• Class: Transition Metals
• Period: 6
• IUPAC group: 8
• Traditional: VIII

• Discovered in: 1803 by Tennant
• Origin of name: Greek: osme, (smell)
• Historical or alternate name:

Iridosmine, plaTinum sands & Nickel ores

Lustrous Silvery metal. Unaffected by air, water and acids. Characteristic acrid, Chlorine like odor due to tetroxide compound.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.0038 ppm
• Sea water: trace ppm
• Metallic meteorite: 0.699 ppm
• ConTinental crust: 0.005 ppm
• Solar photosphere: 0.7 log of abundance
• Oceanic crust: <4.0e-6 ppm
• Solar system: 0.717 relative to Si=1.0e6

   Hazards

Irritant. Compounds generally moderate toxicity. Osmium tetroxide highly toxic..

• Lower:
• Upper:0.01

Osmium Physical Properties

 Transitional Data

• State: Solid
• Density: 22.48 g/cm3

 Molar enthalpy

• Atomization: 791.0 kJ mol-1
• Fusion: 29.3 kJ mol-1
• Vaporization: 738.06 kJ mol-1

 Transition points

• MelTing point: 3318.0 K
• Boiling point: 5300.0 K
• Critical temperature: 12700.0 K

 Molar properties

• Atomic weight: 190.2 g/mole
• Molar volume: 8.476 cm3 mol-1

 Crystal structure sequence

hexagonal-close-packed

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 32.6
  • Heat Capacity 24.7

• State: gas
  • Enthalpy 791
  • Gibbs function 745
  • Entropy 192.573
  • Heat Capacity 20.786

 Miscellaneous physical

• Electrical resistivity: 9.5 µ-ohms/cm
• Debye temperature: 500.0 K
• Thermal conductivity: 87.6 W / m / K
• Coefficient of linear expansion: 5.1Coef. per K
• Mass magnetic susceptibility: 6.5e-10
• X-ray diffraction mass absorption coefficients:
• CuK: 186 (µ/p)/cm2 g-1
• MoK: 106 (µ/p)/cm2 g-1

Osmium Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4 +5 +6 +7
• Molecular wt: 190.2 g/mole

 Radii

• Covalent: 126 pm
• Atomic: 135.0 pm
• Van der Waals: pm

 Ions:

• ion: +4 pm 63.0
• ion: +5 pm 57.5
• ion: +6 pm 54.5
• ion: +7 pm 52.5

 Covalent bonds

 Effective nuclear charge

• Slater: 3.75
• Clementi: 10.32
• Froese-Fischer: 14.90

 Electronegativity

• Pauling: 2.2
• Allred-Rochow: 1.52

 Standard reactions

Osmium Nuclear Properties

• Known 19
• Listed 12

• Known 181 - 195
• Listed 184 - 194

• % Occ.:Natural 0.02%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 94.0 days
  • Decay mode: E.C.,
  • Source:
• Notes

• % Occ.:Natural 1.58%
• Mossbauer NRA: 22.0 *
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 2.0 E15 years
  • Decay mode: alpha,
  • Source:
• Notes

• % Occ.:Natural 1.60%
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 1/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 13.30%
• Mossbauer NRA: 24.8
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 16.10%
• Mossbauer NRA: 5.8
• Nuclear spin/Quantum no.: 3/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 11.2
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 15.3
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 26.40%
• Mossbauer NRA: 29.9
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 15.4 days
  • Decay mode: Beta-
  • Source:
• Notes

• % Occ.:Natural 41.00%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 6.0 years
  • Decay mode: Beta-
  • Source:
• Notes

• Isotope Cross-section 15.3±0.7 barns

• Absolute sensitivity: 2.00e-7 1H=1.0
• Relative sensitivity: 1.22e-5 1H=1.0
• Receptivity: 1.14e-3 13C=1.0
• Magnetogyric ratio: 0.6105e7 rad / T / s
• Quadropole moment: m2
• Frequency: 2.282 MHz
• Reference: OsO4

Osmium Energy Properties

Electrons

• Ground state electron configuration: [Xe] 4f14 5d6 6s2
• Electron affinity: 139 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels