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About Radon

Radon Bohr

Radon is a radioactive noble gas that occurs naturally on earth as a decay product of uranium and thorium deposits. The initial discovery of this element has variously been credited to Pierre and Marie Curie, who in 1899 noted that gas emitted by the previously discovered element radium remained active for some time, Friedrich Ernst Dorn, who noted the same phenomenon in 1900, Ernest Rutherford, who observed radioactive gas being emitted by thorium samples in 1901, and Andre-Louis Debierne, who observed radioactive gas emitted by actinium in 1903. Initially the gases emitted by each separate element were given different names, but it was eventually recognized that all three were merely different isotopes of a single new element of the noble gas family.

This new element was extensively characterised by Sir William Ramsay and Robert Whytlaw-Gray in 1910, and was later given the single element name “radon” accompanied by isotope numbers in place of the separate names for each isotope. Through the 1960’s the historical tradition of referring to the radioactive gas as an “emanation” from a given radioactive element remained in use to some degree.

Due to its radioactivity and presence in natural deposits, radon constitutes a major health hazard, contributing to lung cancer in those exposed. Typically, exposure occurs as a result of leaks from underground, and both radon gas and small particles of its solid decay products may be inhaled, leading to radiation exposure in lung tissue. Radon’s primary application is in cancer treatment, as it can be sealed into tiny metal seeds that are implanted into tumors for continuous radiotherapy. Additionally, it is sometimes used as a radioactive tracer to check structures for gas leaks.

Radon Properties

Radon Bohr ModelRadon is a Block P, Group 18, Period 6 element. The number of electrons in each of Radon's shells is 2, 8, 18, 32, 18, 8 and its electronic configuration is [Xe] 4f14 5d106s26p6. In its elemental form radon's CAS number is 10043-92-2. The radon atom has a covalent radius of and it's Van der Waals radius is Radon is produced by the radioactive decay of radium-226, which is found in phosphate, igneous and metamorphic rocks as well as uranium ores and shales. It was first isolated by William Ramsay and Robert Whytlaw-Gray in 1910. The name radon is derived from the element radium. At first radon was called niton, from the Latin word ‘Nitens’ which means shining.

Radon is highly radioactive and a carcinogen. Radon information, including technical data, properties, and other useful facts are specified below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity, and thermal properties are included.

Symbol: Rn
Atomic Number: 86
Atomic Weight: 222
Element Category: noble gases
Group, Period, Block: 18, 6, p
Color: colorless
Other Names: Rádon
Melting Point: -71°C, -95.8°F, 202.15 K
Boiling Point: -61.7°C, -79.06°F, 211.45 K
Density: 440 (liquid 211 K) kg·m3
Liquid Density @ Melting Point: 4.4 g·cm3
Density @ 20°C: 0.00973 g/cm3
Density of Solid: 4400 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: 377 K, 6.28 MPa
Heat of Fusion (kJ·mol-1): 2.7
Heat of Vaporization (kJ·mol-1): 18.1
Heat of Atomization (kJ·mol-1): 0
Thermal Conductivity: 3.61 m W·m-1·K-1
Thermal Expansion: N/A
Electrical Resistivity: N/A
Tensile Strength: N/A
Molar Heat Capacity: 5R/2 = 20.786 J·mol-1·K-1
Young's Modulus: N/A
Shear Modulus: N/A
Bulk Modulus: N/A
Poisson Ratio: N/A
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: N/A
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: N/A
Mulliken-Jaffe Electronegativity: 2.59 (12.5% s orbital)
Allen Electronegativity: N/A
Pauling Electropositivity: N/A
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 86
Protons: 86
Neutrons: 136
Electron Configuration: [Xe] 4f14 5d106s26p6
Atomic Radius: N/A
Atomic Radius,
non-bonded (Å):
Covalent Radius: 150 pm
Covalent Radius (Å): 1.46
Van der Waals Radius: 220 pm
Oxidation States: 6, 2, 0
Phase: Gas
Crystal Structure: face-centered cubic
Magnetic Ordering: non-magnetic
Electron Affinity (kJ·mol-1) Not stable
1st Ionization Energy: 1037.08 kJ·mol-1
2nd Ionization Energy: N/A
3rd Ionization Energy: N/A
CAS Number: 10043-92-2
EC Number: N/A
MDL Number: N/A
Beilstein Number: N/A
SMILES Identifier: [Rn]
InChI Identifier: InChI=1S/Rn
PubChem CID: 24857
ChemSpider ID: 23240
Earth - Total: N/A
Mercury - Total: N/A
Venus - Total: N/A
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: N/A
Earth -  Crust (Crustal Rocks), ppb by atoms: N/A
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Friedrich Ernst Dorn
Discovery Date: 1898
First Isolation: William Ramsay and Robert Whytlaw-Gray (1910)

Radon Isotopes

Radon has 39 known isotopes. Four of them, 218Rn, 219Rn, 220Rn and 222Rn, occur in trace quantities in nature.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
193Rn 193 Unknown Unknown N/A N/A N/A -
194Rn 194 Unknown Unknown N/A N/A N/A -
195Rn 195.00544(5) 6 ms Unknown 3/2-# N/A N/A -
196Rn 196.002115(16) 4.7(11) ms [4.4(+13-9) ms] α to 192Po 0+ N/A N/A -
197Rn 197.00158(7) 66(16) ms [65(+25-14) ms] α to 193Po 3/2-# N/A 1521.220947 -
198Rn 197.998679(14) 65(3) ms α to 194Po; β+ to 198Ar 0+ N/A 1531.975952 -
199Rn 198.99837(7) 620(30) ms α to 195Po; β+ to 199Ar 3/2-# N/A 1540.485962 -
200Rn 199.995699(14) 0.96(3) s α to 196Po; β+ to 200Ar 0+ N/A 1551.009033 -
201Rn 200.99563(8) 7.0(4) s α to 197Po; β+ to 201Ar (3/2-) N/A 1559.212036 -
202Rn 201.993263(19) 9.94(18) s α to 198Po; β+ to 202Ar 0+ N/A 1569.442993 -
203Rn 202.993387(25) 44.2(16) s α to 199Po; β+ to 203Ar (3/2-) N/A 1577.421997 -
204Rn 203.991429(16) 1.17(18) min α to 200Po; β+ to 204Ar 0+ N/A 1587.311035 -
205Rn 204.99172(5) 170(4) s β+ to 205Ar; α to 201Po 5/2- N/A 1595.099976 -
206Rn 205.990214(16) 5.67(17) min α to 202Po; β+ to 206Ar 0+ N/A 1604.57605 -
207Rn 206.990734(28) 9.25(17) min β+ to 207Ar; α to 203Po 5/2- N/A 1612.119385 -
208Rn 207.989642(12) 24.35(14) min α to 204Po; β+ to 208Ar 0+ N/A 1628.588135 -
209Rn 208.990415(21) 28.5(10) min β+ to 209Ar; α to 205Po 5/2- N/A 1621.211182 -
210Rn 209.989696(9) 2.4(1) h EC to 210At 0+ N/A 1637.308594 -
211Rn 210.990601(7) 14.6(2) h EC to 211At; α to 207Po 1/2- 0.6 1644.536377 -
212Rn 211.990704(3) 23.9(12) min α to 208Po 0+ N/A 1652.51123 -
213Rn 212.993883(6) 19.5(1) ms α to 209Po (9/2+) N/A 1657.620972 -
214Rn 213.995363(10) 0.27(2) µs α to 210Po 0+ -0.02 1664.315552 -
215Rn 214.998745(8) 2.30(10) µs α to 211Po 9/2+ N/A 1669.235718 -
216Rn 216.000274(8) 45(5) µs α to 212Po 0+ N/A 1675.882812 -
217Rn 217.003928(5) 0.54(5) ms α to 213Po 9/2+ N/A 1680.548218 -
218Rn 218.0056013(25) 35(5) ms α to 214Po 0+ N/A 1687.062378 -
219Rn 219.0094802(27) 3.96(1) s α to 215Po 5/2+ N/A 1691.511597 -
220Rn 220.0113940(24) 55.6(1) s α to 216Po 0+ N/A 1697.804321 -
221Rn 221.015537(6) 25.7(5) min α to 217Po; β- to 221Fr 7/2(+) N/A 1702.083984 -
222Rn 222.0175777(25) 3.8235(3) d α to 218Po 0+ N/A 1708.184448 -
223Rn 223.02179(32)# 24.3(4) min α to 219Po; β- to 223Fr 7/2 N/A 1712.324951 -
224Rn 224.02409(32)# 107(3) min β- to 224Fr 0+ N/A 1718.254028 -
225Rn 225.02844(32)# 4.66(4) min β- to 225Fr 7/2- N/A 1722.274048 -
226Rn 226.03089(43)# 7.4(1) min β- to 226Fr 0+ N/A 1728.062988 -
227Rn 227.03541(45)# 20.8(7) s β- to 227Fr 5/2(+#) N/A 1731.927002 -
228Rn 228.03799(44)# 65(2) s β- to 228Fr 0+ N/A 1737.504028 -
229Rn 229.0426536(141) 12 s Unknown N/A N/A N/A -
230Rn 230 Unknown Unknown N/A N/A N/A -
231Rn 231 Unknown Unknown N/A N/A N/A -
Radon Elemental Symbol

Recent Research & Development for Radon

  • Lung cancer risk from radon exposure in dwellings in Sweden: how many cases can be prevented if radon levels are lowered? Axelsson G, Andersson EM, Barregard L. Cancer Causes Control. 2015 Feb 13.
  • Radon mitigation in cold climates at Kitigan Zibi Anishinabeg. Brossard M, Ottawa CB, Falcomer R, Whyte J. Health Phys. 2015 Feb
  • Coagulation effect on the activity size distributions of long lived radon progeny aerosols and its application to atmospheric residence time estimation techniques. Anand S, Mayya YS. J Environ Radioact. 2015 Jan 19
  • Estimation of radon prone areas through binary classification, part 2: radon prone geologies. Bossew P. J Environ Radioact. 2014 Dec 17
  • A comparative study between the dynamic method and passive can technique of radon exhalation measurements from samples. Raj Menon S, Sahoo BK, Balasundar S, Gaware JJ, Jose MT, Venkatraman B, Mayya YS. Appl Radiat Isot. 2015 Feb 7
  • Log-normality of indoor radon data in the Walloon region of Belgium. Cinelli G, Tondeur F. J Environ Radioact. 2015 Mar 6
  • Method for determining individual deposition velocities of radon progeny. Angell CT, Pedretti M, Norman EB. Appl Radiat Isot. 2015 Apr
  • [When radon is beneficial to health.] Maraver F, Martín-Megías AI, Corvillo I, Armijo F. Gac Sanit. 2014 Dec 29.
  • On the calibration of a radon exhalation monitor based on the electrostatic collection method and accumulation chamber. Tan Y, Tokonami S, Hosoda M. J Environ Radioact. 2015 Mar 12
  • [Can a recognized human carcinogen such as radon be healthy?] Ruano-Ravina A, Quindós-Poncela L, Fernández CS, Barros-Dios JM. Gac Sanit. 2015 Jan 20.
  • Surface-deposition and distribution of the radon-decay products indoors. Espinosa G, Tommasino L. J Environ Radioact. 2015 Mar 4
  • Temporal variability of radon in a remediated tailing of uranium ore processing - the case of Urgeiriça (central Portugal). Barbosa SM, Lopes F, Correia AD, Barbosa S, Pereira AC, Neves LF. J Environ Radioact. 2015 Jan 22
  • Winnipeg radon testing: comparison of test durations, effects of house characteristics, and efficacy of floor-drain seals. Warkentin PE, Johnson HM. Health Phys. 2015 Apr
  • Radon sources and associated risk in terms of exposure and dose. Vogiannis EG, Nikolopoulos D. Front Public Health. 2015 Jan 5
  • Associations of DNA-repair gene polymorphisms with a genetic susceptibility to ionizing radiation in residents of areas with high radon (222Rn) concentration. Sinitsky MY, Larionov AV, Asanov MA, Druzhinin VG. Int J Radiat Biol. 2015 Feb 27:1-9.
  • Optical realization of the radon transform. Ilovitsh T, Ilovitsh A, Sheridan J, Zalevsky Z. Opt Express. 2014 Dec 29
  • Stochastic rat lung dosimetry for inhaled radon progeny: a surrogate for the human lung for lung cancer risk assessment. Winkler-Heil R, Hussain M, Hofmann W. Radiat Environ Biophys. 2015 Feb 28.
  • Energy-efficient reconstructions and indoor radon: the impact assessed by CDs/DVDs. Pressyanov D, Dimitrov D, Dimitrova I. J Environ Radioact. 2015 Mar 4
  • Evaluation of radon adsorption characteristics of a coconut shell-based activated charcoal system for radon and thoron removal applications. Karunakara N, Sudeep Kumara K, Yashodhara I, Sahoo BK, Gaware JJ, Sapra BK, Mayya YS. J Environ Radioact. 2015 Feb 3