Selen

34
Se
Skupina
16
Perioda
4
Blok
p
Protons
Electrons
Neutrons
34
34
45
General Properties
Vrstno število
34
Atomska teža
78,96
Mass Number
79
Kategorija
Druge nekovine
Barva
Gray
Radioactive
Ne
From the Greek word Selene, moon
Kristalna struktura
Primitivna monolinska
Zgodovina
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.
Electrons per shell
2, 8, 18, 6
Razporeditev elektronov
[Ar] 3d10 4s2 4p4
Se
Selenium deficiency in animals can lead to slow growth
Physical Properties
Faza snovi
Trdnina
Gostota
4,809 g/cm3
Tališče
494,15 K | 221 °C | 429,8 °F
Vrelišče
958,15 K | 685 °C | 1265 °F
Talilna toplota
5,4 kJ/mol
Izparilna toplota
26 kJ/mol
Toplotna kapaciteta
0,321 J/g·K
Abundance in Earth's crust
5×10-6%
Abundance in Universe
3×10-6%
Ultrapure
Zasluge za slike: Images-of-elements
Ultrapure black, amorphous selenium
CAS Number
7782-49-2
PubChem CID Number
6326970
Atomic Properties
Atomski polmer
120 pm
Kovalentni polmer
120 pm
Elektronegativnost
2,55 (Paulingova lestvica)
Ionization Potential
9,7524 eV
Atomic Volume
16,45 cm3/mol
Toplotna prevodnost
0,0204 W/cm·K
Oksidacijska stanja
-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
Isotopes
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