radon

American  

[rey-don] / ˈreɪ dɒn /

noun

Chemistry.

1. a chemically inert, radioactive gaseous element produced by the decay of radium: emissions produced by outgassing of rock, brick, etc. are a health hazard. Rn; 86; 222.

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radon British  

/ ˈreɪdɒn /

noun

1. a colourless radioactive element of the rare gas group, the most stable isotope of which, radon-222, is a decay product of radium. It is used as an alpha particle source in radiotherapy. Symbol: Rn; atomic no: 86; half-life of ²²² Rn: 3.82 days; valency: 0; density: 9.73 kg/m³; melting pt: –71°C; boiling pt: –61.7°C

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radon Scientific  

/ rā′dŏn /

1. A colorless, odorless, radioactive element in the noble gas group. It is produced by the radioactive decay of radium and occurs in minute amounts in soil, rocks, and the air near the ground. Radon is used as a source of radiation for the treatment of cancer and other diseases. Its most stable isotope is Rn 222 with a half-life of 3.82 days. Atomic number 86; melting point −71°C; boiling point −61.8°C; specific gravity (solid) 4.

2. See Periodic Table

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radon Cultural  

1. A colorless, odorless, radioactive gas that is produced by the decay of radium in the soil.

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Discover More

Radon seeping through the ground and into buildings is a major source of indoor air pollution and may represent a significant risk for lung cancer.

Etymology

Origin of radon

First recorded in 1915–20; rad(ium) + -on ²

Example Sentences

Radon is a naturally occurring radioactive gas produced when metals like uranium or radium break down in rocks and soil.

From Science Daily • Jan. 31, 2024

“The uranium also releases a gas called radon gas, and in the mines, the radon levels are very very high. Radon is a carcinogen that could lead to lung cancer,” says Nemery.

From National Geographic • Dec. 21, 2023

Radon is a naturally occurring, odourless gas which comes from the rocks and soil found everywhere in the UK.

From BBC • Jul. 24, 2023

Radon is a colorless, odorless radioactive gas naturally generated from decaying elements in the ground.

From Seattle Times • Jun. 22, 2023

Radon apparently forms RnF2—evidence of this compound comes from radiochemical tracer techniques.

From Textbooks • Feb. 14, 2019