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unkent, but probably metallic
General properties
Name, seembol, nummer astatine, At, 85
Pronunciation /ˈæstətn/ AS-tə-teen
or /ˈæstətɪn/ AS-tə-tin
Element category metalloid
(disputit; sometimes classified as a halogen, mey be a metal)[1]
Group, period, block 17 (halogens), 6, p
Staundart atomic wicht (210)
Electron confeeguration [Xe] 4f14 5d10 6s2 6p5
2, 8, 18, 32, 18, 7
Electron shells of astatine (2, 8, 18, 32, 18, 7)
Discovery Dale R. Corson, Kenneth Ross MacKenzie, Emilio Segrè (1940)
Physical properties
Phase solid
Density (near r.t.) (At2) 6.2–6.5 (predictit)[2] g·cm−3
Meltin pynt 575 K, 302 °C, 576 °F
Boilin pynt 610 K, 337 °C, 639 °F
Heat o vaporization (At2) 54.39 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
Oxidation states −1, +1, +3, +5, +7
Electronegativity 2.2 (Pauling scale)
Ionization energies 1st: 899.003[3] kJ·mol−1
Covalent radius 150 pm
Van der Waals radius 202 pm
Thermal conductivity 1.7 W·m−1·K−1
CAS registry nummer 7440-68-8
Most stable isotopes
Main article: Isotopes o astatine
iso NA hauf-life DM DE (MeV) DP
209At syn 5.41 h β+ 3.486 209Po
α 5.758 205Bi
210At syn 8.1 h β+ 3.981 210Po
α 5.632 206Bi
211At syn 7.21 h ε 0.786 211Po
α 5.983 207Bi
· r

Astatine is a radioactive chemical element wi the chemical seembol At an atomic nummer 85. It occurs on Yird anly as the result o the radioactive decay o certain hivier elements. Aw o its isotopes are short-lived; the maist stable is astatine-210, wi a hauf-life o 8.5 oors.[4] Accordinly, much less is kent aboot astatine nor maist ither elements. The observed properties are consistent wi it bein a hivier analog o iodine; mony ither properties hae been estimatit based on this resemblance.

=References[eedit | eedit soorce]

  1. Hermann, Andreas; Hoffmann, Roald; Ashcroft, N. W. (2013). "Condensed Astatine: Monatomic and Metallic". Physical Review Letters 111 (11). doi:10.1103/PhysRevLett.111.116404. 
  2. Bonchev, Danail; Kamenska, Verginia (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. 
  3. 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: 1835–. doi:10.1038/ncomms2819. PMC 3674244. PMID 23673620. 
  4. Price, Andy (2004-12-20). "Francium". Retrieved 2012-02-19.