Periodic table of the elements
ArsenicSeleniumBromine
34
Se
Selenium
78.96		2
8
18
6
34
Se
Selenium
78.96		2
8
18
6
General
NameSelenium
SymbolSe
Number34
Chemical seriesOther nonmetals
Group / Period16 / 4
Blockp-block
CAS registry number7782-49-2

Physical properties
Statesolid
Density4.79 g/cm3
Melting point494 K (221 °C, 430 °F)
Boiling point958 K (685°C, 1265°F)
Critical point1766 K, 27.2 MPa

Atomic properties
Atomic Weight78.96 g/mol
Crystal structurehexagonal
Electronegativity2.55
Atomic radius115 pm
Atomic radius (calculated)103 pm
Electron configuration[Ar] 4s2 3d10 4p4
Electrons per shell2, 8, 18, 6
Number of protons34
Number of neutrons45

Other languages
SpanishSelenio
PortugueseSelénio
FrenchSélénium
GermanSelen
ItalianSelenio
RussianСелен
PolishSelen
Chinese硒
Arabicسيلينيوم
TurkishSelenyum
DutchSeleen


Periodic table of the elements
ArsenicSeleniumBromine