Radon (Rn)
noble-gasGas
Standard Atomic Weight
[222]Electron configuration
[Xe] 6s2 4f14 5d10 6p6Melting point
-71.15 °C (202 K)Boiling point
-61.7 °C (211.45 K)Density
9.73 kg/m³Oxidation states
0, +2, +6Electronegativity (Pauling)
N/AIonization energy (1st)
Discovery year
1900Atomic radius
N/ADetails
Radon is a radioactive noble gas and the heaviest naturally occurring member of group 18. It is chemically inert compared with most elements, but its radioactivity makes it environmentally and medically important. Natural radon is produced mainly in uranium and thorium decay chains, especially as ²²²Rn from radium-226. Its gaseous form lets it migrate from rocks, soils, and building materials into air and enclosed spaces.
Radon is present in the atomosphere at very low concentrations. See Wikipedia for discussion of concentration. At ordinary temperatures radon is a colorless 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. It has been reported that fluorine reacts with radon, forming a fluoride. Radon clathrates have also been reported.
Radon was discovered by Friedrich Ernst Dorn, a German chemist, in 1900 while studying radium's decay chain. Originally named niton after the Latin word for shining, nitens, radon has been known as radon since 1923. Today, radon is still primarily obtained through the decay of radium. At normal room temperatures, radon is a colorless, odorless, radioactive gas. The most common forms of radon decay through alpha decay. Alpha decay usually isn't considered to be a great radiological hazard since the alpha particles produced by the decay are easily stopped. However, since radon is a gas, it is easily inhaled and living tissue is directly exposed to the radiation. Although it has a relatively short half-life, radon decays into longer lived, solid, radioactive elements which can collect on dust particles and be inhaled as well. For these reasons, there is some concern as to the amount of radon present within homes. Radon seeps into houses as a result of the decay of radium, thorium or uranium ores underground and varies greatly from location to location. On average, the earth's atmosphere is 0.0000000000000000001% radon.
When cooled to its solid state, radon glows yellow. The glow becomes orange-red as the temperature is lowered.
Radon's most stable isotope, radon-222, has a half-life of about 3.8 days. It decays into polonium-218 through alpha decay.
The name was derived from radium; called niton at first, from the Latin word nitens meaning shining.The element was discovered in 1900 by Dorn, who called it radium emanation. In 1908 Ramsay and Gray, who named it niton, isolated the element and determined its density, finding it to be the heaviest known gas. It is essentially inert and occupies the last place in the zero group of gases in the Periodic Table. Since 1923, it has been called radon.
Images
Properties
Physical
Chemical
Thermodynamic
Nuclear
Abundance
Reactivity
N/A
Crystal Structure
N/A
Electronic Structure
Identifiers
Electron Configuration Measured
Rn: 4f¹⁴ 5d¹⁰ 6s² 6p⁶[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
No stable isotopes.
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 194 Radioactive | 194.006144 ± 0.000018 | N/A | 780 us |
| 217 Radioactive | 217.003928 ± 0.0000045 | N/A | 593 us |
| 199 Radioactive | 198.99839 ± 0.000068 | N/A | 590 ms |
| 214 Radioactive | 213.995363 ± 0.0000099 | N/A | 259 ns |
| 205 Radioactive | 204.991719 ± 0.000054 | N/A | 170 seconds |
Phase / State
Reason: 86.7 °C above boiling point (-61.7 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Density
At standard conditions
Estimated via ideal gas law at current T
Advanced
Atomic Spectra
Showing 10 of 86 Atomic Spectra. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Rn I | 0 | 67 | 0 | 10 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Rn I | 0 | 127 |
| Rn II | +1 | 3 |
| Rn III | +2 | 2 |
| Rn IV | +3 | 2 |
| Rn V | +4 | 2 |
| Rn VI | +5 | 2 |
| Rn VII | +6 | 2 |
| Rn VIII | +7 | 2 |
| Rn IX | +8 | 2 |
| Rn X | +9 | 2 |
Crystal structure data not available for solid phase
Crystal structure: fcc
Compounds
Isotopes (5)
Thirty-nine isotopes are known. Radon-222 is the most common. It has a half-life of 3.823 days and is an alpha emitter. It is estimated that every square mile of soil to a depth of 6 inches contains about 1 g of radium, which releases radon in tiny amounts into the atmosphere. Radon gas can collect in buildings, creating a health risk. The Environmental Protection Agency estimates that responsible for an estimated 20,000 lung cancer deaths each year. More on radon and health. Radon is present in some spring waters, such as those at Hot Springs, Arkansas.
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 194 Radioactive | 194.006144 ± 0.000018 | N/A | 780 us | α ≈100%β+ ? | |
| 217 Radioactive | 217.003928 ± 0.0000045 | N/A | 593 us | α =100% | |
| 199 Radioactive | 198.99839 ± 0.000068 | N/A | 590 ms | α ≈100%β+ ? | |
| 214 Radioactive | 213.995363 ± 0.0000099 | N/A | 259 ns | α =100% | |
| 205 Radioactive | 204.991719 ± 0.000054 | N/A | 170 seconds | β+ =75.4±0.9%α =24.6±0.9% |
Extended Properties
Covalent Radii (Extended)
Van der Waals Radii
Atomic & Metallic Radii
Numbering Scales
Electronegativity Scales
Polarizability & Dispersion
Noble Gas Properties
| HALOGENS | RnF2 |
Phase Transitions & Allotropes
| Melting point | 202.15 K |
| Boiling point | 211.45 K |
| Critical point (temperature) | 377.15 K |
| Critical point (pressure) | 6.28 MPa |
Oxidation State Categories
Advanced Reference Data
Screening Constants (15)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 1.6659 |
| 2 | p | 4.562 |
| 2 | s | 22.5864 |
| 3 | d | 13.4027 |
| 3 | p | 23.7194 |
| 3 | s | 24.9149 |
| 4 | d | 38.0572 |
| 4 | f | 37.6688 |
| 4 | p | 36.6988 |
| 4 | s | 35.85 |
Isotope Decay Modes (59)
| Isotope | Mode | Intensity |
|---|---|---|
| 193 | A | 100% |
| 194 | A | 100% |
| 194 | B+ | — |
| 195 | A | 100% |
| 196 | A | 100% |
| 196 | B+ | — |
| 197 | A | 100% |
| 197 | B+ | — |
| 198 | A | 93% |
| 198 | B+ | — |
X‑ray Scattering Factors (516)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 2.83964 |
| 10.1617 | — | 3.21791 |
| 10.3261 | — | 3.64656 |
| 10.4931 | — | 4.05083 |
| 10.6628 | — | 4.4288 |
| 10.8353 | — | 4.83437 |
| 11.0106 | — | 5.24445 |
| 11.1886 | — | 5.68932 |
| 11.3696 | — | 6.15277 |
| 11.5535 | — | 6.62072 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
4×10-13 milligrams per kilogram
References (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
6×10-16 milligrams per liter
References (1)
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Radon.
The element property data was retrieved from publications.