Template:Infobox selenium

Selenium, 34Se
Selenium
Pronunciation/sɪˈlniəm/ (sə-LEE-nee-əm)
Appearancegrey metallic-looking, red, and vitreous black (not pictured) allotropes
Standard atomic weight Ar°(Se)
78.971(8)[1]
Selenium in the periodic table
HydrogenHelium
LithiumBerylliumBoronCarbonNitrogenOxygenFluorineNeon
SodiumMagnesiumAluminiumSiliconPhosphorusSulfurChlorineArgon
PotassiumCalciumScandiumTitaniumVanadiumChromiumManganeseIronCobaltNickelCopperZincGalliumGermaniumArsenicSeleniumBromineKrypton
RubidiumStrontiumYttriumZirconiumNiobiumMolybdenumTechnetiumRutheniumRhodiumPalladiumSilverCadmiumIndiumTinAntimonyTelluriumIodineXenon
CaesiumBariumLanthanumCeriumPraseodymiumNeodymiumPromethiumSamariumEuropiumGadoliniumTerbiumDysprosiumHolmiumErbiumThuliumYtterbiumLutetiumHafniumTantalumTungstenRheniumOsmiumIridiumPlatinumGoldMercury (element)ThalliumLeadBismuthPoloniumAstatineRadon
FranciumRadiumActiniumThoriumProtactiniumUraniumNeptuniumPlutoniumAmericiumCuriumBerkeliumCaliforniumEinsteiniumFermiumMendeleviumNobeliumLawrenciumRutherfordiumDubniumSeaborgiumBohriumHassiumMeitneriumDarmstadtiumRoentgeniumCoperniciumNihoniumFleroviumMoscoviumLivermoriumTennessineOganesson
S

Se

Te
arsenicseleniumbromine
Atomic number (Z)34
Groupgroup 16 (chalcogens)
Periodperiod 4
Block  p-block
Electron configuration[Ar] 3d10 4s2 4p4
Electrons per shell2, 8, 18, 6
Physical properties
Phase at STPsolid
Melting point494 K ​(221 °C, ​430 °F)
Boiling point958 K ​(685 °C, ​1265 °F)
Density (near r.t.)gray: 4.81 g/cm3
alpha: 4.39 g/cm3
vitreous: 4.28 g/cm3
when liquid (at m.p.)3.99 g/cm3
Critical point1766 K, 27.2 MPa
Heat of fusiongray: 6.69 kJ/mol
Heat of vaporization95.48 kJ/mol
Molar heat capacity25.363 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)500552617704813958
Atomic properties
Oxidation states−2, −1, 0,[2] +1,[3] +2, +3, +4, +5, +6 (a strongly acidic oxide)
ElectronegativityPauling scale: 2.55
Ionization energies
  • 1st: 941.0 kJ/mol
  • 2nd: 2045 kJ/mol
  • 3rd: 2973.7 kJ/mol
Atomic radiusempirical: 120 pm
Covalent radius120±4 pm
Van der Waals radius190 pm
Color lines in a spectral range
Spectral lines of selenium
Other properties
Natural occurrenceprimordial
Crystal structure ​trigonal
Trigonal crystal structure for selenium
Speed of sound thin rod3350 m/s (at 20 °C)
Thermal expansionamorphous: 37 µm/(m⋅K) (at 25 °C)
Thermal conductivityamorphous: 0.519 W/(m⋅K)
Magnetic orderingdiamagnetic[4]
Molar magnetic susceptibility−25.0×10−6 cm3/mol (298 K)[5]
Young's modulus10 GPa
Shear modulus3.7 GPa
Bulk modulus8.3 GPa
Poisson ratio0.33
Mohs hardness2.0
Brinell hardness736 MPa
CAS Number7782-49-2
History
Namingafter Selene, Greek goddess of the moon
Discovery and first isolationJöns Jakob Berzelius and Johann Gottlieb Gahn (1817)
Isotopes of selenium
Main isotopes[6]Decay
abun­dancehalf-life (t1/2)modepro­duct
72Sesynth8.4 dε72As
γ
74Se0.860%stable
75Sesynth119.8 dε75As
γ
76Se9.23%stable
77Se7.60%stable
78Se23.7%stable
79Setrace3.27×105 yβ79Br
80Se49.8%stable
82Se8.82%1.08×1020 yββ82Kr
 Category: Selenium
| references
Data sets read by {{Infobox element}}
Name and identifiers
Symbol etymology (11 non-trivial)
Top image (caption, alt)
Pronunciation
Allotropes (overview)
Group (overview)
Period (overview)
Block (overview)
Natural occurrence
Phase at STP
Oxidation states
Spectral lines image
Electron configuration (cmt, ref)
Isotopes
Standard atomic weight
  most stable isotope
Wikidata
Wikidata *
* Not used in {{Infobox element}} (2023-01-01)
See also {{Index of data sets}} · Cat:data sets (11) · (this table: )

References