Radon (Rn)
noble-gasGas
Peso atómico estándar
[222]Configuración electrónica
[Xe] 6s2 4f14 5d10 6p6Punto de fusión
-71,15 °CPunto de ebullición
-61,7 °CDensidad
9,73 kg/m³Estados de oxidación
0, +2, +6Electronegatividad (Pauling)
N/DEnergía de ionización (1.ª)
10,7485 eVAño de descubrimiento
1900Radio atómico
N/DDetalles
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.
Pure radon is a colorless, odorless, monatomic gas at ordinary temperature and pressure. It can be condensed at low temperature to a liquid and then a solid, but macroscopic handling is limited by intense radioactivity and radiolytic effects.
Radon has no broad commercial use. Historically, sealed radon sources were used in some radiotherapy practices before safer and more controllable radionuclides became preferred. It has also been used as a tracer in hydrology, geology, and atmospheric studies because it is continuously generated in rocks and has isotope-dependent decay times. Present use is mainly analytical or research-related, including calibration and environmental measurement work.
Small amounts of radon are sometimes used by hospitals to treat some forms of cancer. Radon fluoride (RnF) is the only confirmed compound of radon.
Radon is still produced for therapeutic use by a few hospitals by pumping it from a radium source and sealing it in minute tubes, called seeds or needles, for application to patient. This practice has been largely discontinued as hospitals can get the seeds directly from suppliers, who make up the seeds with the desired activity for the day of use.
Isotopes in Earth/Planetary Science
Both 220Rn and 222Rn (with half-lives of 56 s and 3.8 days, respectively) are used to study underground environmental and atmospheric gaseous-transport processes [568] United States Geological Survey. Resources on Isotopes-Periodic Table-Radon, U.S. Geological Survey (2014), Feb. 25; http://wwwrcamnl.wr.usgs.gov/isoig/period/rn_iig.html., [569] State of California Department of Conservation. Indoor Radon, State of California Department of Conservation (2017), April 8; http://www.consrv.ca.gov/CGS/minerals/hazardous_minerals/radon/Pages/index.aspx., [570] L. S. Quindos Poncela, C. Sainz Fernandez, I. Fuente Merino, J. L. Gutierrez Villanueva, A. Gonzalez Diez. Acta Geophysica.61, 848 (2013).. The interaction of radon with streams and rivers enables it to be used as a tracer in groundwater studies (Fig. IUPAC.86.1). 222Rn has a short residence time in streams and river channels, which leads to radon loss. As a result, if an area of a stream or river has a high concentration of radon, it suggests that there are local groundwater inputs [568] United States Geological Survey. Resources on Isotopes-Periodic Table-Radon, U.S. Geological Survey (2014), Feb. 25; http://wwwrcamnl.wr.usgs.gov/isoig/period/rn_iig.html., [569] State of California Department of Conservation. Indoor Radon, State of California Department of Conservation (2017), April 8; http://www.consrv.ca.gov/CGS/minerals/hazardous_minerals/radon/Pages/index.aspx., [570] L. S. Quindos Poncela, C. Sainz Fernandez, I. Fuente Merino, J. L. Gutierrez Villanueva, A. Gonzalez Diez. Acta Geophysica.61, 848 (2013).. In a deep (100 m) contaminated aquifer at a refinery site in Mexico, where the contaminated source was too deep to be directly accessible for sampling, Schubert et al. [571] M. Schubert, M. Balcazar, A. Lopez, P. Peña, J. H. Flores, K. Knöller. Isot. Environ. Health Stud.43, 215 (2007). collected groundwater samples from a few wells available at the site. They used the partitioning of the natural tracer 222Rn between uncontaminated groundwater and the NAPL (non-aqueous phase-liquid, such as oil, gasoline, and petroleum) source zone, and they were able to approximately identify the location of the NAPL source zone. As noted in Section 4.88.1, 222Rn has been used to quantify submarine groundwater discharge [572] R. N. Peterson, W. C. Burnett, M. Taniguchi, J. Chen, I. R. Santos, T. Ishitobi. J. Geophys. Res.113, C09021 (2008)..
Isotopes in Geochronology
222Rn has been used as a tool to date groundwater in combination with other isotopes or elemental ratios (i.e. helium/radon and xenon/radon amount ratios) [568] United States Geological Survey. Resources on Isotopes-Periodic Table-Radon, U.S. Geological Survey (2014), Feb. 25; http://wwwrcamnl.wr.usgs.gov/isoig/period/rn_iig.html., [574] T. F. Kraemer, D. P. Genereux. “Applications of uranium- and thorium-series radionuclides in catchment hydrology studies”, in Isotope Tracers in Catchment Hydrology, C. Kendall, J. J. McDonnell (Eds.), Elsevier, Amsterdam (1998)..
Radon is the least chemically studied noble gas because its isotopes are radioactive and available only in small amounts. The most established chemistry involves strong oxidizing and fluorinating conditions, with radon difluoride (RnF₂) reported as a radon compound. Ionic or complex fluoride species have been inferred in matrix and tracer experiments, but many details remain uncertain. Oxidation states above 0 are possible in principle, yet radon chemistry is much less developed than xenon chemistry.
See more information at the Radon compound page.
Radon is hazardous chiefly because inhaled radioactive decay products can lodge in the respiratory tract and irradiate tissue with alpha particles. The risk depends strongly on isotope, concentration, ventilation, exposure time, and the behavior of short-lived progeny such as polonium isotopes. Radon is also an asphyxiant like other gases if present at very high concentrations, but radiation exposure is the practical concern.
Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/l.
Radon forms naturally where uranium or thorium decay occurs in minerals and soils. Being a gas, it can diffuse through pore spaces, dissolve to some extent in groundwater, and enter buildings through cracks or service penetrations. Outdoors it is usually diluted rapidly, while enclosed or poorly ventilated spaces can accumulate higher concentrations. Its decay products attach to aerosols and surfaces, changing their mobility and exposure pathways.
Radon is not traded as a normal industrial commodity. It is generated continuously by decay of radium in sealed sources or collected in small quantities for specialized calibration and research needs. Supply is constrained less by elemental scarcity than by radiological controls, isotope half-lives, and the limited demand for handling the gas. Most practical applications that once used radon have been replaced by other radionuclides, electronic instruments, or direct environmental monitoring methods.
Formed from the decay of radium in the earths crust.
Radon has no stable isotopes, so it cannot accumulate over geological or cosmic timescales. In nature it appears only as a transient daughter in decay chains of long-lived heavy nuclides such as uranium and thorium. In extraterrestrial materials, any radon would likewise be short-lived and locally produced rather than primordial.
- Radon is the densest noble gas encountered naturally on Earth.
- The isotope ²²²Rn has a half-life of about 3.8 days, long enough for migration through soil.
- Radon was once called niton, a name reflected in the old symbol Nt.
- Indoor radon levels often vary with season, pressure differences, and building ventilation.
- Radon measurements can reveal subsurface gas movement and some groundwater interactions.
Imágenes
Propiedades
Físicas
- Radio covalente
- 150 pm Comparar Radio covalente de todos los elementos →
- Radio de van der Waals
- 220 pm Comparar Radio de van der Waals de todos los elementos →
- Densidad
- 9,73 kg/m³ Comparar Densidad de todos los elementos →
- Fase en CNPT
- Gas Comparar Fase en CNPT de todos los elementos →
- Punto de fusión
- -71,15 °C Comparar Punto de fusión de todos los elementos →
- Punto de ebullición
- -61,7 °C Comparar Punto de ebullición de todos los elementos →
- Conductividad térmica
- 0,004 W/(m·K) Comparar Conductividad térmica de todos los elementos →
- Capacidad calorífica específica
- 0,094 J/(g·K) Comparar Capacidad calorífica específica de todos los elementos →
- Capacidad calorífica molar
- 20,786 J/(mol·K) Comparar Capacidad calorífica molar de todos los elementos →
- Estructura cristalina
- Cúbica centrada en las caras Comparar Estructura cristalina de todos los elementos →
Químicas
- Electronegatividad (Allen)
- 2,6
- Afinidad electrónica
- -0,7 eV (valor negativo: se predice que el átomo no capta un electrón adicional)
- Energía de ionización (1.ª)
- 10,7485 eV Comparar Energía de ionización (1.ª) de todos los elementos →
- Energía de ionización (2.ª)
- 18,990065 eV Comparar Energía de ionización (2.ª) de todos los elementos →
- Energía de ionización (3.ª)
- 29,400101 eV Comparar Energía de ionización (3.ª) de todos los elementos →
- Energía de ionización (4.ª)
- 36,900127 eV Comparar Energía de ionización (4.ª) de todos los elementos →
- Energía de ionización (5.ª)
- 52,900182 eV Comparar Energía de ionización (5.ª) de todos los elementos →
- Estados de oxidación
- 0, +2, +6 Comparar Estados de oxidación de todos los elementos →
- Electrones de valencia
- 8 Comparar Electrones de valencia de todos los elementos →
- Configuración electrónica
- [Xe] 6s2 4f14 5d10 6p6
Termodinámicas
- Punto triple (temperatura)
- -71 °C
- Punto triple (presión)
- 5,1e+4 Pa
- Punto crítico (temperatura)
- 104 °C
- Punto crítico (presión)
- 6,28e+6 Pa
- Calor de fusión
- 0,03109292 eV Comparar Calor de fusión de todos los elementos →
- Calor de vaporización
- 0,16582889 eV Comparar Calor de vaporización de todos los elementos →
- Calor de atomización
- 0 eV
Nucleares
- Protones
- 86 Comparar Protones de todos los elementos →
- Neutrones
- 136 Comparar Neutrones de todos los elementos →
- Isótopos conocidos
- 39 Comparar Isótopos conocidos de todos los elementos →
- Isótopos estables
- 0 Comparar Isótopos estables de todos los elementos →
- Número másico (isótopo más estable)
- 222
- Isótopo más estable
- Rn-222
- Año de descubrimiento
- 1900
Abundancia
- Abundancia (corteza terrestre)
- 4e-13 mg/kg Comparar Abundancia (corteza terrestre) de todos los elementos →
- Abundancia (océano)
- 6 × 10−16 mg/L Comparar Abundancia (océano) de todos los elementos →
Estructura cristalina
N/D
Estructura electrónica
- Electrones por capa
- 2, 8, 18, 32, 18, 8 Comparar Electrones por capa de todos los elementos →
Identificadores
- Número CAS
- 10043-92-2 Comparar Número CAS de todos los elementos →
- Símbolo del término
- 1S0
- InChI
- InChI=1S/Rn
- Clave InChI
- SYUHGPGVQRZVTB-UHFFFAOYSA-N
Configuración electrónica Medido
Rn: 4f¹⁴ 5d¹⁰ 6s² 6p⁶[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶Modelo atómico
Los isótopos cambian el número de neutrones, la masa y la estabilidad, pero no la configuración electrónica de un átomo neutro.
Modelo atómico esquemático, no a escala.
Huella atómica
Espectro de emisión / absorción
Distribución isotópica
No hay isótopos estables.
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración |
|---|---|---|---|
| 194 Radiactivo | 194,006144 ± 0,000018 | N/D | 780 us |
| 217 Radiactivo | 217,003928 ± 0,0000045 | N/D | 593 us |
| 199 Radiactivo | 198,99839 ± 0,000068 | N/D | 590 ms |
| 214 Radiactivo | 213,995363 ± 0,0000099 | N/D | 259 ns |
| 205 Radiactivo | 204,991719 ± 0,000054 | N/D | 170 segundos |
Fase / Estado
Motivo: 86,7 °C por encima del punto de ebullición (-61,7 °C)
Esquemático, no a escala
Puntos de transición de fase
Energías de transición
Energía necesaria para fundir 1 mol en el punto de fusión
Energía necesaria para vaporizar 1 mol en el punto de ebullición
Densidad
En condiciones estándar
Estimada mediante la ley de los gases ideales a la T actual
Avanzado
Espectros atómicos
Se muestran 10 de 86. Ordenado por carga del ion (ascendente).
Líneas disponibles ?
| Ion | Carga | Total de líneas | Probabilidades de transición | Designaciones de los niveles |
|---|---|---|---|---|
| Rn I | 0 | 67 | 0 | 10 |
Niveles disponibles ?
| Ion | Carga | Niveles |
|---|---|---|
| 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 |
No hay datos disponibles sobre la estructura cristalina de la fase sólida
Estructura cristalina: fcc
Compuestos
Isótopos (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.
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración | Modo de desintegración | |
|---|---|---|---|---|---|
| 194 Radiactivo | 194,006144 ± 0,000018 | N/D | 780 us | α ≈100%β+ ? | |
| 217 Radiactivo | 217,003928 ± 0,0000045 | N/D | 593 us | α =100% | |
| 199 Radiactivo | 198,99839 ± 0,000068 | N/D | 590 ms | α ≈100%β+ ? | |
| 214 Radiactivo | 213,995363 ± 0,0000099 | N/D | 259 ns | α =100% | |
| 205 Radiactivo | 204,991719 ± 0,000054 | N/D | 170 segundos | β+ =75.4±0.9%α =24.6±0.9% |
Propiedades ampliadas
Radios covalentes (ampliados)
- Radio covalente (Pyykkö)
- 142 pm
- Radio covalente (Pyykkö, enlace doble)
- 145 pm
- Radio covalente (Pyykkö, enlace triple)
- 133 pm
Radios de van der Waals
- Truhlar
- 220 pm
- Alvarez
- 240 pm
- UFF
- 476,5 pm
- MM3
- 243 pm
Radios atómicos y metálicos
- Radio atómico (Rahm)
- 243 pm
Escalas de numeración
- Mendeleev
- 117
- Pettifor
- 6
- Glawe
- 6
Escalas de electronegatividad
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 4
Polarizabilidad y dispersión
- Polarizabilidad dipolar
- 35 a.u.
- Polarizabilidad dipolar (incert.)
- 2 a.u.
- C₆ (Gould–Bučko)
- 408 Ha·Bohr6
Propiedades de los gases nobles
| HALOGENS | RnF2 |
Transiciones de fase y alótropos
| Punto de fusión | 202,15 K |
| Punto de ebullición | 211,45 K |
| Punto crítico (temperatura) | 377,15 K |
| Punto crítico (presión) | 6,28 MPa |
Categorías de estados de oxidación
Datos de referencia avanzados
Constantes de apantallamiento (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 |
Modos de desintegración de los isótopos (59)
| Isótopo | Modo | Intensidad |
|---|---|---|
| 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+ | — |
Factores de dispersión de rayos X (516)
| Energía (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 |
Datos adicionales
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
4×10-13 milligrams per kilogram
Referencias (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
6×10-16 milligrams per liter
Referencias (1)
Referencias
(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.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
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.