What is Radon atom?

     

Radon is a chemical element with the symbol Rn and atomic number 86.  It is a radioactive, colorless, odorless, tasteless noble gas.  It occurs naturally in minute radioactive decay chains through which thorium and uranium slowly decay into lead and various other short-lived radioactive elements.  Radon itself is the immediate decay product of radium.  Its most stable isotope, 222Rn, has a half-life of only 3.8 days, making it one of the rarest elements.

     Since thorium and uranium are two of the most common radioactive elements on Earth, while also having three isotopes with half-lives on the order of several billion years, radon will be present on Earth long into the future despite its short half-life.  The decay of radon produces many other short-lived nuclides, known as radon daughters, ending at stable isotopes of lead.

     Unlike all other intermediate elements in the aforementioned decay chains, radon is, under standard conditions, gaseous and easily inhaled, and therefore a health hazard.  It is often the single largest contributor to an individual's background radiation dose, but due to local differences in geology, the level of exposure to radon gas differs from place to place.  A common source is uranium-containing minerals in the ground.  Due to its density, it can especially accumulate in subterranean areas such as basements.  Radon can also occur in some ground water like spring waters and hot springs.