Astatine

  • astatine, 85at
    astatine
    pronunciationn/ (as-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
    poloniumastatineradon
    atomic number (z)85
    groupgroup 17 (halogens)
    periodperiod 6
    blockp-block
    element category  metalloid, sometimes classified as a nonmetal, or a metal[1][2]
    electron configuration[xe] 4f14 5d10 6s2 6p5
    electrons per shell2, 8, 18, 32, 18, 7
    physical properties
    phase at stpsolid
    boiling point(at2) 503±3 k ​(230±3 °c, ​446±5 °f) (estimated)[3]
    density (near r.t.)(at2) 6.35±0.15 g/cm3 (predicted)[4]
    molar volume(at2) 32.94 cm3/mol (predicted)[4]
    heat of vaporization(at2) 54.39 kj/mol[5]
    vapor pressure
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 361 392 429 475 531 607
    atomic properties
    oxidation states−1, +1, +3, +5, +7[6]
    electronegativitypauling scale: 2.2
    ionization energies
    • 1st: 899.003 kj/mol[7]
    covalent radius150 pm
    van der waals radius202 pm
    other properties
    natural occurrencefrom decay
    crystal structureface-centered cubic (fcc)
    face-centered cubic crystal structure for astatine

    (predicted)[2]
    thermal conductivity1.7 w/(m·k)
    cas number7440-68-8
    history
    namingafter greek astatos (αστατος), meaning "unstable"
    discoverydale r. corson, kenneth ross mackenzie, emilio segrè (1940)
    main isotopes of astatine
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    209at syn 5.41 h β+ 209po
    α 205bi
    210at syn 8.1 h β+ 210po
    α 206bi
    211at syn 7.21 h ε 211po
    α 207bi
    category category: astatine
    | references

    astatine is a radioactive chemical element with the symbol at and atomic number 85. it is the rarest naturally occurring element in the earth's crust, occurring only as the decay product of various heavier elements. all of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. a sample of the pure element has never been assembled, because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity.

    the bulk properties of astatine are not known with any certainty. many of them have been estimated based on the element's position on the periodic table as a heavier analog of iodine, and a member of the halogens (the group of elements including fluorine, chlorine, bromine, and iodine). astatine is likely to have a dark or lustrous appearance and may be a semiconductor or possibly a metal; it probably has a higher melting point than that of iodine. chemically, several anionic species of astatine are known and most of its compounds resemble those of iodine. it also shows some metallic behavior, including being able to form a stable monatomic cation in aqueous solution (unlike the lighter halogens).

    the first synthesis of the element was in 1940 by dale r. corson, kenneth ross mackenzie, and emilio g. segrè at the university of california, berkeley, who named it from the greek astatos (ἄστατος), meaning "unstable". 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 can only be produced synthetically, usually by bombarding bismuth-209 with alpha particles.

  • characteristics
  • compounds
  • history
  • isotopes
  • natural occurrence
  • synthesis
  • uses and precautions
  • see also
  • notes
  • references
  • bibliography
  • external links

Astatine, 85At
Astatine
Pronunciationn/ (AS-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
poloniumastatineradon
Atomic number (Z)85
Groupgroup 17 (halogens)
Periodperiod 6
Blockp-block
Element category  Metalloid, sometimes classified as a nonmetal, or a metal[1][2]
Electron configuration[Xe] 4f14 5d10 6s2 6p5
Electrons per shell2, 8, 18, 32, 18, 7
Physical properties
Phase at STPsolid
Boiling point(At2) 503±3 K ​(230±3 °C, ​446±5 °F) (estimated)[3]
Density (near r.t.)(At2) 6.35±0.15 g/cm3 (predicted)[4]
Molar volume(At2) 32.94 cm3/mol (predicted)[4]
Heat of vaporization(At2) 54.39 kJ/mol[5]
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 361 392 429 475 531 607
Atomic properties
Oxidation states−1, +1, +3, +5, +7[6]
ElectronegativityPauling scale: 2.2
Ionization energies
  • 1st: 899.003 kJ/mol[7]
Covalent radius150 pm
Van der Waals radius202 pm
Other properties
Natural occurrencefrom decay
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for astatine

(predicted)[2]
Thermal conductivity1.7 W/(m·K)
CAS Number7440-68-8
History
Namingafter Greek astatos (αστατος), meaning "unstable"
DiscoveryDale R. Corson, Kenneth Ross MacKenzie, Emilio Segrè (1940)
Main isotopes of astatine
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
209At syn 5.41 h β+ 209Po
α 205Bi
210At syn 8.1 h β+ 210Po
α 206Bi
211At syn 7.21 h ε 211Po
α 207Bi
Category Category: Astatine
| references

Astatine is a radioactive chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. A sample of the pure element has never been assembled, because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity.

The bulk properties of astatine are not known with any certainty. Many of them have been estimated based on the element's position on the periodic table as a heavier analog of iodine, and a member of the halogens (the group of elements including fluorine, chlorine, bromine, and iodine). Astatine is likely to have a dark or lustrous appearance and may be a semiconductor or possibly a metal; it probably has a higher melting point than that of iodine. Chemically, several anionic species of astatine are known and most of its compounds resemble those of iodine. It also shows some metallic behavior, including being able to form a stable monatomic cation in aqueous solution (unlike the lighter halogens).

The first synthesis of the element was in 1940 by Dale R. Corson, Kenneth Ross MacKenzie, and Emilio G. Segrè at the University of California, Berkeley, who named it from the Greek astatos (ἄστατος), meaning "unstable". 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 can only be produced synthetically, usually by bombarding bismuth-209 with alpha particles.