Astatine
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211At- and 131I-labeled bisphosphonates with high in vivo stability and bone accumulation. (1/53)
Bisphosphonates were synthesized for use as carriers for astatine and iodine radioisotopes to target bone neoplasms. METHODS: Radiohalogenated activated esters were coupled to the amino group in the side chain of the bisphosphonate. The bisphosphonate 3-amino-1-hydroxypropylidene bisphosphonate was combined with four different acylation agents: N-succinimidyl 3-[211At]astatobenzoate, N-succinimidyl 3-[131I]iodobenzoate, N-succinimidyl-5-[211At]astato-3-pyridinecarboxylate and N-succinimidyl-5-[131I]iodo-5-pyridinecarboxylate. The products, 3-[131I]iodobenzamide-N-3-hydroxypropylidene-3,3-bisphosphonate (IBPB), 3-[211At]astato-benzamide-N-3-hydroxypropylidene-3,3-bisphosphonat e (ABPB), 5-[131I]iodopyridine-3-amide-N-3-hydroxypropylidene-3,3-bisphospho nate (IPPB) and 5-[211At]astatopyridine-3-amide-N-3-hydroxypropylidene-3,3-bisphos phonate (APPB), were injected intravenously into Balb/c mice. MIRD and Monte Carlo methods were used on the basis of cumulated activity calculated from biodistribution data to estimate dose to organs and bone segments. RESULTS: All 131I- and 211At-labeled analogs were strongly incorporated into osseous tissue and retained there at stable levels, while a rapid clearance from blood was observed. The bone uptake was found to be similar for 211At- and 131I-labeled bisphosphonate when compared in paired label experiments. Bone uptake and bone-to-tissue ratios were better for IBPB compared with IPPB, and ABPB compared with APPB. All four compounds appeared to be highly resistant to in vivo dehalogenation as indicated by low uptake of 131I/211At in the thyroid gland and stomach. According to dosimetric estimates, the bone surface-to-bone marrow ratio was three times higher with 211At than with 131I. CONCLUSION: Both the beta-particle- and alpha-particle-emitting compounds showed high in vivo stability and excellent affinity for osseous tissue. Further preclinical evaluation is therefore warranted. (+info)Demonstration of highly specific toxicity of the alpha-emitting radioimmunoconjugate(211)At-rituximab against non-Hodgkin's lymphoma cells. (2/53)
The ability of an alpha-emitter conjugated to a chimaeric anti-CD20 monoclonal antibody to kill selectively human B-lymphoma cells in vitro is reported. Two B-lymphoma cell lines RAEL and K422, and normal haematopoietic progenitor cells from human bone marrow aspirates were incubated with(211)At-rituximab (Rituxan(R) or MabTheratrade mark) and plated in clonogenic assays for survival analyses. Following 1 h incubation with(211)At-rituximab, in concentrations which gave an initial activity of 50 kBq ml(-1), a high tumour cell to normal bone marrow cell toxicity ratio was obtained; 4.1 to 1.0 log cell kill. Biodistribution studies of(211)At-rituximab in Balb/c mice showed similar stability as that of the iodinated analogue. The data indicate that testing of(211)At-rituximab in human patients is warranted. (+info)High-level production of alpha-particle-emitting (211)At and preparation of (211)At-labeled antibodies for clinical use. (3/53)
In vitro and in vivo studies in human glioma models suggest that the antitenascin monoclonal antibody 81C6 labeled with the 7.2-h-half-life alpha-particle emitter (211)At might be a valuable endoradiotherapeutic agent for the treatment of brain tumors. The purpose of this study was to develop methods for the production of high levels of (211)At and the radiosynthesis of clinically useful amounts of (211)At-labeled human/mouse chimeric 81C6 antibody. METHODS: (211)At was produced through the (209)Bi(alpha, 2n)(211)At reaction using an internal target system and purified by a dry distillation process. Antibody labeling was accomplished by first synthesizing N-succinimidyl 3-[(211)At]astatobenzoate from the corresponding tri-n-butyl tin precursor and reacting it with the antibody in pH 8.5 borate buffer. Quality control procedures consisted of methanol precipitation, size-exclusion high-performance liquid chromatography (HPLC), and pyrogen and sterility assays, as well as determination of the immunoreactive fraction by a rapid procedure using a recombinant tenascin fragment coupled to magnetic beads. RESULTS: A total of 16 antibody labeling runs were performed. Using beam currents of 50-60 microA alpha-particles and irradiation times of 1.5-4.5 h, the mean (211)At production yield was 27.75 +/- 2.59 MBq/microA.h, and the maximum level of (211)At produced was 6.59 GBq after a 4-h irradiation at 55 microA. The decay-corrected distillation yield was 67% +/- 16%. The yield for the coupling of the (211)At-labeled active ester to the antibody was 76% +/- 8%. The fraction of (211)At activity that eluted with a retention time corresponding to intact IgG on HPLC was 96.0% +/- 2.5%. All preparations had a pyrogen level of <0.125 EU/mL and were determined to be sterile. The mean immunoreactive fraction for these 16 preparations was 83.3% +/- 5.3%. Radiolysis did not interfere with labeling chemistry or the quality of the labeled antibody product. CONCLUSION: These results show that it is feasible to produce clinically relevant activities of (211)At-labeled antibodies and have permitted the initiation of a phase I trial of (211)At-labeled chimeric 81C6 administered directly into the tumor resection cavities of brain tumor patients. (+info)Comparative cellular catabolism and retention of astatine-, bismuth-, and lead-radiolabeled internalizing monoclonal antibody. (4/53)
Monoclonal antibodies (mAbs) labeled with alpha-emitting radionuclides such as (211)At, (212)Bi, (213)Bi, and (212)Pb (which decays by beta-emission to its alpha-emitting daughter, (212)Bi) are being evaluated for their potential applications for cancer therapy. The fate of these radionuclides after cells are targeted with mAbs is important in terms of dosimetry and tumor detection. METHODS: In this study, we attached various radionuclides that result in alpha-emissions to T101, a rapidly internalizing anti-CD5 mAb. We then evaluated the catabolism and cellular retention and compared them with those of (125)I- and (111)In-labeled T101. T101 was labeled with (211)At, (125)I, (205,6)Bi, (111)In, and (203)Pb. CD5 antigen-positive cells, peripheral blood mononuclear cells (PBMNC), and MOLT-4 leukemia cells were used. The labeled T101 was incubated with the cells for 1 h at 4 degrees C for surface labeling. Unbound activity was removed and 1 mL medium added. The cells were then incubated at 37 degrees C for 0, 1, 2, 4, 8, and 24 h. The activity on the cell surface that internalized and the activity on the cell surface remaining in the supernatant were determined. The protein in the supernatant was further precipitated by methanol for determining protein-bound and non-protein-bound radioactivity. Sites of internal cellular localization of radioactivity were determined by Percoll gradient centrifugation. RESULTS: All radiolabeled antibodies bound to the cells were internalized rapidly. After internalization, (205,6)Bi, (203)Pb, and (111)In radiolabels were retained in the cell, with little decrease of cell-associated radioactivity. However, (211)At and (125)I were released from cells rapidly ((211)At < (125)I) and most of the radioactivity in the supernatant was in a non-protein-bound form. Intracellular distribution of radioactivity revealed a transit of the radiolabel from the cell surface to the lysosome. The catabolism patterns of MOLT-4 cells and PBMNC were similar. CONCLUSION: (211)At catabolism and release from cells were somewhat similar to that of (125)I, whereas (205,6)Bi and (203)Pb showed prolonged cell retention similar to that of (111)In. These catabolism differences may be important in the selection of alpha-radionuclides for radioimmunotherapy. (+info)Microdosimetric analysis of alpha-particle-emitting targeted radiotherapeutics using histological images. (5/53)
The purpose of this study was to evaluate the therapeutic efficacy and limitations of alpha-particle-emitting radiolabeled compounds by means of 2-dimensional histological images and distribution of activity on a microscopic level. METHODS: A microdosimetric approach based on histological images is used to analyze the therapeutic effectiveness of alpha-particle-emitting (211)At and (213)Bi conjugated to 201B monoclonal antibody (mAb), which is reactive with murine lung blood vessels for the treatment of EMT-6 lung tumor colonies in nude mice. Autoradiography images were used to define the tissue morphology and activity distribution within lung tissues. Two animal groups were studied: Group A consisted of animals bearing small tumors (<130 micro m) and group B consisted of larger tumors (<600 micro m). Probability density functions (pdf) described the variability in average absorbed dose and survival probability among normal and tumor target cells and, in turn, were used to assess the survival fraction of tumor and normal tissue. RESULTS: The average absorbed dose to tumor cells per unit cumulated activity concentration for animals in group A was 1.10 x 10(-3) and 1.37 x 10(-3) Gy g MBq(-1) s(-1) for (211)At and (213)Bi, respectively, and for animals in group B was 3.8 x 10(-4) and 5.6 x 10(-4) Gy g MBq(-1) s(-1) for (211)At and (213)Bi, respectively. The fraction of tumor cells that received a zero absorbed dose for animals in group A was 0.04% for (213)Bi and 0.2% for (211)At and for animals in group B was 25% for (213)Bi and 31% for (211)At. Both (213)Bi- and (211)At-labeled 201B mAb were effective therapies for animals with small tumors, where predicted therapeutic effectiveness was consistent with experimental findings; however, they were ineffective for animals with larger tumors. CONCLUSION: Microdosimetric methods based on knowledge of tissue morphology and activity distribution on a small-scale level can be a useful tool for evaluating a priori the therapeutic efficacy and limitations of targeted alpha-particle endoradiotherapeutic strategies. (+info)(211)At-labeled and biotinylated effector molecules for pretargeted radioimmunotherapy using poly-L- and poly-D-Lysine as multicarriers. (6/53)
Poly-L- and poly-D-lysine were evaluated as carriers of astatine and biotin for prospective use as effector molecules in pretargeted radioimmunotherapy of micrometastases. The precursor polylysine was derivatized in a three-step, single-pot procedure, including biotinylation with biotin amidocaproic N-hydroxysuccinimide, astatination via the intermediate reagent N-succinimidyl 3-(trimethylstannyl)benzoate, and, finally, charge modification using succinic anhydride. The chemistry was shown to be very facile, with a biotinylation efficiency of 75 +/- 5%, and overall radiochemical yields in the range of 50-70%. After charge modification, no amines could be detected in the final product. The biotin function was unaffected by the chemistry and the radiation, as confirmed by almost complete binding of the effector molecule to avidin beads using a convenient filter tube assay. The effector molecules were evaluated in tumor-free female nude mice with regard to whole-body retention and tissue distribution after i.p. administration. The distribution of the L-isomer effector molecule showed rapid whole-body clearance with low uptake in all tissues, whereas the D-isoform showed whole-body clearance related to uptake in the kidneys. Both D-isomer and L-isomer showed faster blood clearance and generally lower tissue uptakes than labeled antibodies. The normal tissue distribution after the peritoneal administration implies that pretargeting using L-structure polylysine as the effector molecule may give a higher therapeutic index than that achieved in conventional radioimmunotherapy. (+info)Astatine-211-labeled antibodies for treatment of disseminated ovarian cancer: an overview of results in an ovarian tumor model. (7/53)
PURPOSE: The aim of the study was to establish and refine a preclinical model to alpha-immunoradiotherapy of ovarian cancer. EXPERIMENTAL DESIGN: At-211 was produced by cyclotron irradiation of a bismuth-209 target and isolated using a novel dry distillation procedure. Monoclonal antibodies were radiohalogenated with the intermediate reagent N-succinimidyl 3-(trimethylstannyl)benzoate and characterized in terms of radiochemical yield and in vitro binding properties. In vitro OVCAR-3 cells were irradiated using an external Cobalt-60 beam, as reference, or At-211-albumin and labeled antibody. Growth assays were used to establish cell survival. A Monte Carlo program was developed to simulate the energy imparted and the track length distribution. Nude mice were used for studies of WBC depression, with various activities of Tc-99m antibodies, as reference, and At-211 antibodies. In efficacy studies, OVCAR-3 cells were inoculated i.p., and animals were treated 2 weeks later. The animals were either dissected 6 weeks later or followed-up for long-term survival. RESULTS: A rapid distillation procedure, as well as a rapid and high-yield, single-pot labeling procedure, was achieved. From growth inhibition data, the relative biological effectiveness of the alpha-emission for OVCAR-3 cells was estimated to be approximately 5, which is in the same range as found in vivo for hematological toxicity. At-211 MOv18 was found to effectively inhibit the development of tumors and ascites, also resulting in long-term survival without significant toxic effect. CONCLUSIONS: Use of the short-range, high-linear energy transfer alpha-emitter At-211 conjugated to a surface epitope-recognizing monoclonal antibody appears to be highly efficient without significant toxicity in a mouse peritoneal tumor model, urging a Phase I clinical trial. (+info)In vitro cytotoxicity of (211)at-astatide and (131)I-iodide to glioma tumor cells expressing the sodium/iodide symporter. (8/53)
The sodium/iodide symporter (NIS) has been identified as an attractive target for cancer therapy. The efficacy of (131)I-iodide for NIS-expressing tumor therapy may be limited by a combination of poor cellular retention and unfavorable physical characteristics (long physical half-life and low linear-energy-transfer [LET] radiative emissions). On the other hand, (211)At-astatide is also transported by NIS and offers several therapeutic advantages over (131)I-iodide due to its physical characteristics (short half-life, high LET alpha-particle emissions). The objective of this study was to directly compare the radiotoxicity of both radionuclides using a NIS-transfected cultured cell model. METHODS: Cytotoxicity was determined by colony-forming assays. Also, a first-order pharmacokinetic model was used to simulate the closed compartmental system between the medium and cells. Experimental data were then fitted to this model and used to estimate the transfer coefficients between medium and cells, k(m)(c), and between cells and medium, k(c)(m). Using the pharmacokinetic model, the cumulated activity concentrations in the medium and cells were calculated. Monte Carlo transport methods were then used to assess absorbed doses from (131)I and (211)At. RESULTS: (211)At-Astatide was significantly more cytotoxic than (131)I-iodide in this closed compartmental system. For (211)At-astatide, absorbed doses per unit administered activity were 54- to 65-fold higher than for (131)I-iodide. Both NIS-expressing and control cells showed increased sensitivity to (211)At over (131)I, with significantly lower D(0) (absorbed dose required to reduce the survival fraction to e(-1)) and SF(2) (2-Gy survival fraction) values, highlighting the higher intrinsic cytotoxicity of alpha-particles. However, NIS-independent (nonspecific) binding of (211)At-astatide was higher than that of (131)I-iodide, therefore, yielding a lower absorbed dose ratio between NIS-transfected and -nontransfected cells. CONCLUSION: Treatment of NIS-expressing cells with (211)At-astatide resulted in higher absorbed doses and increased cytotoxicity per unit administered activity than that observed with (131)I-iodide. These results suggest that (211)At-astatide may be a promising treatment strategy for the therapy of NIS-expressing tumors. (+info)
Astatine - Wikipedia
Application of astatine-210: Evaluation of astatine distribution and effect of pre-injected iodide in whole body of normal rats...
Periodic Table of Elements: Astatine - At (EnvironmentalChemistry.com)
Periodic Table Element Comparison | Compare Copper vs Astatine | Compare Properties, Structure, Facts
BIOETYMOLOGY : ORIGIN IN BIOMEDICAL TERMS: astatine (At)
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Alice Leigh-Smith
In 1942, Leigh-Smith and a Swiss chemist, Walter Minder jointly announced the discovery of element 85 (now called astatine) in ... Nefedov, VD; Norseev, Yu V; Toropova, M A; Khalkin, Vladimir A (1968). "Astatine". Russian Chemical Reviews. 37 (2): 87. ...
Timeline of chemical element discoveries
"85 Astatine". Elements.vanderkrogt.net. Retrieved 2008-09-12. Close, Frank E. (2004). Particle Physics: A Very Short ...
Chemical element
In some presentations, the halogens are not distinguished, with astatine identified as a metalloid and the others identified as ... Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; ... The remaining 6 transient elements (technetium, promethium, astatine, francium, neptunium, and plutonium) occur only rarely, as ... astatine, francium, actinium, and protactinium), and Various synthetic transuranic elements, beginning with americium and ...
Tennessine
Astatine's 6p subshell split is only 3.8 eV, and its 6p1/2 chemistry has already been called "limited". These effects cause ... A later paper predicts the boiling point of tennessine to be 345 °C (that of astatine is estimated as 309 °C, 337 °C, or 370 °C ... For comparison, the figure for hydrogen-like astatine is 1.27 and the figure for hydrogen-like iodine is 1.08. Simple ... With the seven outermost electrons removed, tennessine is finally smaller; 57 pm for tennessine and 61 pm for astatine. The ...
Chang Kang-myoung
... 아스타틴 Astatine), Epiclog, 2017. Uriui sowoneun jeonjaeng (우리의 소원은 전쟁 Our wish is war), Wisdom House, 2016. Daetgeulbudae (댓글부대 ...
Interhalogen
Astatine monoiodide (AtI) is made by direct combination of astatine and iodine. No astatine fluorides have been discovered yet ... Astatine monochloride (AtCl) is made either by the direct combination of gas-phase astatine with chlorine or by the sequential ... Astatine monobromide (AtBr) is made by the direct combination of astatine with either bromine vapour or an aqueous solution of ... Those formed with astatine have a very short half-life due to astatine being intensely radioactive. No interhalogen compounds ...
Metal ions in aqueous solution
Calculations for polonium(IV) indicate a solvation number between 8 and 9. Arsenic(III) and astatine(I) do not seem to form ... Astatine', System No. 8a. Gmelin Handbook of Inorganic and Organometallic Chemistry. 8 (8th ed.). Springer-Verlag. pp. 220-221 ... aqua cations: arsenic(III) is calculated to form hydrolyzed species only, and electromigration evidence shows that astatine(I) ...
Iodine
Astatine goes further, being indeed unstable as At− and readily oxidised to At0 or At+, although the existence of At2 is not ... The fifth and sixth halogens, the radioactive astatine and tennessine, are not well-studied due to their expense and ... This trend occurs because the wavelengths of visible light absorbed by the halogens increase down the group (though astatine ... 800-4 Kugler, H. K.; Keller, C. (1985). 'At, Astatine', System No. 8a. Gmelin Handbook of Inorganic and Organometallic ...
Polyiodide
King, R. Bruce (2005). "Chlorine, Bromine, Iodine, & Astatine: Inorganic Chemistry". Encyclopedia of Inorganic Chemistry (2nd ...
Electron affinity (data page)
2020). "The electron affinity of astatine". Nat. Commun. 11: 3824. doi:10.1038/s41467-020-17599-2. Landau, A.; Eliav, E.; ...
AB
Alabamine, a former name of Astatine. AB Class amplifier, a classification of electric amplifier The category of abelian groups ...
Maryanne Ito
The group, dubbed The Astatine Collective, consists of Freeze as DJ, Sub Z on MPC and audio engineering, Deesarono as a ... CS1 maint: discouraged parameter (link) Hitt, Christine (October 25, 2014). "Maryanne Ito and the Astatine Collective". ... and in October 2014 she and local group The Astatine Collective performed at Hallowbaloo. She was also a performer at the Great ... She has toured Hawaii with The Astatine Collective as support, and in the summer of 2015 she toured Europe, performing at ...
Period 6 element
Attempts to synthesize astatine fluoride have been met with failure. The second longest-living astatine-211 is the only one to ... the most stable astatine-210 and the industrially used astatine-211 are not. Radon is a chemical element with symbol Rn and ... astatine is the least abundant element in Earth's crust among non-transuranium elements. Among astatine isotopes, six (with ... Astatine is a radioactive chemical element with the symbol At and atomic number 85. It occurs on the Earth only as the result ...
Polyhalogen ions
Astatine: Inorganic Chemistry". Encyclopedia of Inorganic Chemistry (2nd ed.). Wiley. p. 747. ISBN 9780470862100. Housecroft, ...
Halogen
These isotopes are astatine-215, astatine-217, and astatine-219. A total of 31 isotopes of astatine have been discovered, with ... Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium ... There are no stable isotopes of astatine. However, there are three naturally occurring radioactive isotopes of astatine ... Astatine has no biological role.[4] Toxicity[edit]. The halogens tend to decrease in toxicity towards the heavier halogens.[30] ...
Standard atomic weight
Asta-tine85At[210] Radon86Rn[222] 7 Fran-cium87Fr[223] Ra-dium88Ra[226] Actin-ium89Ac[227] Ruther-fordium104Rf[267] Dub- ...
Metalloid
... it has been presumed that astatine would be a metal if it could form a condensed phase. Astatine may be metallic in the liquid ... complexes of astatine cations ... complex anions of trivalent astatine ... as well as complexes with a variety of organic ... A further option is to include astatine both as a nonmetal and as a metalloid. A visible piece of astatine would be immediately ... Astatine has an IE of 215 kJ/mol (899 kJ/mol) and an EN of 2.2. Its electronic band structure is not known with any certainty. ...
Kenneth Ross MacKenzie
"Kenneth MacKenzie, 90; Helped Discover Astatine, Built UCLA's Atom Smasher". "In Memoriam" (PDF). UCLA Today. 22 (5). October ... synthesized the element astatine, in 1940. MacKenzie received his PhD under Ernest Lawrence at Lawrence Livermore National ...
Ununennium
Astatine, and Francium. Translated by R. Kondor. Ann Arbor-Humphrey Science Publishers. p. 269. ISBN 978-0-250-39923-9. Jones, ...
Francium
The only comparable element is astatine, whose most stable natural isotope, astatine-219 (the alpha daughter of francium-223), ... after astatine). The isotopes of francium decay quickly into astatine, radium, and radon. The electronic structure of a ... All isotopes of francium decay into astatine, radium, or radon. Francium-223 also has a shorter half-life than the longest- ... Francium-221 then decays into astatine-217 by alpha decay (6.457 MeV decay energy). The least stable ground state isotope is ...
Boron group
Astatine, the heaviest halogen, has only formed a few compounds, due to its radioactivity and short half-life, and no reports ... Cite journal requires ,journal= (help) Roza, Greg (2010). The Halogen Elements: Fluorine, Chlorine, Bromine, Iodine, Astatine. ...
Nonmetal
Bulk astatine has been predicted to have a metallic face-centred cubic structure † Hydrogen can also form alloy-like hydrides ... Astatine was synthesised in 1940 by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè. They bombarded bismuth-209 with ... In scheme (1), the halogens are in a category of their own; astatine is classed as a nonmetal, rather than a metalloid; and the ... Astatine has been predicted to have a metallic crystalline structure. Chemically the metalloids generally behave like (weak) ...
Melting points of the elements (data page)
Astatine, and Francium. Translated by R. Kondor. Ann Arbor-Humphrey Science Publishers. p. 269. ISBN 978-0-250-39923-9. Not ...
Lists of metalloids
The status of polonium and astatine is not settled. Most authors recognise one or the other, or both, as metalloids; Herman, ... 1686-87, doi:10.1021/ed078p1686 Holt, Rinehart & Wilson c. 2007 'Why polonium and astatine are not metalloids in HRW texts', ... 8, p. 783, doi:10.1021ed100308w Hermann A, Hoffmann R & Ashcroft NW 2013, 'Condensed Astatine: Monatomic and Metallic', ... Hoffmann and Ashcroft, on the basis of relativistic modelling, predict astatine will be a monatomic metal. One or more of ...
Compounds of fluorine
Astatine is not well-studied, and although there is a report of a non-volatile astatine monofluoride, its existence is debated ... All of the elements up to einsteinium, element 99, have been checked except for astatine and francium, and fluorine is also ... Gmelin, Leopold (1985-07-03). Gmelin handbook of inorganic chemistry: At-Astatine (8th ed.). Springer-Verlag. p. 224. ISBN ...
Radon-222
Fry, C.; Thoennessen, M. (2013). "Discovery of the astatine, radon, francium, and radium isotopes". Atomic Data and Nuclear ...
Post-transition metal
... astatine was predicted to be a monatomic metal, with a face-centered cubic crystalline structure.[177] As such, astatine could ... Astatine oxyanions AtO−, AtO−. 3 and AtO−. 4 are known,[182] oxyanion formation being a tendency of nonmetals.[183] The ... Kugler HK & Keller C (eds) 1985, Gmelin Handbook of Inorganic and Organometallic chemistry, 8th ed., 'At, Astatine', system no ... Hawkes SJ 2010, 'Polonium and Astatine are not Semimetals', Journal of Chemical Education, vol. 87, no. 8, p. 783, doi:10.1021 ...
Carbon group
Tin forms dihalides and tetrahalides with all halogens except astatine. Tin forms chalcogenides with one of each naturally ... Germanium forms tetrahalides with all halogens except astatine and forms dihalides with all halogens except bromine and ... astatine. Germanium bonds to all natural single chalcogens except polonium, and forms dioxides, disulfides, and diselenides. ...
Metals close to the border between metals and nonmetals
The hydroxide of astatine At(OH) is presumed to be amphoteric. Astatine forms covalent compounds with nonmetals, including ... Astatine is a radioactive element that has never been seen; a visible quantity would immediately be vaporised due to its ... Astatine is commonly regarded as a nonmetal, less commonly as a metalloid and occasionally as a metal. Unlike its lighter ... As such, astatine could be expected to have a metallic appearance; show metallic conductivity; and have excellent ductility, ...
Halogen
These isotopes are astatine-215, astatine-217, astatine-218, and astatine-219. A total of 31 isotopes of astatine have been ... There are no stable isotopes of astatine. However, there are four naturally occurring radioactive isotopes of astatine produced ... Astatine, although very scarce, has been found in micrograms in the earth. Tennessine is purely man-made and has no other roles ... Astatine is very radioactive and thus highly dangerous, but it has not been produced in macroscopic quantities and hence it is ...