Radon Element Facts

The chemical element radon is classed as a noble gas and a nonmetal. It was discovered in 1900 by Fredrich E. Dorn.

Radioactivity intensity.

Average radioactivity intensity in the world's atmosphere caused by radon.


Data Zone

Classification: Radon is a noble gas and a nonmetal
Color: colorless
Atomic weight: (222), no stable isotopes
State: gas
Melting point: -71 oC, 202 K
Boiling point: -62 oC, 211 K
Electrons: 86
Protons: 86
Neutrons in most abundant isotope: 136
Electron shells: 2,8,18,32,18,8
Electron configuration: [Xe] 4f14 5d10 6s2 6p6
Density @ 20oC: 0.00973 g/cm3
Show more, including: Heats, Energies, Oxidation, Reactions, Compounds, Radii, Conductivities
Atomic volume: 50.5 cm3/mol
Specific heat capacity 0.09 J g-1 K-1
Heat of fusion 2.890 kJ mol-1
Heat of atomization 0 kJ mol-1
Heat of vaporization 16.40 kJ mol-1
1st ionization energy 1037 kJ mol-1
2nd ionization energy
3rd ionization energy
Electron affinity
Minimum oxidation number 0
Min. common oxidation no. 0
Maximum oxidation number 0
Max. common oxidation no. 0
Electronegativity (Pauling Scale)
Polarizability volume 5.3 Å3
Reaction with air none
Reaction with 15 M HNO3 none
Reaction with 6 M HCl none
Reaction with 6 M NaOH none
Oxide(s) none
Hydride(s) none
Chloride(s) none
Atomic radius
Ionic radius (1+ ion)
Ionic radius (2+ ion)
Ionic radius (3+ ion)
Ionic radius (1- ion)
Ionic radius (2- ion)
Ionic radius (3- ion)
Thermal conductivity 3.61 W m-1 K-1
Electrical conductivity
Freezing/Melting point: -71 oC, 202 K

Discovery of Radon

Radon gas was discovered in 1900 by Fredrich E. Dorn in Halle, Germany. He described it as radium emanation because it arose from the element radium, which he was working with.

In 1908 William Ramsay and Robert Gray isolated the gas and named it niton.

Since 1923, it has been called radon (after radium, one of its sources).

Radon was one of the earliest discovered radioactive elements, identified after uranium, thorium, polonium and radium.

Radon is the number one hazard in the home.

Appearance and Characteristics

Harmful effects:

Radon is highly radioactive and a carcinogen. Its decay products are toxic and radioactive. Radon is present in most homes and is the number one cause of lung-cancer in non-smokers in the USA. (See video on left.)


Radon is one of the noble gases; hence it is a chemically inert, monatomic gas.

It is also radioactive, colorless and odorless.

Radon is produced naturally by the decay of uranium’s decay products, such as 226Ra.

Uses of Radon

Radon was used for treating cancer by radiotherapy. Safer treatments are now available.

Abundance and Isotopes

Abundance earth’s crust: 4 x10-13 milligrams per kilogram

Abundance solar system:

Cost, pure: $ per 100g

Cost, bulk: $ per 100g

Source: Radon is produced naturally by the radioactive decay of uranium and other elements, such as radium. For example, 222Rn is produced by the decay of radium (226Ra).

Isotopes: Radon has 33 isotopes whose half-lives are known, with mass numbers 196 to 228. None are stable. The most stable isotope is 222Rn, with a half-life of 3.8 days.

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  1. Thanks so much for this, very useful for my project on Radon!