Basic Information

Name: Selenium 
Symbol: Se 
Atomic Number: 34 
Atomic Mass: 78.96 amu 
Melting Point: 217.0 °C (490.15 K, 422.6 °F) 
Boiling Point: 684.9 °C (958.05005 K, 1264.8201 °F) 
Number of Protons/Electrons: 34 
Number of Neutrons: 45 
Classification: Non-metal 
Crystal Structure: Hexagonal 
Density @ 293 K: 4.79 g/cm3 
Color: gray
Date of Discovery: 1817 
Discoverer: Jons Berzelius 
Name Origin: From the Greek word Selênê (Moon) 
Uses: photoelectric cells, TV cameras 
Obtained From: refining of lead, copper, nickel