What is Radon? Electron configuration, Atomic Number & Mass

Radon is a chemical element numbered 86  in the Periodic Table of the Elements.

General informations



Atomic number



Noble gas







Volumic mass

9.73 gL -1



Atomic properties

Atomic mass

222 u

Atomic radius

120 pm

Electronic configuration

[Xe] 6s 2 4f 14 5d 10 6p 6

Electrons by energy level

2 | 8 | 18 | 32 | 18 | 8



Physical properties

Ordinary state


Fusion point

-71 ° C

Boiling point

-61.7 ° C

A little history


The name of the chemical element 86, radon, was formed in such a way as to evoke its source - indeed, it is one of the products of the decay of radium - but also to recall its chemical family since it is part noble gasses all having an en - on termination .

The origin of the name is the variation of the name of the element radium: originally radon was called niton, from the Latin word nitens meaning to shine.

When it was discovered, it was designated by "radon emanation" then other names were proposed to designate this element as well as its isotopes which were initially considered as distinct elements.

It was not until 1923 that the international committee of the elements as well as the IUPAC validated the names of radon, thoron and action for the isotopes of the element 86 but only the first of this list will remain.

Know about Neon


It all began in 1899, when Pierre and Marie Curie, studying the radioactivity of radium, realized that the gas emitted by radium remained radioactive for nearly a month.

During this same year, the chemists Robert Bowie Owens and Ernest Rutherford, noting variable results when measuring the radioactivity of thorium oxides.

Rutherford then noted that the thorium compounds were capable of continuously emitting a radioactive gas which retained its radioactivity for several minutes. He will then decide to name this gas, first of all, emanation then emanation of thorium, symbol ThEm

Radon was finally discovered in 1900 by the scientist Friedrich Ernst Dorn, calling this third radioactive element, after radium and polonium, emanation of radium, with the symbol RaEm. Dorn arrived at this discovery thanks to his experiments which will show that radium is able to emit a radioactive gas.

A year later, it will be Rutherford who will demonstrate that thorium emanations are radioactive. However, he will credit Pierre and Marie Curie for the discovery of this element.

Two years later, in 1903, André-Louis Debierne observed a phenomenon identical to radium and thorium but originating from actinium. He will name this gas, actinium emanation, symbol AcEm.

However and after study, Sir William Ramsay suggested in 1904 in view of the similarity of the spectrum of the three gases discovered with argon, krypton and xenon and, in view of their chemical inertia, that the different emanations discovered could actually correspond to a new chemical element classified in the family of rare gases.

It will be finally in 1908 that William Ramsay and Robert Whytlaw-Gray will isolate a gas which they will call niton, coming from the Latin nitens meaning brilliant. They also determined the density of this gas.

A few years later, in 1910, the two collaborators isolated radon by determining that it was the most dense gas among those known at the time and decided to call it niton as a reminder of the property of this gas capable of rendering phosphorescent substances.

Know about Promethium

Presence in its natural state

Radon is formed naturally by the decay of radium within the radioactive decay chain of uranium but also of thorium which is naturally contained in rocks or soil, more particularly in volcanic, granitic and uranium-bearing areas.

However, the radon level observable in nature is so low that it is not detected by chemical analyzes but by measuring its radioactivity.

Physical and chemical properties

Radon as a single body

Radon is a colorless, odorless, heavy and noble radioactive gas that is chemically inert and non-flammable but is highly radio toxic and carcinogenic by inhalation. Radon is formed from the decay of radium in the earth's crust.

It is, more precisely, a very dense monoatomic gas, soluble in water and which, like the other members of the noble gas family, is chemically inert. It therefore does not react with the other compounds.

Indeed, noble gasses exhibit properties which agree perfectly with the structure of atoms described in modern literature: their valence layer is saturated. As a result, they cannot establish a covalent bond with other atoms, which explains their chemical inertia.

When it is cooled enough to pass to the solid state, it takes an orange-red color, becomes phosphorescent and shines under the effect of the radiation emitted during radioactive decay.

Radon ions in aqueous solution

Due to its stable electronic structure, radon cannot pick up or lose electrons. Therefore, it cannot form ions.

Radon-based compounds

Like all rare gasses, radon has an electronic structure which gives it a particular stability and which does not allow the formation of covalent or ionic bonds. There are therefore no stable compounds of radon.


Radon is a chemical element with 35 isotopes with a mass number between 195 and 229.

It should be noted, however, that, among these 35 isotopes, only 4 exist in nature since the others are only in trace amounts. In addition, only radon-222 has a sufficiently long half-life to present a radiation protection problem in extreme cases.

Know about Ytterbium


Radon is mainly used in the treatment of cancerous tumors, but it is also used as radioactive tracers of so-called continental air masses. Indeed, it would seem that certain radon anomalies are observed during earthquakes or volcanic eruptions.


Radon, because of its radioactivity, can present certain risks.

Indeed, breathing too high concentrations of radon can cause various lung diseases while long-term exposure would promote the appearance of cancer.


Radon is a radioactive gas that is relatively rarely present naturally in the environment. However, humans can increase their concentrations by burning coal or by mining uranium or phosphate.

However, given the element's very short half-life, most radon degrades into generally less dangerous elements, minimizing its ecotoxic side.

Know about more periodic elements- Aluminium, Gadolinium, Germanium, Neon, Oxygen, Potassium, Promethium, Selenium, Sodium, Terbium, Tellurium, Yttrium, Ytterbium, Zirconium

Related Articales


Download Our App (1Mb Only)
To get FREE PDF & Materials