I've searched the web madly, but I can't find a thorough explanation of alpha decay. When a nucleus is unstable, it emits a clump of 2 neutrons and 2 protons, and this is called an alpha particle. Is this right? As for the 2nd question. Why are alpha particles deadly if ingested? After all, the alpha particle is in the form of a helium nucleus, and if helium is inhaled it will just make your voice high pitched. Does anybody have an answer? Any help would be greatly appreciated.