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Element 77 - Iridium (Ir) sound

From iris, or rainbow, so named for its colorful salts; discovered 1804. Very hard and hence extremely difficult to work or cast, iridium hardens other metals. Its alloys make bars used as standard weights and measures. The international "standard meter" is platinum-iridium

Properties

Atomic Number: 77
Atomic Weight: 192.22
Electron Configuration (at ground state): 1s22s22p63s23p63d104s24p64d104f145s25p65d76s2
Oxidation States (Bold most stable): +2, +3, +4, +6
Boiling Point (K): 4700
Melting Point (K): 2720
Density (at 300K -- g/cm3): 22.6
Atomic Volume (at 300K -- cm3/mol) 8.54
Number of stable isotopes: 2
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 192 -- 74.2 days -- beta particle (electron) emission
, positron emission, orbital electron capture
Covalent Radius (Å): 1.27
Atomic Radius (Å): 1.36
First Ionization Potential (V): 9.1
Electronegativity (Pauling's): 2.20
Specific Heat Capacity (at 300K -- J g-1 K-1): 0.130
Heat of Vaporization (kJ/mol): 563.58
Heat of Fusion (kJ/mol): 26.36
Electrical Conductivity (at 293K for polycrystalline material -- 106 (ohms)-1 cm-1): 21.3
Thermal Conductivity (at 300K -- W m-1 K-1): 147
Crystal Structure: Cubic, face centered
Acid-Base Properties: Very basic