Se - Selenium

Selenium

Selenium

Atomic Number:	34
Atomic Weight:	78.96
Element Type:	Non-Metal
Crystal Structure:	Hexagonal
Melting Point:	221.0°C = 429.8°F = 494.15 K
Boiling Point:	685.0°C = 1265.0°F = 958.15 K
Critical Temp:	1493.0°C = 2719.4°F = 1766.15 K
Atomic Radius:	1.22 Å (Å = Angstrom = 10^-10 m)
Covalent Radius:	1.16 Å
Electronegativity:	2.55

History

(Gr. Selene, moon) Discovered by Berzelius in 1817, who found it associated withtellurium, named for the earth.

Sources

'You cannot hope to build a better world without improving the individuals. To that end each of us must work for his own improvement, and at the same time share a general responsibility for all humanity, our particular duty being to aid those to whom we think we can be most useful.'

Marie Curie
(1867-1934)