Selenium

Reactive nonmetals · Group 16 · Period 4

Atomic properties

Atomic number	34
Symbol	Se
Standard atomic weight	78.971
Classification	Reactive nonmetals
Group	16
Period	4
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p4
Electronegativity (Pauling)	2.55
Common oxidation states	+6, +4, -2

Physical properties

Phase at 20 °C	Solid
Density	4.81 g/cm³
Melting point	221 °C
Boiling point	685 °C
Discovered	1817
CAS number	—

Need a material? Ask us for a written proposition.

Any metal, powder, wire, oxide or purity. Stock is held in high-security bonded storage at Zurich Airport — no import duties or VAT while goods stay in bond, any quantity, in-house air, sea, land and express logistics. Written trade inquiries only.