Basic Information
Name:selenium
Symbol:se
Classification:Selenium is a chalcogen and a nonmetal
color: gray or red (crystalline), black or
red (amorphous)
Atomic weight :78.96
state: solid
Melting Point: 220 oC, 493 K
Boiling Point:685 oC, 958 K
Shells:2,8,18,6
Electron configuration:[Ar] 3d10 4s2 4p4
Density @ 20oC:4.79 g/cm3
Atomic volume:16.45 cm3/mol
Structure: long, helical chains (crystalline hexagonal), Se8
rings (crystalline monoclinic)
2.50mohs