Osmium vs Iridium

Side-by-side comparison of Osmium (Os, element 76) and Iridium (Ir, element 77) by atomic structure and physical properties.

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PropertyOs Osmium Ir Iridium
Atomic number7677
SymbolOsIr
NameOsmiumIridium
Categorytransition-metaltransition-metal
Standard Atomic Weight190.23 u192.217 u
Period66
Group89
Blockdd
Phase at STPSolidSolid
Electron configuration[Xe]4f145d66s2[Xe]4f145d76s2
Oxidation states[-4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8][-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Electronegativity (Pauling)2.22.2
Electron affinity1.077661 eV1.565 eV
Density2.25872e+4 kg/m³2.25622e+4 kg/m³
Melting point3032.85 °C2445.85 °C
Boiling point5011.85 °C4427.85 °C
Discovery year18031803

Key Differences

PropertyOs OsmiumIr Iridium
Standard Atomic Weight190.23 u ↓ lower192.217 u ↑ higher
Density2.25872e+4 kg/m³ ↑ higher2.25622e+4 kg/m³ ↓ lower
Melting point3032.85 °C ↑ higher2445.85 °C ↓ lower
Boiling point5011.85 °C ↑ higher4427.85 °C ↓ lower
Electron affinity1.077661 eV ↓ lower1.565 eV ↑ higher
Group8 9
Electron configuration[Xe]4f145d66s2 [Xe]4f145d76s2