Radon (Rn)
noble-gasGas
标准原子量
[222]电子排布
[Xe] 6s2 4f14 5d10 6p6熔点
-71.15 °C沸点
-61.7 °C密度
9.73 kg/m³氧化态
0, +2, +6电负性（鲍林）
暂无第一电离能
10.7485 eV发现年份
1900原子半径
暂无详细信息
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.
图片
性质
物理性质
- 共价半径
- 150 pm 比较所有元素的共价半径 →
- 范德华半径
- 220 pm 比较所有元素的范德华半径 →
- 密度
- 9.73 kg/m³ 比较所有元素的密度 →
- 标准温度和压力下的物相
- 气态 比较所有元素的标准温度和压力下的物相 →
- 熔点
- -71.15 °C 比较所有元素的熔点 →
- 沸点
- -61.7 °C 比较所有元素的沸点 →
- 热导率
- 0.004 W/(m·K) 比较所有元素的热导率 →
- 比热容
- 0.094 J/(g·K) 比较所有元素的比热容 →
- 摩尔热容
- 20.786 J/(mol·K) 比较所有元素的摩尔热容 →
- 晶体结构
- 面心立方 比较所有元素的晶体结构 →
化学性质
- 电负性（Allen）
- 2.6
- 电子亲和能
- -0.7 eV (负值——预计该原子不结合额外电子)
- 第一电离能
- 10.7485 eV 比较所有元素的第一电离能 →
- 第二电离能
- 18.990065 eV 比较所有元素的第二电离能 →
- 第三电离能
- 29.400101 eV 比较所有元素的第三电离能 →
- 第四电离能
- 36.900127 eV 比较所有元素的第四电离能 →
- 第五电离能
- 52.900182 eV 比较所有元素的第五电离能 →
- 氧化态
- 0, +2, +6 比较所有元素的氧化态 →
- 价电子
- 8 比较所有元素的价电子 →
- 电子排布
- [Xe] 6s2 4f14 5d10 6p6
热力学性质
- 三相点（温度）
- -71 °C
- 三相点（压力）
- 5.1e+4 Pa
- 临界点（温度）
- 104 °C
- 临界点（压力）
- 6.28e+6 Pa
- 熔化热
- 0.03109292 eV 比较所有元素的熔化热 →
- 汽化热
- 0.16582889 eV 比较所有元素的汽化热 →
- 原子化热
- 0 eV
核性质
- 质子
- 86 比较所有元素的质子 →
- 中子
- 136 比较所有元素的中子 →
- 已知同位素
- 39 比较所有元素的已知同位素 →
- 稳定同位素
- 0 比较所有元素的稳定同位素 →
- 质量数（最稳定同位素）
- 222
- 最稳定同位素
- Rn-222
- 发现年份
- 1900
丰度
- 丰度（地壳）
- 4e-13 mg/kg 比较所有元素的丰度（地壳） →
- 丰度（海洋）
- 6 × 10−16 mg/L 比较所有元素的丰度（海洋） →
晶体结构
暂无
电子结构
- 各电子层电子数
- 2, 8, 18, 32, 18, 8 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 10043-92-2 比较所有元素的CAS登记号 →
- 谱项符号
- 1S0
- InChI
- InChI=1S/Rn
- InChI Key
- SYUHGPGVQRZVTB-UHFFFAOYSA-N
电子排布 实测值
Rn: 4f¹⁴ 5d¹⁰ 6s² 6p⁶[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁶原子模型
不同同位素的中子数、质量和稳定性不同，但中性原子的电子排布不变。
原子模型示意图，未按比例绘制。
原子指纹
发射 / 吸收光谱
同位素分布
无稳定同位素。
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 |
|---|---|---|---|
| 194 放射性 | 194.006144 ± 0.000018 | 暂无 | 780 us |
| 217 放射性 | 217.003928 ± 0.0000045 | 暂无 | 593 us |
| 199 放射性 | 198.99839 ± 0.000068 | 暂无 | 590 ms |
| 214 放射性 | 213.995363 ± 0.0000099 | 暂无 | 259 ns |
| 205 放射性 | 204.991719 ± 0.000054 | 暂无 | 170 秒 |
物相 / 状态
原因: 高于沸点（-61.7 °C）86.7 °C
示意图，未按比例绘制
相变点
相变能
在熔点熔化1 mol物质所需的能量
在沸点汽化1 mol物质所需的能量
密度
标准条件下
按当前温度T，通过理想气体定律估算
高级
原子光谱
已显示10项，共86项。 按离子电荷升序排列。
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| 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 |
暂无固相晶体结构数据
晶体结构: fcc
化合物
同位素 (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.
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 194 放射性 | 194.006144 ± 0.000018 | 暂无 | 780 us | α ≈100%β+ ? | |
| 217 放射性 | 217.003928 ± 0.0000045 | 暂无 | 593 us | α =100% | |
| 199 放射性 | 198.99839 ± 0.000068 | 暂无 | 590 ms | α ≈100%β+ ? | |
| 214 放射性 | 213.995363 ± 0.0000099 | 暂无 | 259 ns | α =100% | |
| 205 放射性 | 204.991719 ± 0.000054 | 暂无 | 170 秒 | β+ =75.4±0.9%α =24.6±0.9% |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 142 pm
- 共价半径（Pyykkö，双键）
- 145 pm
- 共价半径（Pyykkö，三键）
- 133 pm
范德华半径
- Truhlar
- 220 pm
- Alvarez
- 240 pm
- UFF
- 476.5 pm
- MM3
- 243 pm
原子半径与金属半径
- 原子半径（Rahm）
- 243 pm
编号标度
- Mendeleev
- 117
- Pettifor
- 6
- Glawe
- 6
电负性标度
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 4
极化率与色散
- 偶极极化率
- 35 a.u.
- 偶极极化率（不确定度）
- 2 a.u.
- C₆ (Gould–Bučko)
- 408 Ha·Bohr6
稀有气体性质
| HALOGENS | RnF2 |
相变与同素异形体
| 熔点 | 202.15 K |
| 沸点 | 211.45 K |
| 临界点（温度） | 377.15 K |
| 临界点（压力） | 6.28 MPa |
氧化态分类
高级参考数据
屏蔽常数 (15)
| n | 轨道 | 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 |
同位素衰变方式 (59)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 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射线散射因子 (516)
| 能量 (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 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
4×10-13 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
6×10-16 milligrams per liter
参考文献 (1)
参考文献
(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.