• Class: Transition Metals
• Period: 6
• IUPAC group: 9
• Traditional: VIII

• Discovered in: 1803 by Tennant
• Origin of name: LaTin: iris, (rainbow)
• Historical or alternate name:

PlaTinum & Nickel ores

Lustrous, Silvery, hard metal. Unreactive in air, water and acids. Attacked by fused NaOH.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.0032 ppm
• Sea water: ~0.0 ppm
• Metallic meteorite: 0.473 ppm
• ConTinental crust: 0.0001 ppm
• Solar photosphere: 0.85 log of abundance
• Oceanic crust: 2.0E-6 ppm
• Solar system: 0.660 relative to Si=1.0e6

   Hazards

Metal ignites and burns readily..

• Lower:
• Upper:0.01

Iridium Physical Properties

 Transitional Data

• State: Solid
• Density: 22.421 g/cm3

 Molar enthalpy

• Atomization: 664.34 kJ mol-1
• Fusion: 26.4 kJ mol-1
• Vaporization: 612.1 kJ mol-1

 Transition points

• MelTing point: 2683.0 K
• Boiling point: 4403.0 K
• Critical temperature: 7800.0 K

 Molar properties

• Atomic weight: 192.22 g/mole
• Molar volume: 8.572 cm3 mol-1

 Crystal structure sequence

face-centered-cubic

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 35.48
  • Heat Capacity 25.10

• State: gas
  • Enthalpy 665.3
  • Gibbs function 617.9
  • Entropy 193.578
  • Heat Capacity 20.786

 Miscellaneous physical

• Electrical resistivity: 5.3 µ-ohms/cm
• Debye temperature: 420.0 K
• Thermal conductivity: 147.0 W / m / K
• Coefficient of linear expansion: 6.4Coef. per K
• Mass magnetic susceptibility: 1.67e-9
• X-ray diffraction mass absorption coefficients:
• CuK: 193 (µ/p)/cm2 g-1
• MoK: 110 (µ/p)/cm2 g-1

Iridium Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4 +5
• Molecular wt: 192.22 g/mole

 Radii

• Covalent: 126 pm
• Atomic: 136.0 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 68.0
• ion: +4 pm 62.5
• ion: +5 pm 57.0

 Covalent bonds

 Effective nuclear charge

• Slater: 3.90
• Clementi: 10.57
• Froese-Fischer: 15.33

 Electronegativity

• Pauling: 2.2
• Allred-Rochow: 1.55

 Standard reactions

Iridium Nuclear Properties

• Known 25
• Listed 7

• Known 182 - 198
• Listed 189 - 193

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 13.3 days
  • Decay mode: E.C.,
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 11.8 days
  • Decay mode: E.C.,
  • Source:
• Notes

• % Occ.:Natural 37.3%
• Mossbauer NRA: 13.2
• Nuclear spin/Quantum no.: 3/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 20.7 *
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 74.0 days
  • Decay mode: Beta- E.C.,
  • Source:
• Notes med

• % Occ.:Natural 62.7%
• Mossbauer NRA: 11.7
• Nuclear spin/Quantum no.: 3/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 22.3
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• Isotope Cross-section 425±15 barns

• Absolute sensitivity: 9.43e-6 1H=1.0
• Relative sensitivity: 2.53e-5 1H=1.0
• Receptivity: 0.023 13C=1.0
• Magnetogyric ratio: 0.539e7 rad / T / s
• Quadropole moment: 1.5e-28 m2
• Frequency: 1.718 MHz
• Reference:

Iridium Energy Properties

Electrons

• Ground state electron configuration: [Xe] 4f14 5d7 6s2
• Electron affinity: 190 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels