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Selenium

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ArsenicoSeleniumBromo
Apparentia
allotropos nigre e rubie
Proprietates atomic
Nomine, symbolo, numero Selenium, Se, 34
Serie chimic nonmetallo
Gruppo, periodo, bloco 16, 4, p
Configuration electronic [Ar] 4s2 3d10 4p4
Electronegativitate 2,55
Proprietates physic
Stato solido
Massa molar 78,96 g·mol-1
Densitate (gris) 4,81, (alpha) 4,39, (vitrose) 4,28 g/cm3
Densitate liquide al p.f. 3,99 g·cm−3
Puncto de fusion 494 K, 221 °C, 430 °F
Puncto de ebullition 958 K, 685 °C, 1265 °F
Puncto critic 1766 K, 27,2 MPa
Calor de fusion (gris) 6,69 kJ·mol-1
Calor de vaporisation 95,48 kJ·mol-1
Calor specific 25,363 J·mol-1·K-1
Conductivitate thermal (amorphe) 0,519 W·m-1·K-1
Expansion thermal (25 °C) (amorphe) 37 µm·m−1·K−1
Velocitate de sono (20 °C) 3350 m·s−1
Valores in unitates SI e in le conditiones normal del material (25 °C, 100 kPa) si non indica al contrario.

Selenium es un elemento chimic con le symbolo Se e numero atomic 34. Illo es un nonmetallo con proprietates que son intermedie inter illos de su vecinos columnal chalcogenic in le tabella periodic, le elementos sulfure e tellurium. Illo rarmente occurre in su stato elemental in natura, o como compositos mineral pur. Selenium (greco: σελήνη, selene, significante "Luna") era discoperite in 1817 per Jöns Jacob Berzelius, qui notava le similaritate del nove elemento al previose cognoscite tellurium (appellate pro le Terra).

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