemical reactions, which in things like DNA is highly suboptimal. This all generally happens at the birth of the He atom, presuming it isn't in deep space or something with no electrons to cleave from neighbours, and is only an instantaneous state.
> *particle that is emitted from an alpha decay isn't actually called a He atom”
“Because they are identical to helium nuclei, they are also sometimes written as He2+…” [1].
[1] https://en.wikipedia.org/wiki/Alpha_particle
You should really have posed that as a "I don't know anything about this so I'm confused" question.
He2+ is not a helium ion, which is very reactive. It’s not a helium atom, which is inert.
Because it rapidly steals electrons, it becomes inert quickly. Helium you find lying around will be inert. Helium that has just shot out from the radioactive decay of an unstable atom will not be inert.
I would imagine that an alpha particle would still be inert in the sense that it won't cause chemical reactions with other molecules.
Stealing electrons is a chemical reaction.