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Element 34 - Selenium (Se) sound

From selene, or moon; discovered 1817; unlike most electrical conductors, selenium varies in conductivity with variations in light. This "photoelectric" trait suits it for service in electric eyes, solar cells, television cameras, and light meters.

Properties

Atomic Number: 34
Atomic Weight: 78.96
Electron Configuration (at ground state): 1s22s22p63s23p63d104s24p4
Oxidation States (Bold most stable): -2, +4, +6
Boiling Point (K): 958
Melting Point (K): 494
Density (at 300K -- g/cm3): 4.79
Atomic Volume (at 300K -- cm3/mol) 16.50
Number of stable isotopes: 6
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 75 -- 118.5 days -- beta particle (electron) emission
79 -- 6.5 x 104 years -- beta particle (electron) emission
Covalent Radius (Å): 1.16
Atomic Radius (Å): 1.40
First Ionization Potential (V): 9.752
Electronegativity (Pauling's): 2.55
Specific Heat Capacity (at 300K -- J g-1 K-1): 0.32
Heat of Vaporization (kJ/mol): 26.32
Heat of Fusion (kJ/mol): 5.54
Electrical Conductivity (at 293K for polycrystalline material -- 106 (ohms)-1 cm-1): 8
Thermal Conductivity (at 300K -- W m-1 K-1): 2.04
Crystal Structure: Hexagonal
Acid-Base Properties: Very acidic