Astat

85
At
Gruppe
17
Periode
6
Block
p
Protonen
Elektronen
Neutronen
85
85
125
Generelle Eigenschaften
Ordnungszahl
85
Atommasse
[210]
Massenzahl
210
Kategorie
Halogene
Farbe
Silber
Radioaktiv
Ja
From the Greek astatos meaning unstable
Kristallstruktur
n/a
Geschichte
In 1869, existence of astatine was first predicted by Russian chemist Dmitri Mendeleev and called the element eka-iodine.

In 1940, Dale R. Corson, Kenneth Ross MacKenzie, and Emilio Segrè isolated the element at the University of California, Berkeley.

Instead of searching for the element in nature, the scientists created it by bombarding bismuth-209 with alpha particles.
Elektronen pro Schale
2, 8, 18, 32, 18, 7
Elektronenkonfiguration
[Xe] 4f14 5d10 6s2 6p5
At
Astatine is preferentially concentrated in the thyroid gland
Physikalische Eigenschaften
Aggregatzustand
Fest
Dichte
7 g/cm3
Schmelzpunkt
575,15 K | 302 °C | 575,6 °F
Siedepunkt
610,15 K | 337 °C | 638,6 °F
Schmelzwärme
6 kJ/mol
Verdampfungswärme
40 kJ/mol
Spezifische Wärmekapazität
-
Häufigkeit in der Erdkruste
n/a
Häufigkeit im Universum
n/a
Emilio
Danksagungen für Bilder: pauli.uni-muenster.de
Emilio Segrè, one of the discoverer of the element
CAS-Nummer
7440-68-8
PubChem CID Number
n/a
Atomeigenschaften
Atomradius
-
Kovalenter Radius
150 pm
Elektronegativität
2,2 (Pauling-Skala)
Ionisierungsenergie
9,3 eV
Molares Volumen
30 cm3/mol
Wärmeleitfähigkeit
0,017 W/cm·K
Oxidationszustände
-1, 1, 3, 5, 7
Anwendung
The newly formed astatine-211 is important in nuclear medicine.

Once produced, astatine must be used quickly, as it decays with a half-life of 7.2 hours.

Astatine-211 can be used for targeted alpha particle radiotherapy, since it decays either via emission of an alpha particle.
Astatine is highly radioactive
Isotope
Stabile Isotope
-
Instabile Isotope
193At, 194At, 195At, 196At, 197At, 198At, 199At, 200At, 201At, 202At, 203At, 204At, 205At, 206At, 207At, 208At, 209At, 210At, 211At, 212At, 213At, 214At, 215At, 216At, 217At, 218At, 219At, 220At, 221At, 222At, 223At