Selenium
Symbol
Se
Atomic Number
34
Atomic Weight
78.96
Element Classification
Discovered By
Jons Jacob Berzelius
Discovery Date
1818 (Sweden)
Name Origin
Greek: selene (moon).
Density(g/cc)
4.79
Melting Point
490
Boiling Point(K)
958.1
Appearance
A soft metalloid similar to sulfur
Atomic Radius(pm)
140
Atomic Volume(cc/mol)
16.5
Covalent Radius(pm)
116
Ionic Radius
42 (+6e) 191 (-2e)
Specific Heat
0.321 (Se-Se)
Fusion Heat
5.23
Evaporation Heat(kj/mol)
59.7
Thermal Conductivity(@25°C W/m K)
0.52
Debye Temperature
n/a
Pauling Negativity Number
2.55
First Ionizing Energy(kj/mol)
940.4
Oxidation States
6, 4, -2
Electronic Configuration
[Ar] 3d10 4s2 4p4
Lattice Structure
Hexagonal(HEX)
Lattice Constant
4.360
Lattice C/A Ratio
n/a
