Astatine

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Astatine
85At
I

At

Uus
poloniumastatineradon
Appearance
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)
History
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
Miscellanea
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. (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.