Astatine, 85 General properties Pronunciation Template:Infobox element/pronunciation Appearance unknown, probably metallic Standard atomic weight (A r, standard ) Template:Infobox element/standard atomic weight Mass number Template:Infobox element/symbol-to-most-stable-isotope (most stable isotope)Astatine in the periodic table Template:Infobox element/periodic table Atomic number (Z ) 85 Group Template:Infobox element/group Period period 6 Block p-block Element category Template:Infobox element/category format , sometimes classified as a nonmetal, or a metal Template:Sfn [1] Electron configuration [Xe ] 4f14 5d10 6s2 6p5 Electrons per shell
2, 8, 18, 32, 18, 7 Physical properties Phase at STP solid Melting point 575 K (302 °C, 576 °F) Boiling point 610 K (337 °C, 639 °F) Density (near r.t. ) (At2 ) 6.35±0.15 g/cm3 (predicted) [2] Molar volume (At2 ) 32.94 cm3 /mol (predicted) [2] [[Enthalpy of vaporization|Heat of Template:Engvar ]] (At2 ) 54.39 kJ/mol[3] [[Vapor pressure|Template:Engvar pressure Atomic properties Oxidation states Template:Infobox element/symbol-to-oxidation-state Electronegativity Pauling scale: 2.2 [[Ionization energy|Template:Engvar energies]] Covalent radius 150 pm Van der Waals radius 202 pm Template:Infobox element/spectral lines Other properties Crystal structure Template:Infobox element/crystal structure (predicted) [1] Thermal conductivity 1.7 W/(m·K) CAS Number 7440-68-8 History Naming after Greek astatos (αστατος), meaning "unstable" Discovery Dale R. Corson , Kenneth Ross MacKenzie , Emilio Segrè (1940) Main isotopes of astatine Template:Infobox element/isotopes table | references
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↑ 1.0 1.1 Hermann, A.; Hoffmann, R.; Ashcroft, N. W. (2013). "Condensed Astatine: Monatomic and Metallic". Physical Review Letters . 111 (11): 116404–1–116404–5. Bibcode :2013PhRvL.111k6404H . doi :10.1103/PhysRevLett.111.116404 . PMID 24074111 . ↑ 2.0 2.1 Bonchev, D.; Kamenska, V. (1981). "Predicting the Properties of the 113–120 Transactinide Elements" . The Journal of Physical Chemistry . ACS Publications. 85 (9): 1177–86. doi :10.1021/j150609a021 . Retrieved 6 May 2013 . ↑ Glushko, V. P.; Medvedev, V. A.; Bergma, G. A. (1966). Termicheskie Konstanty Veshchestv (in Russian). 1 . Nakua. p. 65. CS1 maint: Unrecognized language (link ) ↑ Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; et al. (2013). "Measurement of the First Ionization Potential of Astatine by Laser Ionization Spectroscopy" . Nature Communications . 4 : 1–6. Bibcode :2013NatCo...4E1835R . doi :10.1038/ncomms2819 . PMC 3674244 PMID 23673620 .