Selenium

34
Se
Gruppe
16
Periode
4
Blok
p
Protons
Electrons
Neutrons
34
34
45
General Properties
Atomnummer
34
Atommasse
78,96
Mass Number
79
Kategori
Andre ikke-metaller
Farve
Grå
Radioactive
Nej
From the Greek word Selene, moon
Krystalstruktur
Simpel Monoklin
History
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.
Elektroner i hver skal
2, 8, 18, 6
Elektronkonfiguration
[Ar] 3d10 4s2 4p4
Se
Selenium deficiency in animals can lead to slow growth
Physical Properties
Tilstandsform
Fast stof
Massefylde
4,809 g/cm3
Smeltepunkt
494,15 K | 221 °C | 429,8 °F
Kogepunkt
958,15 K | 685 °C | 1265 °F
Smeltevarme
5,4 kJ/mol
Fordampningsvarme
26 kJ/mol
Varmefylde
0,321 J/g·K
Abundance in Earth's crust
5×10-6%
Abundance in Universe
3×10-6%
Ultrapure
Billede akkrediteringer: Images-of-elements
Ultrapure black, amorphous selenium
CAS Number
7782-49-2
PubChem CID Number
6326970
Atomic Properties
Atomradius
120 pm
Kovalent radius
120 pm
Elektronegativitet
2,55 (Paulings skala)
Ionization Potential
9,7524 eV
Atomic Volume
16,45 cm3/mol
Varmeledningsevne
0,0204 W/cm·K
Oxidationstrin
-2, 2, 4, 6
Applications
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
Isotoper
Stable Isotopes
74Se, 76Se, 77Se, 78Se, 80Se
Unstable Isotopes
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