Selen
34
Se
Skupina
16
Perioda
4
Blok
p
Protony
Elektrony
Neutrony
34
34
45
Hlavní vlastnosti
Atomové číslo
34
Atomová hmotnost
78,96
Hmotnostní číslo
79
Kategorie
Ostatní nekovy
Barva
Šedá
Radioaktivní
Ne
From the Greek word Selene, moon
Krystalografická soustava
Monoklinická
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.
Elektronů v obalu
2, 8, 18, 6
Elektronová konfigurace
[Ar] 3d10 4s2 4p4
Selenium deficiency in animals can lead to slow growth
Fyzické vlastnosti
Skupenství
Pevná
Hustota
4,809 g/cm3
Teplota tání
494,15 K | 221 °C | 429,8 °F
Teplota varu
958,15 K | 685 °C | 1265 °F
Skupenské teplo tání
5,4 kJ/mol
Skupenské teplo varu
26 kJ/mol
Měrná tepelná kapacita
0,321 J/g·K
Hojnost v zemské kůře
5×10-6%
Hojnost ve vesmíru
3×10-6%
Číslo CAS
7782-49-2
PubChem CID číslo
6326970
Atomové vlastnosti
Atomový poloměr
120 pm
Kovalentní poloměr
120 pm
Elektronegativita
2,55 (Paulingova stupnice)
Ionizační potenciál
9,7524 eV
Molární objem
16,45 cm3/mol
Tepelná vodivost
0,0204 W/cm·K
Oxidační čísla
-2, 2, 4, 6
Aplikace
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.
Mnoho sloučenin selenu, jako selenáty a selenity, jsou vysoce toxické
Izotopy
Stabilní izotopy
74Se, 76Se, 77Se, 78Se, 80SeNestabilní izotopy
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