Astatine (At)
halogenSolid
표준 원자량
[210]전자 배치
[Xe] 6s2 4f14 5d10 6p5녹는점
301.85 °C끓는점
해당 없음밀도
7000 kg/m³산화 상태
−1, +1, +3, +5, +7전기 음성도(Pauling)
2.2제1 이온화 에너지
9.31751 eV발견 연도
1940원자 반지름
해당 없음상세 정보
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.
이미지
특성
물리적 특성
- 공유 결합 반지름
- 150 pm 모든 원소의 공유 결합 반지름 비교 →
- 반데르발스 반지름
- 202 pm 모든 원소의 반데르발스 반지름 비교 →
- 밀도
- 7000 kg/m³ 모든 원소의 밀도 비교 →
- STP에서의 상
- 고체 모든 원소의 STP에서의 상 비교 →
- 녹는점
- 301.85 °C 모든 원소의 녹는점 비교 →
화학적 특성
- 전기 음성도(Pauling)
- 2.2 모든 원소의 전기 음성도(Pauling) 비교 →
- 전기 음성도(Allen)
- 2.39
- 전자 친화도
- 2.391 eV
- 제1 이온화 에너지
- 9.31751 eV 모든 원소의 제1 이온화 에너지 비교 →
- 제2 이온화 에너지
- 17.880062 eV 모든 원소의 제2 이온화 에너지 비교 →
- 제3 이온화 에너지
- 26.580091 eV 모든 원소의 제3 이온화 에너지 비교 →
- 제4 이온화 에너지
- 39.650136 eV 모든 원소의 제4 이온화 에너지 비교 →
- 제5 이온화 에너지
- 50.390173 eV 모든 원소의 제5 이온화 에너지 비교 →
- 산화 상태
- −1, +1, +3, +5, +7 모든 원소의 산화 상태 비교 →
- 원자가 전자
- 7 모든 원소의 원자가 전자 비교 →
- 전자 배치
- [Xe] 6s2 4f14 5d10 6p5
열역학적 특성
- 융해열
- 0.06218583 eV 모든 원소의 융해열 비교 →
- 기화열
- 0.41457221 eV 모든 원소의 기화열 비교 →
- 승화열
- 1.554646 eV
- 원자화열
- 1.554646 eV
핵 특성
- 양성자 수
- 85 모든 원소의 양성자 수 비교 →
- 중성자 수
- 125 모든 원소의 중성자 수 비교 →
- 알려진 동위원소 수
- 39 모든 원소의 알려진 동위원소 수 비교 →
- 안정 동위원소 수
- 0 모든 원소의 안정 동위원소 수 비교 →
- 질량수(가장 안정한 동위원소)
- 210
- 가장 안정한 동위원소
- At-210
- 발견 연도
- 1940
존재비
해당 없음
결정 구조
해당 없음
전자 구조
- 전자껍질별 전자 수
- 2, 8, 18, 32, 18, 7 모든 원소의 전자껍질별 전자 수 비교 →
식별자
- CAS 등록 번호
- 7440-68-8 모든 원소의 CAS 등록 번호 비교 →
- 항 기호
- 2P°3/2
- InChI
- InChI=1S/At
- InChI 키
- RYXHOMYVWAEKHL-UHFFFAOYSA-N
전자 배치 측정값
At: 4f¹⁴ 5d¹⁰ 6s² 6p⁵[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁵원자 모형
동위원소에 따라 중성자 수, 질량, 안정성은 달라지지만, 중성 원자의 전자 배치는 달라지지 않습니다.
개략적인 원자 모형이며 실제 비율과 다릅니다.
원자 지문
방출 / 흡수 스펙트럼
동위원소 분포
안정 동위원소가 없습니다.
| 질량수 | 원자 질량(u) | 천연 존재비 | 반감기 |
|---|---|---|---|
| 214 방사성 | 213.9963721 ± 0.0000046 | 해당 없음 | 558 ns |
| 197 방사성 | 196.993189 ± 0.000055 | 해당 없음 | 388.2 ms |
| 196 방사성 | 195.9958 ± 0.000033 | 해당 없음 | 377 ms |
| 212 방사성 | 211.9907377 ± 0.0000026 | 해당 없음 | 314 ms |
| 216 방사성 | 216.0024236 ± 0.0000039 | 해당 없음 | 300 us |
상 / 상태
이유: 녹는점(301.85 °C)보다 276.9 °C 낮음
개략도이며 실제 비율과 다름
상전이점
전이 에너지
녹는점에서 1 mol을 녹이는 데 필요한 에너지
끓는점에서 1 mol을 기화시키는 데 필요한 에너지
승화점에서 1 mol을 승화시키는 데 필요한 에너지
밀도
표준 조건에서
표준 조건에서
원자 스펙트럼
전체 85개 중 10개를 표시합니다. 이온 전하순으로 정렬되었습니다(오름차순).
보유 에너지 준위 데이터 ?
| 이온 | 전하 | 준위 |
|---|---|---|
| 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 |
결정 구조 데이터 없음
이온 반지름
| 전하 | 배위 | 스핀 | 반지름 |
|---|---|---|---|
| +7 | 6 | 해당 없음 | 62 pm |
화합물
동위원소 (5)
| 질량수 | 원자 질량(u) | 천연 존재비 | 반감기 | 붕괴 방식 | |
|---|---|---|---|---|---|
| 214 방사성 | 213.9963721 ± 0.0000046 | 해당 없음 | 558 ns | α =100% | |
| 197 방사성 | 196.993189 ± 0.000055 | 해당 없음 | 388.2 ms | α =96.1±1.2%β+ =3.9±1.2% | |
| 196 방사성 | 195.9958 ± 0.000033 | 해당 없음 | 377 ms | α =97.5±0.3%β+ ?β+SF =0.009±0.1% | |
| 212 방사성 | 211.9907377 ± 0.0000026 | 해당 없음 | 314 ms | α ≈100%β+ ?β- ? | |
| 216 방사성 | 216.0024236 ± 0.0000039 | 해당 없음 | 300 us | α ≈100%β- ?ε ? |
확장 특성
공유 결합 반지름(확장)
- 공유 결합 반지름(Pyykkö)
- 147 pm
- 공유 결합 반지름(Pyykkö, 이중 결합)
- 138 pm
- 공유 결합 반지름(Pyykkö, 삼중 결합)
- 138 pm
반데르발스 반지름
- Truhlar
- 202 pm
- UFF
- 475 pm
- MM3
- 251 pm
원자 및 금속 반지름
- 원자 반지름(Rahm)
- 247 pm
번호 척도
- Mendeleev
- 110
- Pettifor
- 96
- Glawe
- 98
전기 음성도 척도
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 7
- Robles–Bartolotti
- 6
분극률 및 분산
- 쌍극자 분극률
- 42 a.u.
- 쌍극자 분극률(불확도)
- 4 a.u.
- C₆ (Gould–Bučko)
- 351 Ha·Bohr6
상전이 및 동소체
| 녹는점 | 575.15 K |
산화 상태 분류
심화 참고 데이터
차폐 상수 (15)
| n | 오비탈 | 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 |
결정 반지름 상세 정보 (1)
| 전하 | CN | 스핀 | rcrystal (pm) | 기원 |
|---|---|---|---|---|
| 7 | VI | 76 | Ahrens (1952) ionic radius, |
동위원소 붕괴 방식 (76)
| 동위원소 | 모드 | 세기 |
|---|---|---|
| 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% |
X선 산란 인자 (516)
| 에너지 (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 |
추가 데이터
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
참고 문헌 (1)
- [5] Astatine https://education.jlab.org/itselemental/ele085.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
참고 문헌 (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.
참고 문헌 (1)
- [6] Astatine https://periodic.lanl.gov/85.shtml
참고 문헌
(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.