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Encyclopedia > Astatine
85 poloniumastatineradon
I

At

(Uus)
General
Name, Symbol, Number astatine, At, 85
Chemical series halogens
Group, Period, Block 17, 6, p
Appearance metallic (presumed)
Standard atomic weight (210) g·mol−1
Electron configuration [Xe] 4f14 5d10 6s2 6p5
Electrons per shell 2, 8, 18, 32, 18, 7
Physical properties
Phase solid
Melting point 575 K
(302 °C, 576 °F)
Boiling point  ? 610 K
(? 337 °C, ? 639 °F)
Heat of vaporization ca. 40 kJ·mol−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 361 392 429 475 531 607
Atomic properties
Crystal structure no data
Oxidation states ±1, 3, 5, 7
Electronegativity 2.2 (scale Pauling)
Ionization energies 1st: 890±40 kJ/mol
Miscellaneous
Magnetic ordering no data
Thermal conductivity (300 K) 1.7 W·m−1·K−1
CAS registry number 7440-68-8
Selected isotopes
Main article: Isotopes of astatine
iso NA half-life DM DE (MeV) DP
210At 100% 8.1 h ε, β+ 3.981 210Po
α 5.631 206Bi
References

Astatine (IPA: /ˈastətiːn/) is a chemical element in the periodic table that has the symbol At and atomic number 85. This radioactive element occurs naturally from uranium-235 and uranium-238 decay; it is the heaviest of the halogens. General Name, Symbol, Number polonium, Po, 84 Chemical series metalloids Group, Period, Block 16, 6, p Appearance silvery Standard atomic weight (209) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p4 Electrons per shell 2, 8, 18, 32, 18, 6 Physical properties Phase solid Density (near r. ... For other uses, see Radon (disambiguation). ... For the record label, see Iodine Recordings. ... Predicted properties Name, Symbol, Number Ununseptium, Uus, 117 Chemical series Presumably Halogens Group, Period, Block 17, 7 , p Appearance unknown, but probably metallic and dark in appearance Atomic weight [291] amu (a guess) Electron configuration [Rn] 5f14 6d10 7s27p5 (a guess based upon astatine) e-s per energy level 2... By Greatpatton. ... This is a standard display of the periodic table of the elements. ... An extended periodic table was suggested by Glenn T. Seaborg in 1969. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... A table of chemical elements ordered by atomic number and color coded according to type of element. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... This article is about the chemical series. ... A group, also known as a family, is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a horizontal row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... The halogens are a chemical series. ... A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the elements, including the Lanthanides. ... The p-block of the periodic table of elements consists of the last six groups. ... Color is an important part of the visual arts. ... The atomic mass (ma) is the mass of an atom at rest, most often expressed in unified atomic mass units. ... To help compare different orders of magnitude we list here masses between 60. ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Standard atomic weight 131. ... For other uses, see Electron (disambiguation). ... Example of a sodium electron shell model An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... For other uses, see Solid (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ... For other uses, see Kelvin (disambiguation). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... For other uses, see Fahrenheit (disambiguation). ... Italic text This article is about the boiling point of liquids. ... For other uses, see Kelvin (disambiguation). ... Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ... For other uses, see Fahrenheit (disambiguation). ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... The joule per mole (symbol: J·mol-1) is an SI derived unit of energy per amount of material. ... Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The oxidation number of an element in a molecule or complex is the charge that it would have if all the ligands (basically, atoms that donate electrons) were removed along with the electron pairs that were shared with the central atom[1]. It means that the oxidation number is the... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... The ionization energy (IE) of an atom or of a molecule is the energy required to strip it of an electron. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... For other senses of this word, see magnetism (disambiguation). ... K value redirects here. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Astatine (At) Has no stable isotopes. ... For other uses, see Isotope (disambiguation). ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... The decay energy is the energy released by a nuclear decay. ... The electronvolt (symbol eV) is a unit of energy. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... The hour (symbol: h) is a unit of time. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... Positron emission is a type of beta decay, sometimes referred to as beta plus (β+). In beta plus decay, a proton is converted to a neutron via the weak nuclear force and a beta plus particle (a positron) and a neutrino are emitted. ... General Name, Symbol, Number polonium, Po, 84 Chemical series metalloids Group, Period, Block 16, 6, p Appearance silvery Standard atomic weight (209) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p4 Electrons per shell 2, 8, 18, 32, 18, 6 Physical properties Phase solid Density (near r. ... Alpha decay Alpha decay is a type of radioactive decay in which an atom emits an alpha particle (two protons and two neutrons bound together into a particle identical to a helium nucleus) and transforms (or decays) into an atom with a mass number 4 less and atomic number 2... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous reddish white Atomic mass 208. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... The Periodic Table redirects here. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... General Name, symbol, number uranium, U, 92 Chemical series actinides Group, period, block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... This article is about the chemical series. ...

Contents

Notable characteristics

This highly radioactive element has been confirmed by mass spectrometers to behave chemically much like other halogens, especially iodine (it would probably accumulate in the thyroid gland like iodine). Astatine is thought to be more metallic than iodine. Researchers at the Brookhaven National Laboratory have performed experiments that have identified and measured elementary reactions that involve astatine; however, chemical research into astatine is limited by its extreme rarity, which is a result of its extremely short half-life. Its most stable isotope has a half-life of around 8.3 hours. The final product of the decay of astatine is an isotope of lead. Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Mass spectrometry is a technique for separating ions by their mass-to-charge (m/z) ratios. ... This article is about the chemical series. ... For the record label, see Iodine Recordings. ... This article is about metallic materials. ... ≠ Aerial view of Brookhaven National Laboratory. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... This article is about the metal. ...


Astatine is the rarest naturally-occurring element, with the total amount in Earth's crust estimated to be less than 1 oz (28 g) at any given time; this amounts to less than one teaspoon of the element. The Guinness Book of Records has dubbed the element the rarest on Earth, stating: "Only around 0.9 oz (25 g) of the element astatine (At) occurring naturally"; Isaac Asimov, in a 1957 essay on large numbers, scientific notation, and the size of the atom, wrote that in "all of North and South America to a depth of ten miles", the number of astatine atoms at any time was "only a trillion".[1] The ounce (abbreviation: oz) is the name of a unit of mass in a number of different systems, including various systems of mass that form part of English units, Imperial units, and United States customary units. ... Suresh Joachim, minutes away from breaking the ironing world record at 55 hours and 5 minutes, at Shoppers World, Brampton. ... BIC pen cap, about 1 gram. ... Isaac Asimov (January 2?, 1920?[1] – April 6, 1992), IPA: , originally Исаак Озимов but now transcribed into Russian as Айзек Азимов) was a Russian-born American Jewish author and professor of biochemistry, a highly successful and exceptionally prolific writer best known for his works of science fiction and for his popular science books. ... Only a Trillion is a collection of ten science essays and three scientific spoof articles by Isaac Asimov. ... Big numbers redirects here. ... Scientific notation, also known as standard form, is a notation for writing numbers that is often used by scientists and mathematicians to make it easier to write large and small numbers. ... One million million (1,000,000,000,000) is the natural number following 999,999,999,999 and preceding 1,000,000,000,001. ...


History

The existence of "eka-iodine" had been predicted by Mendeleev. Astatine (after Greek αστατος astatos, meaning "unstable") was first synthesized in 1940 by Dale R. Corson, K. R. MacKenzie, and Emilio Segrè at the University of California, Berkeley by barraging bismuth with alpha particles. An earlier name for the element was alabamine (Ab). Mendeleyevs portrait by Ilya Repin. ... Year 1940 (MCMXL) was a leap year starting on Monday (link will display the full 1940 calendar) of the Gregorian calendar. ... Dale R. Corson (born 1914) is an U.S. educator. ... Portrait of Dr. Emilio Segre Emilio Gino Segrè (February 1, 1905 - April 22, 1989) was an Italian American physicist who, with Owen Chamberlain, won the 1959 Nobel Prize in Physics for their discovery of the antiproton. ... Sather tower (the Campanile) looking out over the San Francisco Bay and Mount Tamalpais. ... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous reddish white Atomic mass 208. ... An alpha particle is deflected by a magnetic field Alpha radiation consists of helium-4 nuclei and is readily stopped by a sheet of paper. ...


Occurrence

Astatine is produced by bombarding bismuth with energetic alpha particles to obtain relatively long-lived 209At - 211At, which can then be distilled from the target by heating in the presence of air. General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous reddish white Atomic mass 208. ... An alpha particle is deflected by a magnetic field Alpha particles or alpha rays are a form of particle radiation which are highly ionizing and have low penetration. ... Laboratory distillation set-up: 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed control 13: Stirrer/heat plate...


Compounds

Multiple compounds of astatine have been synthesized in microscopic amounts and studied as intensively as possible before their inevitable radioactive disintegration. These compounds are primarily of theoretical interest; however, they are also being studied for potential use in nuclear medicine.[citation needed] A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... Shown above is the bone scintigraphy of a young woman. ...


Isotopes

Main article: isotopes of astatine

Astatine has 33 known isotopes, all of which are radioactive; the range of their mass numbers is from 191 to 223. There exist also 23 metastable excited states. The longest-lived isotope is 210At, which has a half-life of 8.3 hours; the shortest-lived known isotope is 213At, which has a half-life of 125 nanoseconds. Astatine (At) Has no stable isotopes. ... For other uses, see Isotope (disambiguation). ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Metastability is the ability of a non-equilibrium state to persist for a long period of time. ... After absorbing energy, an electron may jump from the ground state to a higher energy excited state. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... A nanosecond is an SI derived unit of time equal to 10-9 of a second. ...


References

External links

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  Results from FactBites:
 
It's Elemental - The Element Astatine (0 words)
Astatine is pronounced as AS-teh-teen or as AS-teh-ten.
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.
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.
Chemistry : Periodic Table : astatine : key information (222 words)
Astatine is a halogen and possibly accumulates in the thyroid like iodine.
Astatine is radioactive and essentially unavailable in nature.
The bismuth target is cooled during irradiation to prevent the volatile astatine disappearing.
  More results at FactBites »

 
 

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