Radon

Definition

Radon (chemical symbol Rn, ²²²Rn) is a chemically nonreactive noble gas, and a radioactive chemical element with an atomic number of 86 (in the periodic table) and an atomic weight of 222. It is one of the products of spontaneous uranium decomposition (²³⁸U), and directly issues from radium alpha decay (the name radon is from radium, ²²⁶Ra). Uranium is a natural trace constituent of some types of rocks and soils in the Earth's crust. Like radium, radon is also an alpha particle emitter, and has a half-life of 3.85 days. Humans are exposed to radon and its decay products, called radon daughters , either professionally in underground mines, or unprofessionally from the ground under and around buildings, from ground water, or from some building construction materials. From the ground, radon gas diffuses through cracks or holes and beside pipes, easily penetrating basements, ground floors,...