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radon-222
Sign in to saveRadon-222 (222Rn, Rn-222, historically also radium emanation) is the most stable isotope of radon, with a half-life of 3.82146 days. It is an intermediate in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226. Radon-222 was first observed in 1899, and was identified as an isotope of a new element several years later. In 1957, the name radon, formerly the name of only radon-222, became the name of the element. Owing to its gaseous nature and high radioactivity, radon-222 is one of the leading causes of lung cancer.
Key facts
- Isotope.alternate_names
- Radium emanation
- Isotope.mass_number
- 222
- Isotope.symbol
- Rn
- Isotope.num_neutrons
- 136
- Isotope.num_protons
- 86
- Isotope.abundance
- Trace
- Isotope.decay_product
- Polonium-218
- Isotope.decay_mass
- 218
- Isotope.decay_symbol
- Po
- Isotope.parent
- Radium-226
- Isotope.parent_mass
- 226
- Isotope.parent_symbol
- Ra
- Isotope.parent_decay
- a
- Isotope.mass
- 222.0175760(21)
- Isotope.spin
- 0
- Isotope.decay_mode1
- Alpha decay
- Isotope.decay_energy1
- 5.590
via Wikipedia infobox
Article
6 sectionsContents
- History
- Decay properties
- Occurrence and hazards
- See also
- Notes
- References
Radon-222 (222Rn, Rn-222, historically also radium emanation) is the most stable isotope of radon, with a half-life of 3.82146 days. It is an intermediate in the decay chain of primordial uranium-238 and is the immediate decay product of radium-226. Radon-222 was first observed in 1899, and was identified as an isotope of a new element several years later. In 1957, the name radon, formerly the name of only radon-222, became the name of the element. Owing to its gaseous nature and high radioactivity, radon-222 is one of the leading causes of lung cancer.
==History== Following the 1898 discovery of radium through chemical analysis of radioactive ore, Marie and Pierre Curie observed a new radioactive substance emanating from radium in 1899 that was strongly radioactive for several days. Around the same time, Ernest Rutherford and Robert B. Owens observed a similar (though shorter-lived) emission from thorium compounds. German physicist Friedrich Ernst Dorn extensively studied these emanations in the early 1900s and attributed them to a new gaseous element, radon. In particular, he studied the product in the uranium series, radon-222, which he called radium emanation.