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Element 55 - Cesium (Cs) sound

From caesius, or sky-blue (its salts turn flames blue); discovered 1860; the softest metal, liquid at warm room temperature. Extremely reactive, it finds limited use in vacuum tubes and in atomic clocks so accurate that they vary no more than five seconds in 10 generatirons.

Properties

Atomic Number: 55
Atomic Weight: 132.9054
Electron Configuration (at ground state): 1s22s22p63s23p63d104s24p64d105s25p66s1
Oxidation States (Bold most stable): +1
Boiling Point (K): 944
Melting Point (K): 301.54
Density (at 300K -- g/cm3): 1.87
Atomic Volume (at 300K -- cm3/mol) 70
Number of stable isotopes: 1
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 134 -- 2.06 years -- beta particle (electron) emission
135 -- 2.9 x 106 years -- beta particle (electron) emission
137 -- 30.17 years -- beta particle (electron) emission
Covalent Radius (Å): 2.35
Atomic Radius (Å): 2.67
First Ionization Potential (V): 3.894
Electronegativity (Pauling's): 0.79
Specific Heat Capacity (at 300K -- J g-1 K-1): 0.24
Heat of Vaporization (kJ/mol): 67.740
Heat of Fusion (kJ/mol): 2.092
Electrical Conductivity (at 293K for polycrystalline material -- 106 (ohms)-1 cm-1): 5.3
Thermal Conductivity (at 300K -- W m-1 K-1): 35.9
Crystal Structure: Cubic, body centered
Acid-Base Properties: Very basic