Astatine (At)
halogenSolid
标准原子量
[210]电子排布
[Xe] 6s2 4f14 5d10 6p5熔点
301.85 °C沸点
暂无密度
7000 kg/m³氧化态
−1, +1, +3, +5, +7电负性（鲍林）
2.2第一电离能
9.31751 eV发现年份
1940原子半径
暂无详细信息
Astatine is a very rare, highly radioactive halogen below iodine in group 17. All of its isotopes are unstable, and only minute amounts occur naturally as short-lived products in uranium and thorium decay chains. Its chemistry is partly experimental and partly inferred from periodic trends, because usable quantities are extremely small. Astatine shows both halogen-like behavior and unusually metallic character for a halogen.
The "time of flight" mass spectrometer has been used to confirm that this highly radioactive halogen behaves chemically very much like other halogens, particularly iodine. Astatine is said to be more metallic than iodine, and, like iodine, it probably accumulates in the thyroid gland. Workers at the Brookhaven National Laboratory have recently used reactive scattering in crossed molecular beams to identify and measure elementary reactions involving astatine.
Astatine was produced by Dale R. Carson, K.R. MacKenzie and Emilio Segrè by bombarding an isotope of bismuth, bismuth-209, with alpha particles that had been accelerated in a device called a cyclotron. This created astatine-211 and two free neutrons. This work was conducted at the University of California in 1940. Small amounts of astatine exist in nature as a result of the decay of uranium and thorium, although the total amount of astatine in the earth's crust at any particular time is less than 30 grams. Due to its scarcity, astatine is produced when it is needed. A total of 0.05 micrograms (0.00000005 grams) of astatine have been produced to date.
Astatine's most stable isotope, astatine-210, has a half-life of 8.1 hours. It decays into bismuth-206 through alpha decay or into polonium-210 through electron capture.
From the Greek astatos meaning unstable. Synthesized in 1940 by D.R. Corson, K.R. MacKenzie, and E. Segre at the University of California by bombarding bismuth with alpha particles. The longest-lived isotopes, with naturally occurring uranium and thorium isotopes, and traces of 217At are equilibrium with 233U and 239Np resulting from integration of thorium and uranium with naturally produced neutrons. The total amount of astatine present in the earth's crust, however, is less than 1 oz.
The bulk appearance of astatine has not been directly observed in a macroscopic sample. It is usually handled atom-by-atom or in ultratrace solution. A dark solid, possibly with metallic character, is predicted from periodic trends but is not an experimentally established description.
Astatine has no commercial use as an element. Its main practical interest is in nuclear medicine research, especially ²¹¹At for targeted alpha-particle therapy studies. This isotope can be attached to carrier molecules that seek selected biological targets, but its short half-life and difficult production limit routine use. Other uses are confined to radiochemical research, tracer-scale studies of heavy halogen chemistry, and isotope-production development.
Due to the small amounts produced and its short half-life, there are currently no uses for astatine outside of basic scientific research.
Isotopes in Medicine
211At (with a half-life of 7.2 h) is known to accumulate in the thyroid and occasionally is the preferred treatment for hyperthyroidism and thyroid cancer because the particles emitted from 211At provide more energy than radiolabeled iodine, the other treatment method (Fig. IUPAC.85.1). However, astatine has shown a tendency to induce tumors, so its use is limited [565] L. M. Cobb, A. Harrison, N. E. Dudley, T. E. F. Carr, J. A. Humphreys. Radiother. Oncol.13, 203 (1988).. The 211At-labeled di-carborane (cluster of boron, carbon, and hydrogen atoms) ligand known as the Venus Flytrap Cluster (VFC) has been used as a robust pharmaceutical in radiotherapy treatment [566] J. T. Gullon. “The preparation of metallocarborane and iodinated carborane amino acid analogues for molecular imaging and therapy”, S. dissertation, Dept. of Chemistry, McMaster University, Hamilton, Ontario, Canada (2010). http://hdl.handle.net/11375/9362..
Astatine chemistry is dominated by tracer-scale studies, so many compounds are identified by behavior rather than by isolating bulk material. It can form astatide ions, At⁻, and interhalogen or pseudohalogen-like species. Oxidation states from −1 to positive states such as +1, +3, +5, and possibly +7 are discussed, depending strongly on medium and ligand. Species such as hydrogen astatide, HAt, and astatine monoiodide, AtI, are known or inferred in small-scale studies. Organ astatine compounds with carbon–astatine bonds are important in radiolabeling research.
See more information at the Astatine compound page.
Astatine hazards are dominated by radioactivity, not ordinary chemical toxicity data. Isotope-specific half-lives and decay modes matter; ²¹¹At is an alpha emitter, while other isotopes may have different radiation signatures. Even tiny masses can require shielding, containment, remote handling, and contamination control. Chemical toxicity is poorly characterized because quantities are far below conventional toxicological testing levels.
Natural astatine exists only transiently in trace quantities within radioactive decay chains, mainly associated with uranium- and thorium-bearing minerals. Its atoms decay before they can accumulate or take part in a substantial geochemical cycle. Environmental behavior is therefore inferred from halogen chemistry and radiochemical experiments rather than observed at bulk scale. Releases of artificial astatine would be controlled primarily by its short-lived radioactivity and chemical form.
Astatine has no commodity market and is not mined as a product. Research quantities, especially ²¹¹At, are produced in particle accelerators, commonly by bombarding bismuth targets and then rapidly separating the product. Supply is constrained by isotope half-life, specialized cyclotron access, target processing, transport time, and radiochemical infrastructure. Recycling is not meaningful in the usual industrial sense because the isotopes decay quickly and are used in tracer or medical-research amounts.
Does not occur in nature. Similar to iodine. Produced by bombarding bismuth with alpha particles.
Astatine is not a significant cosmic reservoir element. Any astatine formed in stellar nucleosynthesis or radioactive decay is short-lived on geological and astronomical timescales, so it does not persist in detectable bulk abundance. In planetary materials it can appear only as a temporary daughter product of heavier radioactive nuclides.
- Astatine is usually studied in quantities far below a visible speck.
- The longest-lived known astatine isotopes still have half-lives of only hours.
- The name comes from a Greek word meaning unstable.
- ²¹¹At is valued in research because alpha particles travel only short distances in tissue.
- Astatine can behave less like a simple halogen than iodine does, especially in positive oxidation states.
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
- 202 pm 比较所有元素的范德华半径 →
- 密度
- 7000 kg/m³ 比较所有元素的密度 →
- 标准温度和压力下的物相
- 固态 比较所有元素的标准温度和压力下的物相 →
- 熔点
- 301.85 °C 比较所有元素的熔点 →
化学性质
- 电负性（鲍林）
- 2.2 比较所有元素的电负性（鲍林） →
- 电负性（Allen）
- 2.39
- 电子亲和能
- 2.391 eV
- 第一电离能
- 9.31751 eV 比较所有元素的第一电离能 →
- 第二电离能
- 17.880062 eV 比较所有元素的第二电离能 →
- 第三电离能
- 26.580091 eV 比较所有元素的第三电离能 →
- 第四电离能
- 39.650136 eV 比较所有元素的第四电离能 →
- 第五电离能
- 50.390173 eV 比较所有元素的第五电离能 →
- 氧化态
- −1, +1, +3, +5, +7 比较所有元素的氧化态 →
- 价电子
- 7 比较所有元素的价电子 →
- 电子排布
- [Xe] 6s2 4f14 5d10 6p5
热力学性质
- 熔化热
- 0.06218583 eV 比较所有元素的熔化热 →
- 汽化热
- 0.41457221 eV 比较所有元素的汽化热 →
- 升华热
- 1.554646 eV
- 原子化热
- 1.554646 eV
核性质
- 质子
- 85 比较所有元素的质子 →
- 中子
- 125 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）
- 210
- 最稳定同位素
- At-210
- 发现年份
- 1940
丰度
暂无
晶体结构
暂无
电子结构
- 各电子层电子数
- 2, 8, 18, 32, 18, 7 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 7440-68-8 比较所有元素的CAS登记号 →
- 谱项符号
- 2P°3/2
- InChI
- InChI=1S/At
- InChI Key
- RYXHOMYVWAEKHL-UHFFFAOYSA-N
电子排布 实测值
At: 4f¹⁴ 5d¹⁰ 6s² 6p⁵[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁵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 |
|---|---|---|---|
| 214 放射性 | 213.9963721 ± 0.0000046 | 暂无 | 558 ns |
| 197 放射性 | 196.993189 ± 0.000055 | 暂无 | 388.2 ms |
| 196 放射性 | 195.9958 ± 0.000033 | 暂无 | 377 ms |
| 212 放射性 | 211.9907377 ± 0.0000026 | 暂无 | 314 ms |
| 216 放射性 | 216.0024236 ± 0.0000039 | 暂无 | 300 us |
物相 / 状态
原因: 低于熔点（301.85 °C）276.9 °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
在升华点升华1 mol物质所需的能量
密度
标准条件下
标准条件下
原子光谱
已显示10项，共85项。 按离子电荷升序排列。
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| At I | 0 | 4 |
| At II | +1 | 2 |
| At III | +2 | 2 |
| At IV | +3 | 2 |
| At V | +4 | 2 |
| At VI | +5 | 2 |
| At VII | +6 | 2 |
| At VIII | +7 | 2 |
| At IX | +8 | 2 |
| At X | +9 | 2 |
暂无晶体结构数据
离子半径
| 电荷 | 配位 | 自旋 | 半径 |
|---|---|---|---|
| +7 | 6 | 暂无 | 62 pm |
化合物
同位素 (5)
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 214 放射性 | 213.9963721 ± 0.0000046 | 暂无 | 558 ns | α =100% | |
| 197 放射性 | 196.993189 ± 0.000055 | 暂无 | 388.2 ms | α =96.1±1.2%β+ =3.9±1.2% | |
| 196 放射性 | 195.9958 ± 0.000033 | 暂无 | 377 ms | α =97.5±0.3%β+ ?β+SF =0.009±0.1% | |
| 212 放射性 | 211.9907377 ± 0.0000026 | 暂无 | 314 ms | α ≈100%β+ ?β- ? | |
| 216 放射性 | 216.0024236 ± 0.0000039 | 暂无 | 300 us | α ≈100%β- ?ε ? |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 147 pm
- 共价半径（Pyykkö，双键）
- 138 pm
- 共价半径（Pyykkö，三键）
- 138 pm
范德华半径
- Truhlar
- 202 pm
- UFF
- 475 pm
- MM3
- 251 pm
原子半径与金属半径
- 原子半径（Rahm）
- 247 pm
编号标度
- Mendeleev
- 110
- Pettifor
- 96
- Glawe
- 98
电负性标度
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 7
- Robles–Bartolotti
- 6
极化率与色散
- 偶极极化率
- 42 a.u.
- 偶极极化率（不确定度）
- 4 a.u.
- C₆ (Gould–Bučko)
- 351 Ha·Bohr6
相变与同素异形体
| 熔点 | 575.15 K |
氧化态分类
高级参考数据
屏蔽常数 (15)
| n | 轨道 | σ |
|---|---|---|
| 1 | s | 1.6446 |
| 2 | p | 4.5524 |
| 2 | s | 22.3324 |
| 3 | d | 13.4155 |
| 3 | p | 23.5024 |
| 3 | s | 24.6481 |
| 4 | d | 37.9504 |
| 4 | f | 37.7596 |
| 4 | p | 36.516 |
| 4 | s | 35.6644 |
晶体半径详情 (1)
| 电荷 | CN | 自旋 | rcrystal (pm) | 来源 |
|---|---|---|---|---|
| 7 | VI | 76 | Ahrens (1952) ionic radius, |
同位素衰变方式 (76)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 191 | A | 100% |
| 191 | B+ | — |
| 192 | A | 100% |
| 192 | B+ | — |
| 192 | B+SF | 0.5% |
| 193 | A | 100% |
| 194 | A | 100% |
| 194 | B+ | 8.3% |
| 194 | B+SF | 0% |
| 195 | A | 100% |
X射线散射因子 (516)
| 能量 (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 8.78144 |
| 10.1617 | — | 8.87321 |
| 10.3261 | — | 8.96593 |
| 10.4931 | — | 9.04836 |
| 10.6628 | — | 9.08532 |
| 10.8353 | — | 9.12244 |
| 11.0106 | — | 9.1597 |
| 11.1886 | — | 9.1933 |
| 11.3696 | — | 9.15142 |
| 11.5535 | — | 9.10973 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
参考文献 (1)
- [5] Astatine https://education.jlab.org/itselemental/ele085.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (1)
- [5] Astatine https://education.jlab.org/itselemental/ele085.html
Production
Production of this element (from raw materials or other compounds containing the element).
Astatine can be produced by bombarding bismuth with energetic alpha particles to obtain the relatively long-lived 209-211At, which can be distilled from the target by heating in air.
参考文献 (1)
- [6] Astatine https://periodic.lanl.gov/85.shtml
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 Astatine.
The element property data was retrieved from publications.