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

• Discovered in: 1839 by Mosander
• Origin of name: Greek: lanthanein, (to lie hidden)
• Historical or alternate name:

Cerite, monazite, allanite & bastnasite

Silvery white, soft metal. Readily tarnishes in air. Reaction with water releases Hydrogen gas.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.551 ppm
• Sea water: 0.0003 ppm
• Metallic meteorite: 0.236 ppm
• ConTinental crust: 16.0 ppm
• Solar photosphere: 1.13 log of abundance
• Oceanic crust: 3.7 ppm
• Solar system: 0.448 relative to Si=1.0e6

   Hazards

Metal ignites and burns readily. Reacts with oxidants. Compounds moderately toxic..

• Lower:0.01
• Upper:1.0

Lanthanum Physical Properties

 Transitional Data

• State: Solid
• Density: 6.1453 g/cm3

 Molar enthalpy

• Atomization: 431.29 kJ mol-1
• Fusion: 10.04 kJ mol-1
• Vaporization: 402.1 kJ mol-1

 Transition points

• MelTing point: 1194.0 K
• Boiling point: 3730.0 K
• Critical temperature: 10500.0 K

 Molar properties

• Atomic weight: 138.9055 g/mole
• Molar volume: 22.74 cm3 mol-1

 Crystal structure sequence

double-hex-close-packed <613 K < face-centered-cubic < 1141 K < body-centered-cubic < melTing point

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 56.9
  • Heat Capacity 27.11

• State: gas
  • Enthalpy 431.0
  • Gibbs function 393.56
  • Entropy 182.377
  • Heat Capacity 22.753

 Miscellaneous physical

• Electrical resistivity: 57.0 µ-ohms/cm
• Debye temperature: 142.0 K
• Thermal conductivity: 13.5 W / m / K
• Coefficient of linear expansion: 5.3Coef. per K
• Mass magnetic susceptibility: 1.1e-8
• X-ray diffraction mass absorption coefficients:
• CuK: 341 (µ/p)/cm2 g-1
• MoK: 45.8 (µ/p)/cm2 g-1

Lanthanum Chemical Properties

 Chemical basics:

• Oxidation states: +3
• Molecular wt: 138.9055 g/mole

 Radii

• Covalent: 169 pm
• Atomic: 187.0 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 103.2

 Covalent bonds

 Effective nuclear charge

• Slater: 2.85
• Clementi: 9.31
• Froese-Fischer: 10.43

 Electronegativity

• Pauling: 1.0
• Allred-Rochow: 1.08

 Standard reactions

Lanthanum Nuclear Properties

• Known 19
• Listed 3

• Known 126 - 144
• Listed 137 - 139

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 7/2
• Radioisotopes:
  • Half-life: 600.0 centuries
  • Decay mode: E.C.,
  • Source: reactor
• Notes

• % Occ.:Natural 0.09%
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 5/0
• Radioisotopes:
  • Half-life: 110.0 E9 years
  • Decay mode: E.C., Beta-
  • Source: reactor
• Notes

• % Occ.:Natural 99.91%
• Mossbauer NRA: 26.6
• Nuclear spin/Quantum no.: 7/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• Isotope Cross-section 8.9±0.2 barns

• Absolute sensitivity: 8.18e-5 1H=1.0
• Relative sensitivity: 9.19e-2 1H=1.0
• Receptivity: 0.43 13C=1.0
• Magnetogyric ratio: 3.5295e7 rad / T / s
• Quadropole moment: -0.47e-28 m2
• Frequency: 13.193 MHz
• Reference: 0.01M LaCl3

Lanthanum Energy Properties

Electrons

• Ground state electron configuration: [Xe] 5d1 6s2
• Electron affinity: 53 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels