Astatine

Edit links
Source: Wikipedia, the free encyclopedia.

Astatine, 85At
Astatine
Pronunciation/ˈæstətiːn, -tɪn/ ​(ASS-tə-teen, -⁠tin)
Appearanceunknown, probably metallic
Mass number[210]
Astatine in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
 I 
↑
At
↓
Ts
polonium ← astatine → radon
Discovery
Dale R. Corson, Kenneth Ross MacKenzie, Emilio Segrè (1940)
Isotopes of astatine
Main isotopes[5] Decay
abun­dance half-life (t1/2) mode pro­duct
209At synth 5.41 h
β+
209Po
α
205Bi
210At synth 8.1 h β+ 210Po
α
206Bi
211At synth 7.21 h ε
211Po
α
207Bi
 Category: Astatine
| references

Astatine is a

radioactivity
.

The bulk properties of astatine are not known with certainty. Many of them have been estimated from its position on the

anionic species of astatine are known and most of its compounds resemble those of iodine, but it also sometimes displays metallic characteristics and shows some similarities to silver
.

The first synthesis of astatine was in 1940 by

Emilio G. Segrè at the University of California, Berkeley. They named it from the Ancient Greek ἄστατος (astatos) 'unstable'.[6] Four isotopes of astatine were subsequently found to be naturally occurring, although much less than one gram is present at any given time in the Earth's crust. Neither the most stable isotope, astatine-210, nor the medically useful astatine-211 occur naturally; they are usually produced by bombarding bismuth-209 with alpha particles
.

Characteristics

Astatine is an extremely radioactive element; all its isotopes have

half-lives of 8.1 hours or less, decaying into other astatine isotopes, bismuth, polonium, or radon. Most of its isotopes are very unstable, with half-lives of seconds or less. Of the first 101 elements in the periodic table, only francium is less stable, and all the astatine isotopes more stable than the longest-lived francium isotopes (205–211At) are in any case synthetic and do not occur in nature.[7]

The bulk properties of astatine are not known with any certainty.[8] Research is limited by its short half-life, which prevents the creation of weighable quantities.[9] A visible piece of astatine would immediately vaporize itself because of the heat generated by its intense radioactivity.[10] It remains to be seen if, with sufficient cooling, a macroscopic quantity of astatine could be deposited as a thin film.[4] Astatine is usually classified as either a nonmetal or a metalloid;[11][12] metal formation has also been predicted.[4][13]

Physical

Most of the physical properties of astatine have been estimated (by interpolation or extrapolation), using theoretically or empirically derived methods.[14] For example, halogens get darker with increasing atomic weight – fluorine is nearly colorless, chlorine is yellow-green, bromine is red-brown, and iodine is dark gray/violet. Astatine is sometimes described as probably being a black solid (assuming it follows this trend), or as having a metallic appearance (if it is a metalloid or a metal).[15][16][17]

Astatine sublimes less readily than iodine, having a lower

middle ultraviolet region has lines at 224.401 and 216.225 nm, suggestive of 6p to 7s transitions.[19][20]

The structure of solid astatine is unknown.

superconductor, like the similar high-pressure phase of iodine.[4] Metallic astatine is expected to have a density of 8.91–8.95 g/cm3.[1]

Evidence for (or against) the existence of diatomic astatine (At2) is sparse and inconclusive.

heat of vaporization (∆Hvap) 54.39 kJ/mol.[36] Many values have been predicted for the melting and boiling points of astatine, but only for At2.[37]

Chemical

The chemistry of astatine is "clouded by the extremely low concentrations at which astatine experiments have been conducted, and the possibility of reactions with impurities, walls and filters, or radioactivity by-products, and other unwanted nano-scale interactions".

monatomic cation in aqueous solution.[41][44]

Astatine has an

Allred–Rochow scale (1.9) being less than that of hydrogen (2.2).[49][c] However, official IUPAC stoichiometric nomenclature is based on an idealized convention of determining the relative electronegativities of the elements by the mere virtue of their position within the periodic table. According to this convention, astatine is handled as though it is more electronegative than hydrogen, irrespective of its true electronegativity. The electron affinity of astatine, at 233 kJ mol−1, is 21% less than that of iodine.[51] In comparison, the value of Cl (349) is 6.4% higher than F (328); Br (325) is 6.9% less than Cl; and I (295) is 9.2% less than Br. The marked reduction for At was predicted as being due to spin–orbit interactions.[39] The first ionization energy of astatine is about 899 kJ mol−1, which continues the trend of decreasing first ionization energies down the halogen group (fluorine, 1681; chlorine, 1251; bromine, 1140; iodine, 1008).[3]

Compounds

Main article: Astatine compounds

Less reactive than iodine, astatine is the least reactive of the halogens;[52] the chemical properties of tennessine, the next-heavier group 17 element, have not yet been investigated, however.[53] Astatine compounds have been synthesized in nano-scale amounts and studied as intensively as possible before their radioactive disintegration. The reactions involved have been typically tested with dilute solutions of astatine mixed with larger amounts of iodine. Acting as a carrier, the iodine ensures there is sufficient material for laboratory techniques (such as filtration and precipitation) to work.[54][55][d] Like iodine, astatine has been shown to adopt odd-numbered oxidation states ranging from −1 to +7.[58]

Only a few compounds with metals have been reported, in the form of astatides of sodium,[10] palladium, silver, thallium, and lead.[59] Some characteristic properties of silver and sodium astatide, and the other hypothetical alkali and alkaline earth astatides, have been estimated by extrapolation from other metal halides.[60]

Hydrogen astatide space-filling model

The formation of an astatine compound with hydrogen – usually referred to as

silver(I) iodide.[9][62]

Astatine is known to bind to

dative covalent bonds separately link the astatine(I) centre with each of the pyridine rings via their nitrogen atoms.[64]

With oxygen, there is evidence of the species AtO− and AtO+ in aqueous solution, formed by the reaction of astatine with an oxidant such as elemental bromine or (in the last case) by

dichromate; this is based on the observation that, in acidic solutions, monovalent or intermediate positive states of astatine coprecipitate with the insoluble salts of metal cations such as silver(I) iodate or thallium(I) dichromate.[66][73]

Astatine may form bonds to the other chalcogens; these include S7At+ and At(CSN)−2 with sulfur, a coordination selenourea compound with selenium, and an astatine–tellurium colloid with tellurium.[74]

Structure of astatine monoiodide, one of the astatine interhalogens and the heaviest known diatomic interhalogen

Astatine is known to react with its lighter homologs iodine,

mass spectrometer, the ions [AtI]+, [AtBr]+, and [AtCl]+ have been formed by introducing lighter halogen vapors into a helium-filled cell containing astatine, supporting the existence of stable neutral molecules in the plasma ion state.[56] No astatine fluorides have been discovered yet. Their absence has been speculatively attributed to the extreme reactivity of such compounds, including the reaction of an initially formed fluoride with the walls of the glass container to form a non-volatile product.[e] Thus, although the synthesis of an astatine fluoride is thought to be possible, it may require a liquid halogen fluoride solvent, as has already been used for the characterization of radon fluoride.[56][72]

History

Periodic table by Mendeleev (1871), with astatine missing below chlorine, bromine and iodine ("J")
Dmitri Mendeleev's table of 1871, with an empty space at the eka-iodine position

In 1869, when Dmitri Mendeleev published his periodic table, the space under iodine was empty; after Niels Bohr established the physical basis of the classification of chemical elements, it was suggested that the fifth halogen belonged there. Before its officially recognized discovery, it was called "eka-iodine" (from Sanskrit eka – "one") to imply it was one space under iodine (in the same manner as eka-silicon, eka-boron, and others).[82] Scientists tried to find it in nature; given its extreme rarity, these attempts resulted in several false discoveries.[83]

The first claimed discovery of eka-iodine was made by

radium series.[88] The properties he reported for dakin do not correspond to those of astatine,[88] and astatine's radioactivity would have prevented him from handling it in the quantities he claimed.[89] Moreover, astatine is not found in the thorium series, and the true identity of dakin is not known.[88]

In 1936, the team of Romanian physicist

IUPAC committee responsible for recognition of new elements. Even though Hulubei's samples did contain astatine-218, his means to detect it were too weak, by current standards, to enable correct identification; moreover, he could not perform chemical tests on the element.[89] He had also been involved in an earlier false claim as to the discovery of element 87 (francium) and this is thought to have caused other researchers to downplay his work.[90]

A greyscale photo of the upper body of a man
Emilio Segrè, one of the discoverers of the main-group element astatine

In 1940, the Swiss chemist Walter Minder announced the discovery of element 85 as the beta decay product of radium A (polonium-218), choosing the name "helvetium" (from Helvetia, the Latin name of Switzerland). Berta Karlik and Traude Bernert were unsuccessful in reproducing his experiments, and subsequently attributed Minder's results to contamination of his radon stream (radon-222 is the parent isotope of polonium-218).[91][f] In 1942, Minder, in collaboration with the English scientist Alice Leigh-Smith, announced the discovery of another isotope of element 85, presumed to be the product of thorium A (polonium-216) beta decay. They named this substance "anglo-helvetium",[92] but Karlik and Bernert were again unable to reproduce these results.[54]

Later in 1940,

neptunium series.[97]) Friedrich Paneth in 1946 called to finally recognize synthetic elements, quoting, among other reasons, recent confirmation of their natural occurrence, and proposed that the discoverers of the newly discovered unnamed elements name these elements. In early 1947, Nature published the discoverers' suggestions; a letter from Corson, MacKenzie, and Segrè suggested the name "astatine"[94] coming from the Ancient Greek αστατος (astatos) meaning 'unstable', because of its propensity for radioactive decay, with the ending "-ine", found in the names of the four previously discovered halogens. The name was also chosen to continue the tradition of the four stable halogens, where the name referred to a property of the element.[98]

Corson and his colleagues classified astatine as a metal on the basis of its

amphoteric behavior.[104][105] In a 2003 retrospective, Corson wrote that "some of the properties [of astatine] are similar to iodine ... it also exhibits metallic properties, more like its metallic neighbors Po and Bi."[98]

Isotopes

Main article: Isotopes of astatine
Alpha decay characteristics for sample astatine isotopes[g]
Mass
number 		Half-life[7] Probability
of alpha
decay[7] 		Alpha
decay
half-life
207 1.80 h 8.6% 20.9 h
208 1.63 h 0.55% 12.3 d
209 5.41 h 4.1% 5.5 d
210 8.1 h 0.175% 193 d
211 7.21 h 41.8% 17.2 h
212 0.31 s ≈100% 0.31 s
213 125 ns 100% 125 ns
214 558 ns 100% 558 ns
219 56 s 97% 58 s
220 3.71 min 8% 46.4 min
221 2.3 min experimentally
alpha stable 		∞

There are 41 known isotopes of astatine, with mass numbers of 188 and 190–229.[106][107] Theoretical modeling suggests that about 37 more isotopes could exist.[106] No stable or long-lived astatine isotope has been observed, nor is one expected to exist.[108]

Astatine's

beta-stable, as it has the lowest mass of all isobars with A = 215.[7] Astatine-210 and most of the lighter isotopes exhibit beta plus decay (positron emission), astatine-217 and heavier isotopes except astatine-218 exhibit beta minus decay, while astatine-211 undergoes electron capture.[5]

The most stable isotope is astatine-210, which has a half-life of 8.1 hours. The primary decay mode is beta plus, to the relatively long-lived (in comparison to astatine isotopes) alpha emitter polonium-210. In total, only five isotopes have half-lives exceeding one hour (astatine-207 to -211). The least stable ground state isotope is astatine-213, with a half-life of 125 nanoseconds. It undergoes alpha decay to the extremely long-lived bismuth-209.[7]

Astatine has 24 known nuclear isomers, which are nuclei with one or more nucleons (protons or neutrons) in an excited state. A nuclear isomer may also be called a "meta-state", meaning the system has more internal energy than the "ground state" (the state with the lowest possible internal energy), making the former likely to decay into the latter. There may be more than one isomer for each isotope. The most stable of these nuclear isomers is astatine-202m1,[i] which has a half-life of about 3 minutes, longer than those of all the ground states bar those of isotopes 203–211 and 220. The least stable is astatine-213m1; its half-life of 110 nanoseconds is shorter than 125 nanoseconds for astatine-213, the shortest-lived ground state.[5]

Natural occurrence

a sequence of differently colored balls, each containing a two-letter symbol and some numbers
Neptunium series, showing the decay products, including astatine-217, formed from neptunium-237

Astatine is the rarest naturally occurring element.[j] The total amount of astatine in the Earth's crust (quoted mass 2.36 × 1025 grams)[110] is estimated by some to be less than one gram at any given time.[9] Other sources estimate the amount of ephemeral astatine, present on earth at any given moment, to be up to one ounce[111] (about 28 grams).

Any astatine present at the formation of the Earth has long since disappeared; the four naturally occurring isotopes (astatine-215, -217, -218 and -219)

neptunium-237. The landmass of North and South America combined, to a depth of 16 kilometers (10 miles), contains only about one trillion astatine-215 atoms at any given time (around 3.5 × 10−10 grams).[113] Astatine-217 is produced via the radioactive decay of neptunium-237. Primordial remnants of the latter isotope—due to its relatively short half-life of 2.14 million years—are no longer present on Earth. However, trace amounts occur naturally as a product of transmutation reactions in uranium ores.[114] Astatine-218 was the first astatine isotope discovered in nature.[115] Astatine-219, with a half-life of 56 seconds, is the longest lived of the naturally occurring isotopes.[7]

Isotopes of astatine are sometimes not listed as naturally occurring because of misconceptions[104] that there are no such isotopes,[116] or discrepancies in the literature. Astatine-216 has been counted as a naturally occurring isotope but reports of its observation[117] (which were described as doubtful) have not been confirmed.[118]

Synthesis

Formation

Possible reactions after bombarding bismuth-209 with alpha particles
Reaction[k] Energy of alpha particle
209
83Bi + 4
2He → 211
85At + 2 1
0n 		26 MeV[54]
209
83Bi + 4
2He → 210
85At + 3 1
0n 		40 MeV[54]
209
83Bi + 4
2He → 209
85At + 4 1
0n 		60 MeV[119]

Astatine was first produced by bombarding bismuth-209 with energetic alpha particles, and this is still the major route used to create the relatively long-lived isotopes astatine-209 through astatine-211. Astatine is only produced in minuscule quantities, with modern techniques allowing production runs of up to 6.6 

nanograms or 2.47×1014 atoms). Synthesis of greater quantities of astatine using this method is constrained by the limited availability of suitable cyclotrons and the prospect of melting the target.[120][121][l] Solvent radiolysis due to the cumulative effect of astatine decay[123] is a related problem. With cryogenic technology, microgram quantities of astatine might be able to be generated via proton irradiation of thorium or uranium to yield radon-211, in turn decaying to astatine-211. Contamination with astatine-210 is expected to be a drawback of this method.[124]

The most important isotope is astatine-211, the only one in commercial use. To produce the bismuth target, the metal is

chemically neutral nitrogen atmosphere,[126] and is cooled with water to prevent premature astatine vaporization.[125] In a particle accelerator, such as a cyclotron,[127] alpha particles are collided with the bismuth. Even though only one bismuth isotope is used (bismuth-209), the reaction may occur in three possible ways, producing astatine-209, astatine-210, or astatine-211. In order to eliminate undesired nuclides, the maximum energy of the particle accelerator is set to a value (optimally 29.17 MeV)[128] above that for the reaction producing astatine-211 (to produce the desired isotope) and below the one producing astatine-210 (to avoid producing other astatine isotopes).[125]

Separation methods

Since astatine is the main product of the synthesis, after its formation it must only be separated from the target and any significant contaminants. Several methods are available, "but they generally follow one of two approaches—dry distillation or [wet] acid treatment of the target followed by solvent extraction." The methods summarized below are modern adaptations of older procedures, as reviewed by Kugler and Keller.[129][m] Pre-1985 techniques more often addressed the elimination of co-produced toxic polonium; this requirement is now mitigated by capping the energy of the cyclotron irradiation beam.[120]

Dry

The astatine-containing cyclotron target is heated to a temperature of around 650 °C. The astatine

volatilizes and is condensed in (typically) a cold trap. Higher temperatures of up to around 850 °C may increase the yield, at the risk of bismuth contamination from concurrent volatilization. Redistilling the condensate may be required to minimize the presence of bismuth[131] (as bismuth can interfere with astatine labeling reactions). The astatine is recovered from the trap using one or more low concentration solvents such as sodium hydroxide, methanol or chloroform. Astatine yields of up to around 80% may be achieved. Dry separation is the method most commonly used to produce a chemically useful form of astatine.[121][132]

Wet

The irradiated bismuth (or sometimes

bismuth nitrate to enable liquid–liquid extraction).[133][134] Wet methods involve "multiple radioactivity handling steps" and have not been considered well suited for isolating larger quantities of astatine. However, wet extraction methods are being examined for use in production of larger quantities of astatine-211, as it is thought that wet extraction methods can provide more consistency.[134] They can enable the production of astatine in a specific oxidation state and may have greater applicability in experimental radiochemistry.[120]

Uses and precautions

Several 211At-containing molecules and their experimental uses[135]
Agent Applications
[211At]astatine-tellurium colloids Compartmental tumors
6-[211At]astato-2-methyl-1,4-naphtaquinol diphosphate Adenocarcinomas
211At-labeled methylene blue Melanomas
Meta-[211At]astatobenzyl guanidine Neuroendocrine tumors
5-[211At]astato-2'-deoxyuridine Various
211At-labeled biotin conjugates Various pretargeting
211At-labeled octreotide Somatostatin receptor
211At-labeled monoclonal antibodies and fragments Various
211At-labeled
bisphosphonates
Bone metastases

Newly formed astatine-211 is the subject of ongoing research in

keV, enable the tracking of astatine in animals and patients.[135] Although astatine-210 has a slightly longer half-life, it is wholly unsuitable because it usually undergoes beta plus decay to the extremely toxic polonium-210.[137]

The principal medicinal difference between astatine-211 and iodine-131 (a radioactive iodine isotope also used in medicine) is that iodine-131 emits high-energy beta particles, and astatine does not. Beta particles have much greater penetrating power through tissues than do the much heavier alpha particles. An average alpha particle released by astatine-211 can travel up to 70 µm through surrounding tissues; an average-energy beta particle emitted by iodine-131 can travel nearly 30 times as far, to about 2 mm.[125] The short half-life and limited penetrating power of alpha radiation through tissues offers advantages in situations where the "tumor burden is low and/or malignant cell populations are located in close proximity to essential normal tissues."[120] Significant morbidity in cell culture models of human cancers has been achieved with from one to ten astatine-211 atoms bound per cell.[138]

Astatine ... [is] miserable to make and hell to work with.[139]

P Durbin, Human Radiation Studies: Remembering the Early Years, 1995

Several obstacles have been encountered in the development of astatine-based

monoclonal antibodies became available for this purpose. Unlike iodine, astatine shows a tendency to dehalogenate from molecular carriers such as these, particularly at sp3 carbon sites[n] (less so from sp2 sites). Given the toxicity of astatine accumulated and retained in the body, this emphasized the need to ensure it remained attached to its host molecule. While astatine carriers that are slowly metabolized can be assessed for their efficacy, more rapidly metabolized carriers remain a significant obstacle to the evaluation of astatine in nuclear medicine. Mitigating the effects of astatine-induced radiolysis of labeling chemistry and carrier molecules is another area requiring further development. A practical application for astatine as a cancer treatment would potentially be suitable for a "staggering" number of patients; production of astatine in the quantities that would be required remains an issue.[124][140][o]

Animal studies show that astatine, similarly to iodine—although to a lesser extent, perhaps because of its slightly more metallic nature

thyroid gland. Unlike iodine, astatine also shows a tendency to be taken up by the lungs and spleen, possibly because of in-body oxidation of At– to At+.[43] If administered in the form of a radiocolloid it tends to concentrate in the liver. Experiments in rats and monkeys suggest that astatine-211 causes much greater damage to the thyroid gland than does iodine-131, with repetitive injection of the nuclide resulting in necrosis and cell dysplasia within the gland.[141] Early research suggested that injection of astatine into female rodents caused morphological changes in breast tissue;[142] this conclusion remained controversial for many years. General agreement was later reached that this was likely caused by the effect of breast tissue irradiation combined with hormonal changes due to irradiation of the ovaries.[139] Trace amounts of astatine can be handled safely in fume hoods if they are well-aerated; biological uptake of the element must be avoided.[143]

See also

Notes

  1. ^ This half-vaporization period grows to 16 hours if it is instead put on a gold or platinum surface; this may be caused by poorly understood interactions between astatine and these noble metals.[18]
  2. ^ It is also possible that this is sorption on a cathode.[40]
  3. ^ The algorithm used to generate the Allred-Rochow scale fails in the case of hydrogen, providing a value that is close to that of oxygen (3.5). Hydrogen is instead assigned a value of 2.2. Despite this shortcoming, the Allred-Rochow scale has achieved a relatively high degree of acceptance.[50]
  4. ^ Iodine can act as a carrier despite it reacting with astatine in water because these reactions require iodide (I−), not (only) I2.[56][57]
  5. radon fluoride;[80] by this time, the latter had been shown to be ionic.[81]
  6. ^ In other words, some other substance was undergoing beta decay (to a different end element), not polonium-218.
  7. ^ In the table, "alpha decay half-life" refers to the half-life if decay modes other than alpha are omitted.
  8. ^ This means that, if decay modes other than alpha are omitted, then astatine-210 has an alpha decay half-life of 4,628.6 hours (128.9 days) and astatine-211 has one of only 17.2 hours (0.7 days). Therefore, astatine-211 is very much less stable toward alpha decay than astatine-210.
  9. ^ "m1" means that this state of the isotope is the next possible one above – with an energy greater than – the ground state. "m2" and similar designations refer to further higher energy states. The number may be dropped if there is only one well-established meta state, such as astatine-216m. Other designation techniques are sometimes used.
  10. ^ Emsley[10] states that this title has been lost to berkelium, "a few atoms of which can be produced in very-highly concentrated uranium-bearing deposits"; however, his assertion is not corroborated by any primary source.
  11. ^ A nuclide is commonly denoted by a symbol of the chemical element this nuclide belongs to, preceded by a non-spaced superscript mass number and a subscript atomic number of the nuclide located directly under the mass number. (Neutrons may be considered as nuclei with the atomic mass of 1 and the atomic charge of 0, with the symbol being n.) With the atomic number omitted, it is also sometimes used as a designation of an isotope of an element in isotope-related chemistry.
  12. ^ See however Nagatsu et al.[122] who encapsulate the bismuth target in a thin aluminium foil and place it in a niobium holder capable of holding molten bismuth.
  13. ^ See also Lavrukhina and Pozdnyakov.[130]
  14. ^ In other words, where carbon's one s atomic orbital and three p orbitals hybridize to give four new orbitals shaped as intermediates between the original s and p orbitals.
  15. ^ "Unfortunately, the conundrum confronting the … field is that commercial supply of 211At awaits the demonstration of clinical efficacy; however, the demonstration of clinical efficacy requires a reliable supply of 211At."[120]

References

  1. ^
    ISBN 978-1-62708-154-2
    .
  2. ISBN 978-0-08-037941-8
    .
  3. ^
    PMID 23673620
    .
  4. ^
    PMID 24074111
    .
  5. ^
    doi:10.1088/1674-1137/abddae
    .
  6. ^ "Astatine (At) | AMERICAN ELEMENTS ®". American Elements: The Materials Science Company. Retrieved 4 April 2024.
  7. ^
    doi:10.1016/j.nuclphysa.2003.11.001
    .
  8. ^ Greenwood & Earnshaw 2002, p. 795.
  9. ^
    ISBN 978-0-12-352651-9
    .
  10. ^
    ISBN 978-0-19-960563-7
    .
  11. ISBN 978-0-8400-4828-8
    .
  12. ISBN 978-1-4419-6314-7
    .
  13. ISBN 978-1-898563-71-6
    .
  14. ^ Maddock, A. G. (1956). "Astatine". Supplement to Mellor's Comprehensive Treatise on Inorganic and Theoretical Chemistry, Supplement II, Part 1, (F, Cl, Br, I, At). Longmans, Green & Co. (Ltd.). pp. 1064–1079.
  15. ^ Garrett, A. B.; Richardson, J. B.; Kiefer, A. S. (1961). Chemistry: A First Course in Modern Chemistry. Ginn. p. 313.
  16. ^ Seaborg, G. T. (2015). "Transuranium element". Encyclopædia Britannica. Retrieved 24 February 2015.
  17. ISBN 978-981-271-162-5
    .
  18. ^ Lavrukhina & Pozdnyakov 1970, p. 251.
  19. doi:10.1364/JOSA.54.000965
    .
  20. ^ Lavrukhina & Pozdnyakov 1970, p. 235.
  21. ISBN 978-0-89874-230-5
    .
  22. ^
    doi:10.1021/ed3008457
    .
  23. S2CID 96816296
    .
  24. ^ Merinis, J.; Legoux, G.; Bouissières, G. (1972). "Etude de la formation en phase gazeuse de composés interhalogénés d'astate par thermochromatographie" [Study of the gas-phase formation of interhalogen compounds of astatine by thermochromatography]. Radiochemical and Radioanalytical Letters (in French). 11 (1): 59–64.
  25. S2CID 93572282
    .
  26. ^ Takahashi, N.; Yano, D.; Baba, H. (1992). "Chemical Behavior of Astatine Molecules". Proceedings of the International Conference on Evolution in Beam Applications, Takasaki, Japan, 5–8 November 1991. pp. 536–539.
  27. ^ Zuckerman & Hagen 1989, p. 21.
  28. ^ Kugler & Keller 1985, pp. 110, 116, 210–211, 224.
  29. ISBN 978-0-12-227410-7
    .
  30. ISBN 978-3-527-30673-2
    .
  31. S2CID 100363889
    .
  32. ISBN 978-0-547-12532-9
    .
  33. ^
    ISBN 978-0-13-175553-6
    .
  34. ^ Kugler & Keller 1985, p. 116.
  35. doi:10.1063/1.471636
    .
  36. ^ Glushko, V. P.; Medvedev, V. A.; Bergma, G. A. (1966). Termicheskie Konstanty Veshchestv (in Russian). Vol. 1. Nakua. p. 65.
  37. ^ Kugler & Keller 1985, pp. 116–117.
  38. ^ Smith, A.; Ehret, W. F. (1960). College chemistry. Appleton-Century-Crofts. p. 457.
  39. ^
    PMID 21769335
    .
  40. S2CID 97361684
    .
  41. ^ a b Lavrukhina & Pozdnyakov 1970, p. 234.
  42. S2CID 93032218
    .
  43. ^
    PMID 23075373
    .
  44. S2CID 15738065
    .
  45. doi:10.1080/00268979100102951
    .
  46. doi:10.1016/S0009-2614(96)01250-X
    .
  47. ISBN 978-1-4020-9974-8
    .
  48. doi:10.1021/ed082p1721
    .
  49. ISBN 978-1-891389-01-6
    .
  50. ISBN 978-0-521-33738-0
    .
  51. PMID 32733029
    .
  52. doi:10.1146/annurev.ns.09.120159.001223
    . (subscription required)
  53. ^ "Superheavy Element 117 Confirmed – On the Way to the "Island of Stability"". GSI Helmholtz Centre for Heavy Ion Research. Archived from the original on 3 August 2018. Retrieved 26 July 2015.
  54. ^
    S2CID 250775410
    . (subscription required)
  55. doi:10.1039/AN9527700774
    . (subscription required)
  56. ^ a b c d e f Zuckerman & Hagen 1989, p. 31.
  57. ^ a b Zuckerman & Hagen 1989, p. 38.
  58. doi:10.1016/B978-0-323-91376-8.00012-4
    .
  59. ^ Kugler & Keller 1985, pp. 213–214.
  60. ^ Kugler & Keller 1985, pp. 214–218.
  61. ^ Kugler & Keller 1985, p. 211.
  62. ^ Kugler & Keller 1985, pp. 109–110, 129, 213.
  63. ISBN 978-0-85404-835-9
    .
  64. ^ a b c d Zuckerman & Hagen 1989, p. 276.
  65. ISBN 978-0-7817-9693-4
    .
  66. ^ a b c Zuckerman & Hagen 1989, pp. 190–191.
  67. doi:10.1021/om00059a071
    .
  68. ^ Kugler & Keller 1985, p. 111.
  69. PMID 26773333
    .
  70. ^ Kugler & Keller 1985, p. 222.
  71. ^ Lavrukhina & Pozdnyakov 1970, p. 238.
  72. ^ a b Kugler & Keller 1985, pp. 112, 192–193.
  73. ^ Kugler & Keller 1985, p. 219.
  74. ^ Zuckerman & Hagen 1989, pp. 192–193.
  75. ^ Zuckerman & Hagen 1990, p. 212.
  76. S2CID 99398848
    .
  77. ^ Zuckerman & Hagen 1990, p. 60.
  78. ^ Zuckerman & Hagen 1989, p. 426.
  79. doi:10.1021/ic50039a016
    .
  80. doi:10.1039/C3975000760B
    .
  81. ISBN 978-0-08-017275-0
    .
  82. ISBN 978-0-19-284100-1
    .
  83. ^ Lavrukhina & Pozdnyakov 1970, pp. 227–228.
  84. doi:10.1103/PhysRev.37.1178
    . (subscription required)
  85. ^ "Alabamine & Virginium". Time. 15 February 1932. Archived from the original on 30 September 2007.
  86. doi:10.1021/ed052p585
    . (subscription required)
  87. doi:10.1103/PhysRev.47.310
    .
  88. ^
    OCLC 13842122
    .
  89. ^ a b Burdette, S. C.; Thornton, B. F. (2010). "Finding Eka-Iodine: Discovery Priority in Modern Times" (PDF). Bulletin for the History of Chemistry. 35: 86–96. Archived (PDF) from the original on 9 October 2022.
  90. ISBN 978-0-19-539131-2
    .
  91. S2CID 6667655
    . (subscription required)
  92. S2CID 4121704
    . (subscription required)
  93. ^ Corson, MacKenzie & Segrè 1940.
  94. ^
    Science Service, Ballantine Books. p. 29. Archived from the original
    (PDF) on 23 August 2017. Retrieved 14 August 2016.
  95. S2CID 38193384
    . (subscription required)
  96. S2CID 123906708
    . (subscription required)
  97. John Wiley & Sons
    . pp. 1–657.
  98. ^
    doi:10.1021/cen-v081n036.p158
    .
  99. ^ Corson, MacKenzie & Segrè 1940, pp. 672, 677.
  100. PMID 16588388
    .
  101. doi:10.1016/0022-1902(57)80018-9
    .
  102. S2CID 95324453
    .
  103. ^ Dreyer, I.; Dreyer, R.; Chalkin, V. A. (1979). "Cations of Astatine in Aqueous Solutions; Production and some Characteristics". Radiochemical and Radioanalytical Letters (in German). 36 (6): 389–398.
  104. ^
    ISBN 978-0-12-023606-0
    .
  105. S2CID 250775410
    .
  106. ^
    S2CID 12590893
    .
  107. ^ Kokkonen, Henna. "Decay properties of the new isotopes 188At and 190At" (PDF). University of Jyväskylä. Retrieved 8 June 2023.
  108. ^ a b c d Lavrukhina & Pozdnyakov 1970, p. 229.
  109. ISBN 978-0-470-70800-2
    .
  110. ISBN 978-0-8493-0485-9
    .
  111. ^
    ISBN 0-19-508083-1
  112. ^ Lavrukhina & Pozdnyakov 1970, p. 228–229.
  113. ^ Asimov, I. (1957). Only a Trillion. Abelard-Schuman. p. 24.
  114. ^ Kolthoff, I. M.; Elving, P. J., eds. (1964). Treatise on Analytical Chemistry. Part II: Analytical Chemistry of the Elements. Vol. 4. New York: Interscience Encyclopedia. p. 487.
  115. ^ Kugler & Keller 1985, p. 4.
  116. S2CID 115321713
    .
  117. ^ Greenwood & Earnshaw 2002, p. 796.
  118. ^ Kugler & Keller 1985, p. 5.
  119. hdl:2027/mdp.39015086480574
    . (subscription required)
  120. ^
    PMID 22201707
    .
  121. ^
    PMID 8852627
    .
  122. PMID 25439168
    .
  123. ISBN 978-3-540-36718-5
    .
  124. ^
    PMID 11585866
    .
  125. ^ a b c d Lavrukhina & Pozdnyakov 1970, p. 233.
  126. ISBN 978-81-7371-660-7
    .
  127. ISBN 978-1-4020-8695-3
    .
  128. S2CID 21973246
    .
  129. ^ Kugler & Keller 1985, pp. 95–106, 133–139.
  130. ^ Lavrukhina & Pozdnyakov 1970, pp. 243–253.
  131. ^ Kugler & Keller 1985, p. 97.
  132. PMID 11393754
    .
  133. S2CID 93179195
    .
  134. ^
    ISSN 2076-3417
    .
  135. ^ a b c Vértes, Nagy & Klencsár 2003, p. 337.
  136. PMID 10903402
    .
  137. PMID 23422568
    .
  138. ^ Vértes, Nagy & Klencsár 2003, p. 338.
  139. ^ a b Fisher, D. (1995). "Oral History of Dr. Patricia Wallace Durbin, PhD". Human Radiation Studies: Remembering the Early Years. United States Department of Energy, Office of Human Radiation Experiments. Retrieved 25 March 2015.
  140. PMID 20150978
    .
  141. ^ Lavrukhina & Pozdnyakov 1970, pp. 232–233.
  142. ISBN 978-3-642-49477-2
    .
  143. ISBN 978-3527306732
    .

Bibliography

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Astatine&oldid=1217238405"