What type of emitter is 222Rn?

Radon-222 (222Rn) is classified as an alpha emitter because it decays by emitting alpha particles. An alpha particle consists of two protons and two neutrons, which is essentially the nucleus of a helium atom. This type of radiation is characterized by its relatively large mass and charge, making it less penetrating compared to beta and gamma emissions. Alpha particles can be stopped by a sheet of paper or even the outer layer of human skin, but they can cause significant biological damage if inhaled or ingested, which is particularly relevant in the contexts of lung cancer risk associated with radon exposure in homes.

In contrast, beta emitters release beta particles, which are high-energy, high-speed electrons or positrons. Gamma emitters release gamma photons, which are very penetrating electromagnetic radiation. Electron capture, another process associated with some radionuclides, involves the capture of an electron by the nucleus, leading to different decay pathways and emissions. However, the defining characteristic of radon-222 is its emission of alpha particles during decay, thereby affirming its classification as an alpha emitter.