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