• Class: Lanthinides
• Period: 6
• IUPAC group: 3
• Traditional: IIIa

• Discovered in: 1885 by von Welsbach
• Origin of name: Greek: prasios, (green) & didymos, (twin)
• Historical or alternate name:

Monazite & bastnasite are the chief commercial sources

Soft, malleable, Silvery metal. Reacts slowly with Oxygen. Reacts rapidly with water.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.206 ppm
• Sea water: 2e-7 ppm
• Metallic meteorite: 0.090 ppm
• ConTinental crust: 3.9 ppm
• Solar photosphere: 0.66 log of abundance
• Oceanic crust: 1.8 ppm
• Solar system: 0.174 relative to Si=1.0e6

   Hazards

Metal ignites and burns readily. Compounds moderately toxic by ingestion..

• Lower:
• Upper:

Praseodymium Physical Properties

 Transitional Data

• State: Solid
• Density: 6.773 g/cm3

 Molar enthalpy

• Atomization: 356.69 kJ mol-1
• Fusion: 11.3 kJ mol-1
• Vaporization: 357 kJ mol-1

 Transition points

• MelTing point: 1204.0 K
• Boiling point: 3785.0 K
• Critical temperature: 8900.0 K

 Molar properties

• Atomic weight: 140.90765 g/mole
• Molar volume: 20.93 cm3 mol-1

 Crystal structure sequence

double-hex-close-packed <1094 K < body-centered-cubic < melTing point

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 73.2
  • Heat Capacity 27.20

• State: gas
  • Enthalpy 355.6
  • Gibbs function 320.9
  • Entropy 189.808
  • Heat Capacity 21.359

 Miscellaneous physical

• Electrical resistivity: 68.0 µ-ohms/cm
• Debye temperature: K
• Thermal conductivity: 12.5 W / m / K
• Coefficient of linear expansion: 5.4Coef. per K
• Mass magnetic susceptibility: 4.47e-7
• X-ray diffraction mass absorption coefficients:
• CuK: 363 (µ/p)/cm2 g-1
• MoK: 50.7 (µ/p)/cm2 g-1

Praseodymium Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4
• Molecular wt: 140.90765 g/mole

 Radii

• Covalent: 165 pm
• Atomic: 182.4 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 99.0
• ion: +4 pm 85.0

 Covalent bonds

 Effective nuclear charge

• Slater: 2.85
• Clementi: 7.75
• Froese-Fischer: 10.70

 Electronegativity

• Pauling:
• Allred-Rochow: 1.07

 Standard reactions

Praseodymium Nuclear Properties

• Known 15
• Listed 2

• Known 134 - 148
• Listed 141 - 143

• % Occ.:Natural 100.0%
• Mossbauer NRA: 23.3
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 13.6 days
  • Decay mode: Beta-
  • Source: reactor
• Notes

• Isotope Cross-section 11.5±1.0 barns

• Absolute sensitivity: 0.29 1H=1.0
• Relative sensitivity: 0.29 1H=1.0
• Receptivity: 1.62e3 13C=1.0
• Magnetogyric ratio: 7.765e7 rad / T / s
• Quadropole moment: -5.9e-30 m2
• Frequency: 29.291 MHz
• Reference:

Praseodymium Energy Properties

Electrons

• Ground state electron configuration: [Xe] 4f3 6s2
• Electron affinity: <=50 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels