Seleniu
34
Se
Grupă
16
Perioadă
4
Bloc
p
Protoni
Electroni
Neutroni
34
34
45
Proprietăți Generale
Număr atomic
34
Masă atomică
78,96
Numar de masa
79
Categorie
Alte nemetale
Culoare
Gri
Radioactive
Nu
Din cuvântul grecesc Selene, lună
Structură cristalină
Simplu Monoclinic
Istoric
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.
Electroni pe nivelul de energie
2, 8, 18, 6
Configurație electronică
[Ar] 3d10 4s2 4p4
Selenium deficiency in animals can lead to slow growth
Proprietăți Fizice
Fază
Solid
Densitate
4,809 g/cm3
Punct de topire
494,15 K | 221 °C | 429,8 °F
Punct de fierbere
958,15 K | 685 °C | 1265 °F
Energie de fuziune
5,4 kJ/mol
Energie de evaporare
26 kJ/mol
Căldură specifică
0,321 J/g·K
Abundența în scoarța Pământului
5×10-6%
Abundența în Univers
3×10-6%
Numarul CAS
7782-49-2
Număr CID PubChem
6326970
Proprietăți Atomice
Rază atomică
120 pm
Rază de covalență
120 pm
Electronegativitate
2,55 (Scara lui Pauling)
Potențial de ionizare
9,7524 eV
Volum molar
16,45 cm3/mol
Conductivitate termică
0,0204 W/cm·K
Număr de oxidare
-2, 2, 4, 6
Aplicații
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
Izotopi
Izotopi stabili
74Se, 76Se, 77Se, 78Se, 80SeIzotopi instabili
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