Template:Infobox selenium

{{Infobox element

|symbol =Se

|Z =34

|number =34

|name =selenium

|abundance=

|abundance in earth's crust=

|abundance in oceans=

|abundance in solar system=

|left=arsenic

|right=bromine

|above=S

|below=Te

|image name=SeBlackRed.jpg

|appearance=grey metallic-looking, red, and vitreous black (not pictured) allotropes

|electrons per shell=2, 8, 18, 6

|phase=

|density gpcm3nrt=gray: 4.81

|density gpcm3nrt 2=alpha: 4.39

|density gpcm3nrt 3=vitreous: 4.28

|density gpcm3mp=3.99

|melting point K=494

|melting point C=220.85

|melting point F=429.53

|boiling point K=958

|boiling point C=685

|boiling point F=1265

|critical point K=1766

|critical point MPa=27.2

|heat fusion=gray: 6.69

|heat vaporization=95.48

|heat capacity=25.363

|vapor pressure 1=500

|vapor pressure 10=552

|vapor pressure 100=617

|vapor pressure 1 k=704

|vapor pressure 10 k=813

|vapor pressure 100 k=958

|vapor pressure comment=

|crystal structure=hexagonal

|crystal structure prefix=grey:

|crystal structure Pearson symbol=hP3

|lattice constants=a = 436.46 pm
c = 495.77 pm (at 20 °C){{cite book |last=Arblaster |first= John W. |title=Selected Values of the Crystallographic Properties of Elements |publisher=ASM International |publication-place=Materials Park, Ohio |date=2018 |isbn=978-1-62708-155-9}}

|electronegativity=2.55

|number of ionization energies=3

|ionization energy 1=941.0

|ionization energy 2=2045

|ionization energy 3=2973.7

|atomic radius=120

|covalent radius=120±4

|Van der Waals radius=190

|magnetic ordering=diamagnetic

|magnetic ordering ref=[http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/elementmagn.pdf Magnetic susceptibility of the elements and inorganic compounds], in {{RubberBible86th}}

|thermal conductivity=amorphous: 0.519

|thermal expansion at 25=amorphous: 37

|speed of sound rod at 20=3350

|magnetic susceptibility= {{val|−25.0|e=−6}}

|magnetic susceptibility ref= (298 K){{Cite book|title=CRC, Handbook of Chemistry and Physics|last=Weast|first=Robert|publisher=Chemical Rubber Company Publishing|year=1984|isbn=0-8493-0464-4|location=Boca Raton, Florida|pages=E110}}

|Young's modulus=10

|Shear modulus=3.7

|Bulk modulus=8.3

|Poisson ratio=0.33

|Mohs hardness=2.0

|Brinell hardness=736

|CAS number=7782-49-2

|naming=after Selene, Greek goddess of the moon

|discovery and first isolation by=Jöns Jakob Berzelius and Johann Gottlieb Gahn

|discovery date=1817

|QID=Q876

}}