• Class: Transition Metals
• Period: 5
• IUPAC group: 6
• Traditional: VIa

• Discovered in: 1778 by Scheele
• Origin of name: Greek: molybdos, (lead)
• Historical or alternate name:

Molybdenite, wulfenite & powellite

Lustrous, silvery, soft, solid metal or dark grey to black powder.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.059 ppm
• Sea water: 0.01 ppm
• Metallic meteorite: 0.920 ppm
• Continental crust: 1.0 ppm
• Solar photosphere: 2.16 log of abundance
• Oceanic crust: 1.0 ppm
• Solar system: 2.52 relative to Si=1.0e6

   Hazards

Toxic. Compounds may be toxic by inhalation..

• Lower:0.01
• Upper:1.0

Molybdenum Physical Properties

 Transitional Data

• State: Solid
• Density: 10.2 g/cm3

 Molar enthalpy

• Atomization: 656.55 kJ mol-1
• Fusion: 27.6 kJ mol-1
• Vaporization: 589.9 kJ mol-1

 Transition points

• Melting point: 2883.0 K
• Boiling point: 4912.0 K
• Critical temperature: 9450.0 K

 Molar properties

• Atomic weight: 95.94 g/mole
• Molar volume: 9.443 cm3 mol-1

 Crystal structure sequence

body-centered-cubic

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 28.66
  • Heat Capacity 24.06

• State: gas
  • Enthalpy 658.1
  • Gibbs function 612.5
  • Entropy 181.950
  • Heat Capacity 20.786

 Miscellaneous physical

• Electrical resistivity: 5.34 µ-ohms/cm
• Debye temperature: 450.0 K
• Thermal conductivity: 138.0 W / m / K
• Coefficient of linear expansion: 4.8Coef. per K
• Mass magnetic susceptibility: 1.2e-8
• X-ray diffraction mass absorption coefficients:
• CuK: 162 (µ/p)/cm2 g-1
• MoK: 18.4 (µ/p)/cm2 g-1

Molybdenum Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4 +5 +6
• Molecular wt: 95.94 g/mole

 Radii

• Covalent: 129 pm
• Atomic: 140.0 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 69.0
• ion: +4 pm 65.0
• ion: +5 pm 61.0
• ion: +6 pm 59.0

 Covalent bonds

 Effective nuclear charge

• Slater: 3.45
• Clementi: 6.98
• Froese-Fischer: 9.95

 Electronegativity

• Pauling: 1.8
• Allred-Rochow: 1.30

 Standard reactions

Molybdenum Nuclear Properties

• Known 20
• Listed 8

• Known 88 - 105
• Listed 92 - 100

• % Occ.:Natural 14.84%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life: 35.0 centuries
  • Decay mode: E.C.,
  • Source: reactor
• Notes

• % Occ.:Natural 9.25%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 15.92%
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 16.68%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 9.55%
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 24.13%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural 9.63%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• Isotope Cross-section 2.65±0.05 barns

• Absolute sensitivity: 5.07e-4 1H=1.0
• Relative sensitivity: 3.23e-3 1H=1.0
• Receptivity: 2.88 13C=1.0
• Magnetogyric ratio: 1.7433e7 rad / T / s
• Quadropole moment: 0.12e-28 m2
• Frequency: 6.514 MHz
• Reference: MoO4-2

Molybdenum Energy Properties

Electrons

• Ground state electron configuration: [Kr] 4d5 5s1
• Electron affinity: 114 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels