Solid phase
Official name
amorphous Selenium
Secondary names
amorphous Se
CAS number
7782-49-2
Type
Family
metallic solid
Class
pseudometal (semi-conductor)
Compound type
elemental solid
Chemical composition
Formula
$Se$
Chemical formula
Se
Elemental formula
Se8
Isotope mixture type
terrestrial abundance
16.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$Se$ Selenium element 8 1.0 1 constituent element main
Composition comments
puckered $Se_8$ rings
Chemical bonds
  Bond Number
$-Se-Se-$ 2
Class
pseudometals (14)
Type
homovalent monolayer pseudometals (14.01)
Phase name
amorphous Se
Phase type
amorphous
Crystal system
amorphous
Crystal class
N/A
Crystal class symbol
N/A
Crystal spacegroup
N/A
Molar mass
78.971 $g/mol$
Density
4.3 $g/cm^3$
State NTP
solid
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid to gray Selenium > 180°C (> 453 K)
Phase transitions comments
When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. When rapidly melted, it forms the black, vitreous form.
Refringence type
isotropic
Pure color
red
Color
brick-red, reddish
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