Radon

RADON BASIC FACTS
Atomic Number: 86

Symbol: Rn

Atomic Weight: 222.0176

Discovery: Fredrich Ernst Dorn 1898 or 1900 (Germany), discovered the element and called it radium emanation. Ramsay and Gray isolated the element in 1908 and named it niton.

Electron Configuration: [Xe] 4f14 5d10 6s2 6p6

Word Origin: from radium. Radon was once called niton, from the Latin word nitens, which means 'shining'

Isotopes: At least 34 isotopes of radon are known ranging from Rn-195 to Rn-228.


There are no stable isotopes of radon. The isotope radon-222 is the most stable isotope and called thoron and emanates naturally from thorium. Thoron is an alpha-emitter with a half-life of 3.8232 days. Radon-219 is called actinon and emanates from actinium. It is an alpha-emitter with a half-life of 3.96 sec.

Properties: Radon has a melting point of -71°C, boiling point of -61.8 °C, gas density of 9.73 g/l, specific gravity of the liquid state of 4.4 at -62°C, specific gravity of the solid state of 4, usually with a valence of 0 (it does form some compounds, however, such as radon fluoride). Radon is a colorless gas at normal temperatures. It is also the heaviest of the gases. When it is cooled below its freezing point it displays a brilliant phosphorescence. The phosphorescence is yellow as the temperature is lowered, becoming orange-red at the temperature of liquid air. Inhalation of radon presents a health risk.

Radon build-up is a health consideration when working with radium, thorium, or actinium. It is also a potential issue in uranium mines.

Sources: It is estimated that each square mile of soil to a depth of 6 inches contains approximately 1 g of radium, which releases radon to the atmosphere. The average concentration of radon is about 1 sextillion parts of air.


Radon naturally occurs in some spring waters.

Element Classification: Inert Gas