Selen
34
Se
Gruppe
16
Periode
4
Blokk
p
Protoner
Elektroner
Nøytroner
34
34
45
Generelle egenskaper
Atomnummer
34
Atomvekt
78,96
Massetall
79
Kategori
Ikke-metaller
Farge
Grå
Radioaktiv
Nei
From the Greek word Selene, moon
Krystallstruktur
Simple Monoclinic
Historie
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.
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 per energinivå
2, 8, 18, 6
Elektronkonfigurasjon
[Ar] 3d10 4s2 4p4
Selenium deficiency in animals can lead to slow growth
Fysikalske egenskaper
Fase
Fast stoff
Tetthet
4,809 g/cm3
Smeltepunkt
494,15 K | 221 °C | 429,8 °F
Kokepunkt
958,15 K | 685 °C | 1265 °F
Smeltevarme
5,4 kJ/mol
Fordampningsvarme
26 kJ/mol
Spesifikk varmekapasitet
0,321 J/g·K
Forekomst i jordskorpa
5×10-6%
Forekomst i universet
3×10-6%
CAS Number
7782-49-2
PubChem CID Number
6326970
Atomegenskaper
Atomradius
120 pm
Kovalent radius
120 pm
Elektronegativitet
2,55 (Pauling-skalaen)
Ioniseringsenergi
9,7524 eV
Molart volum
16,45 cm3/mol
Termisk ledningsevne
0,0204 W/cm·K
Oksidasjonstilstander
-2, 2, 4, 6
Bruksområder
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.
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
Stabile isotoper
74Se, 76Se, 77Se, 78Se, 80SeUstabile isotoper
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