Selen

34
Se
Gruppe
16
Periode
4
Block
p
Protonen
Elektronen
Neutronen
34
34
45
Generelle Eigenschaften
Ordnungszahl
34
Atommasse
78,96
Massenzahl
79
Kategorie
Nichtmetalle
Farbe
Grau
Radioaktiv
Nein
Aus dem Griechischen Selene (Mond)
Kristallstruktur
Einfach monoklin
Geschichte
Selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova.

Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn who noted the similarity of the new element to the previously-known tellurium.

In 1873, Willoughby Smith found that the electrical resistance of grey selenium was dependent on the ambient light.
Elektronen pro Schale
2, 8, 18, 6
Elektronenkonfiguration
[Ar] 3d10 4s2 4p4
Se
Selenium deficiency in animals can lead to slow growth
Physikalische Eigenschaften
Aggregatzustand
Fest
Dichte
4,809 g/cm3
Schmelzpunkt
494,15 K | 221 °C | 429,8 °F
Siedepunkt
958,15 K | 685 °C | 1265 °F
Schmelzwärme
5,4 kJ/mol
Verdampfungswärme
26 kJ/mol
Spezifische Wärmekapazität
0,321 J/g·K
Häufigkeit in der Erdkruste
5×10-6%
Häufigkeit im Universum
3×10-6%
Ultrapure
Danksagungen für Bilder: Images-of-elements
Ultrapure black, amorphous selenium
CAS-Nummer
7782-49-2
PubChem CID Number
6326970
Atomeigenschaften
Atomradius
120 pm
Kovalenter Radius
120 pm
Elektronegativität
2,55 (Pauling-Skala)
Ionisierungsenergie
9,7524 eV
Molares Volumen
16,45 cm3/mol
Wärmeleitfähigkeit
0,0204 W/cm·K
Oxidationszustände
-2, 2, 4, 6
Anwendung
Selenium is used in the glass industry to decolorize glass and to make red-colored glasses and enamels.

It is used as a catalyst in many chemical reactions.

It is also used as a photographic toner, and as an additive to stainless steel.

Selenium sulfide is used in anti-dandruff shampoos.
Many of selenium's compounds, such as selenates and selenites, are highly toxic
Isotope
Stabile Isotope
74Se, 76Se, 77Se, 78Se, 80Se
Instabile Isotope
65Se, 66Se, 67Se, 68Se, 69Se, 70Se, 71Se, 72Se, 73Se, 75Se, 79Se, 81Se, 82Se, 83Se, 84Se, 85Se, 86Se, 87Se, 88Se, 89Se, 90Se, 91Se, 92Se, 93Se, 94Se