Home 34 Se Selenium back to the periodic table

Atomic number   34
Symbol   Se
Atomic weight   78.96
Density [g/cm3]   4.82
Melting point [°C]   217
Boiling point [°C]   685
1st Ionization energy [eV]   9.752
Electronic configuration   [Ar] 3d10 4s2 4p4
Oxidation number (most stable)   6, 4, 2
Atomic radius [pm]   116
Ionic radius [pm]   198 (2-)
Abundance in crustal rocks [ppm]   0.05
Origin of the name   (greek) selene = moon, due to its relationship with tellurium (=earth)
Discovery   1817 by the Swede Berzelius
Uses   for semi-conductors and photocells, and due to ist photo-electric characteristics in picture drums in photocopying machines.

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© 2004 Büro für angewandte Mineralogie · Dr. Stephan Rudolph · D-47918 Tönisvorst
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