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Radon concentration can differ widely from place to place. In the open air, it ranges from 1 to 100 Bq/m 3, even less (0.1 Bq/m 3) above the ocean. In caves or ventilated mines, or poorly ventilated houses, its concentration climbs to 20–2,000 Bq/m 3. [79] Radon concentration can be much higher in mining contexts.
Radon-222 (222 Rn, Rn-222, historically radium emanation or radon) is the most stable isotope of radon, with a half-life of approximately 3.8 days. It is transient in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226 .
Mass number [222] Radon in the periodic table; Hydrogen: Helium: ... and the template adds the SI unit or additional standard text. While the topic is technical, we ...
), which is the most common naturally occurring isotope of uranium. It undergoes alpha decay to radon-222, which is also radioactive; the decay chain ultimately terminates at lead-206. Because of its occurrence in the 238 U decay chain, 226 Ra exists naturally at low concentrations in uranium-containing minerals, soil, and groundwater. [3]
The mass number (symbol A, from the German word: Atomgewicht, "atomic weight"), [1] also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units.
The atomic mass of atoms, ions, or atomic nuclei is slightly less than the sum of the masses of their constituent protons, neutrons, and electrons, due to (per E = mc 2). Atomic mass is often measured in dalton (Da) or unified atomic mass unit (u). One dalton is equal to 1 ⁄ 12 the mass of a carbon-12 atom in its natural state.
The radon levels in some of the mines can reach 400 to 700 kBq m −3. [17] A common unit of exposure of lung tissue to alpha emitters is the working level month (WLM), this is where the human lungs have been exposed for 170 hours (a typical month worth of work for a miner) to air which has 3.7 kBq of 222 Rn (in
There are 39 known isotopes of radon (86 Rn), from 193 Rn to 231 Rn; all are radioactive.The most stable isotope is 222 Rn with a half-life of 3.8235 days, which decays into 218 Po