Astatine (At)
halogenSolid
Bobot Atom Standar
[210]Konfigurasi elektron
[Xe] 6s2 4f14 5d10 6p5Titik lebur
301,85 °CTitik didih
Tidak tersediaMassa jenis
7000 kg/m³Bilangan oksidasi
−1, +1, +3, +5, +7Keelektronegatifan (Pauling)
2,2Energi ionisasi (ke-1)
9,31751 eVTahun penemuan
1940Jari-jari atom
Tidak tersediaDetail
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.
Gambar
Sifat
Fisika
- Jari-jari kovalen
- 150 pm Bandingkan Jari-jari kovalen semua unsur →
- Jari-jari van der Waals
- 202 pm Bandingkan Jari-jari van der Waals semua unsur →
- Massa jenis
- 7000 kg/m³ Bandingkan Massa jenis semua unsur →
- Fase pada STP
- Padat Bandingkan Fase pada STP semua unsur →
- Titik lebur
- 301,85 °C Bandingkan Titik lebur semua unsur →
Kimia
- Keelektronegatifan (Pauling)
- 2,2 Bandingkan Keelektronegatifan (Pauling) semua unsur →
- Keelektronegatifan (Allen)
- 2,39
- Afinitas elektron
- 2,391 eV
- Energi ionisasi (ke-1)
- 9,31751 eV Bandingkan Energi ionisasi (ke-1) semua unsur →
- Energi ionisasi (ke-2)
- 17,880062 eV Bandingkan Energi ionisasi (ke-2) semua unsur →
- Energi ionisasi (ke-3)
- 26,580091 eV Bandingkan Energi ionisasi (ke-3) semua unsur →
- Energi ionisasi (ke-4)
- 39,650136 eV Bandingkan Energi ionisasi (ke-4) semua unsur →
- Energi ionisasi (ke-5)
- 50,390173 eV Bandingkan Energi ionisasi (ke-5) semua unsur →
- Bilangan oksidasi
- −1, +1, +3, +5, +7 Bandingkan Bilangan oksidasi semua unsur →
- Elektron valensi
- 7 Bandingkan Elektron valensi semua unsur →
- Konfigurasi elektron
- [Xe] 6s2 4f14 5d10 6p5
Termodinamika
- Kalor peleburan
- 0,06218583 eV Bandingkan Kalor peleburan semua unsur →
- Kalor penguapan
- 0,41457221 eV Bandingkan Kalor penguapan semua unsur →
- Kalor sublimasi
- 1,554646 eV
- Kalor atomisasi
- 1,554646 eV
Nuklir
- Proton
- 85 Bandingkan Proton semua unsur →
- Neutron
- 125 Bandingkan Neutron semua unsur →
- Isotop yang diketahui
- 39 Bandingkan Isotop yang diketahui semua unsur →
- Isotop stabil
- 0 Bandingkan Isotop stabil semua unsur →
- Nomor massa (paling stabil)
- 210
- Isotop paling stabil
- At-210
- Tahun penemuan
- 1940
Kelimpahan
Tidak tersedia
Struktur Kristal
Tidak tersedia
Struktur Elektronik
- Elektron per kulit
- 2, 8, 18, 32, 18, 7 Bandingkan Elektron per kulit semua unsur →
Pengenal
- Nomor CAS
- 7440-68-8 Bandingkan Nomor CAS semua unsur →
- Simbol term
- 2P°3/2
- InChI
- InChI=1S/At
- Kunci InChI
- RYXHOMYVWAEKHL-UHFFFAOYSA-N
Konfigurasi Elektron Diukur
At: 4f¹⁴ 5d¹⁰ 6s² 6p⁵[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d¹⁰ 6s² 6p⁵Model atom
Isotop mengubah jumlah neutron, massa, dan kestabilan — bukan konfigurasi elektron atom netral.
Model atom skematis, tidak sesuai skala.
Sidik Jari Atom
Spektrum Emisi / Absorpsi
Distribusi Isotop
Tidak memiliki isotop stabil.
| Nomor massa | Massa atom (u) | Kelimpahan alami | Waktu paruh |
|---|---|---|---|
| 214 Radioaktif | 213,9963721 ± 0,0000046 | Tidak tersedia | 558 ns |
| 197 Radioaktif | 196,993189 ± 0,000055 | Tidak tersedia | 388.2 ms |
| 196 Radioaktif | 195,9958 ± 0,000033 | Tidak tersedia | 377 ms |
| 212 Radioaktif | 211,9907377 ± 0,0000026 | Tidak tersedia | 314 ms |
| 216 Radioaktif | 216,0024236 ± 0,0000039 | Tidak tersedia | 300 us |
Fase / Wujud
Alasan: 276,9 °C di bawah titik lebur (301,85 °C)
Skematis, tidak sesuai skala
Titik transisi fase
Energi transisi
Energi yang diperlukan untuk meleburkan 1 mol pada titik lebur
Energi yang diperlukan untuk menguapkan 1 mol pada titik didih
Energi yang diperlukan untuk menyublimkan 1 mol pada titik sublimasi
Massa jenis
Pada kondisi standar
Pada kondisi standar
Spektrum Atom
Menampilkan 10 dari 85. Diurutkan berdasarkan muatan ion (menaik).
Data Garis Spektrum ?
| Ion | Muatan | Total garis | Probabilitas transisi | Penamaan tingkat energi |
|---|---|---|---|---|
| At I | 0 | 2 | 0 | 2 |
Data Tingkat Energi ?
| Ion | Muatan | Tingkat energi |
|---|---|---|
| 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 |
Data struktur kristal tidak tersedia
Jari-jari Ion
| Muatan | Koordinasi | Spin | Jari-jari |
|---|---|---|---|
| +7 | 6 | Tidak tersedia | 62 pm |
Senyawa
Isotop (5)
| Nomor massa | Massa atom (u) | Kelimpahan alami | Waktu paruh | Mode peluruhan | |
|---|---|---|---|---|---|
| 214 Radioaktif | 213,9963721 ± 0,0000046 | Tidak tersedia | 558 ns | α =100% | |
| 197 Radioaktif | 196,993189 ± 0,000055 | Tidak tersedia | 388.2 ms | α =96.1±1.2%β+ =3.9±1.2% | |
| 196 Radioaktif | 195,9958 ± 0,000033 | Tidak tersedia | 377 ms | α =97.5±0.3%β+ ?β+SF =0.009±0.1% | |
| 212 Radioaktif | 211,9907377 ± 0,0000026 | Tidak tersedia | 314 ms | α ≈100%β+ ?β- ? | |
| 216 Radioaktif | 216,0024236 ± 0,0000039 | Tidak tersedia | 300 us | α ≈100%β- ?ε ? |
Sifat Lanjutan
Jari-jari Kovalen (Lanjutan)
- Jari-jari kovalen (Pyykkö)
- 147 pm
- Jari-jari kovalen (Pyykkö, ikatan rangkap dua)
- 138 pm
- Jari-jari kovalen (Pyykkö, ikatan rangkap tiga)
- 138 pm
Jari-jari van der Waals
- Truhlar
- 202 pm
- UFF
- 475 pm
- MM3
- 251 pm
Jari-jari Atom & Logam
- Jari-jari atom (Rahm)
- 247 pm
Skala Penomoran
- Mendeleev
- 110
- Pettifor
- 96
- Glawe
- 98
Skala Keelektronegatifan
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 7
- Robles–Bartolotti
- 6
Polarizabilitas & Dispersi
- Polarizabilitas dipol
- 42 a.u.
- Polarizabilitas dipol (ketidakpastian)
- 4 a.u.
- C₆ (Gould–Bučko)
- 351 Ha·Bohr6
Transisi Fase & Alotrop
| Titik lebur | 575,15 K |
Kategori Bilangan Oksidasi
Data Referensi Lanjutan
Konstanta Pemerisaian (15)
| n | Orbital | 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 |
Detail Jari-jari Kristal (1)
| Muatan | CN | Spin | rcrystal (pm) | Asal |
|---|---|---|---|---|
| 7 | VI | 76 | Ahrens (1952) ionic radius, |
Mode Peluruhan Isotop (76)
| Isotop | Mode | Intensitas |
|---|---|---|
| 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% |
Faktor Hamburan Sinar-X (516)
| Energi (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 |
Data Tambahan
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
Referensi (1)
- [5] Astatine https://education.jlab.org/itselemental/ele085.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
Referensi (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.
Referensi (1)
- [6] Astatine https://periodic.lanl.gov/85.shtml
Referensi
(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.