Radon: the essentials
At ordinary temperatures radon is a colourless gas. When cooled below the freezing point, radon exhibits a brilliant phosphorescence which becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air. The main hazard is from inhalation of the element and its decay products which are collected on dust in the air. Recently, radon buildup in homes from the surrounding soil and rocks has become a safety issue and some areas around the world test homes for radon gas. It is the heaviest known gas. Radon is present in some spring waters.
Radon is a decay product of the radium salts used in the luminous paint of the numerals. In this 1950's clock, the glass casing has accumulated 10-16 gram) of radon. Image adapted with permission from Prof James Marshall's (U. North Texas, USA) Walking Tour of the elements CD.
Radon: historical information
Radon was discovered in 1900 by Friedrich Ernst Dorn, who called it niton. It is essentially inert. It has been called radon since 1923, before which it was called niton.
Radon around us Read more »
Radon has no biological role.
Radon is the heaviest known gas and often found associated with uranium ores. Radon is present as a dissolved gas in some spring waters (such as those at Hot Springs, Arkansas, USA). Recently, radon buildup in homes from the surrounding soil and rocks has become a safety issue and some areas around the world test homes for radon gas.
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Physical properties Read more »
Heat properties Read more »
- Melting point: 202 [‑71 °C (‑96 °F)] K
- Boiling point: 211.3 [‑61.7 °C (‑79.1 °F)] K
- Enthalpy of fusion: |203| kJ mol-1
Crystal structure Read more »
The solid state structure of radon is: .
Radon: orbital properties Read more »
Radon atoms have 86 electrons and the shell structure is 18.104.22.168.18.8. The ground state electronic configuration of neutral Radon is [Xe].4f14.5d10.6s2.6p6 and the term symbol of Radon is 1S0.
- Pauling electronegativity: (no data) (Pauling units)
- First ionisation energy: 1037 kJ mol‑1
- Second ionisation energy: (no data) kJ mol‑1
Isolation: radon is present to a very small trace extent in the atmosphere and in principle could be obtained as a byproduct from the liquefaction and separation of air. However as only small quantities are ever needed in practice, and because of its short half life (the longest life isotope has a half life of less than 4 days), such quantities as are required are isolated through collection from the radioactive decay of an isotope of radium (226Ra, half life 1599 years).
226Ra → 222Rn + 4He
This method gives 0.64 cm3 of radon gas per gram of radium per month.
Radon isotopes Read more »