Symbol
Se
Atomic Number
34
Atomic Mass
78.971
Protons
34
Neutrons
44
Electrons
34
Type
Nonmetal
Isotopes
Selenium-74, Selenium-76, Selenium-77, Selenium-78, Selenium-80, Selenium-82
Discovery Year
1817
Discovered By
Johan Gottlieb Gahn
Group
16
Period
4
Boiling Point
685°F
Melting Point
217°F
Electron Configuration
[Ar] 3d¹⁰ 4s² 4p⁴
Density (g/cm³)
4.809
Crystal Structure
Hexagonal
Magnetism
Diamagnetic
Abundance in Earth's Crust
0.019%
Phase at Room Temperature
Solid