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

• Discovered in: 1802 by Ekeberg
• Origin of name: Greek: mythological Tantalos
• Historical or alternate name:

Columbite-tantalite (Fe, Mn)(Nb, Ta)2 O2

Soft, Silvery shiny metal. Exposed surfaces form corrosion resistant oxide film. Attacked by HF and fused alkalis.

• Atmosphere: ~0.0 ppm
• Primitive mantle: 0.04 ppm
• Sea water: 0.0025 ppm
• Metallic meteorite: 0.017 ppm
• ConTinental crust: 1.0 ppm
• Solar photosphere: ~0.0 log of abundance
• Oceanic crust: 0.3 ppm
• Solar system: 0.0226 relative to Si=1.0e6

   Hazards

Metal ignites in air. Compounds moderately toxic by ingestion..

• Lower:
• Upper:0.01

Tantalum Physical Properties

 Transitional Data

• State: Solid
• Density: 16.6 g/cm3

 Molar enthalpy

• Atomization: 781.425 kJ mol-1
• Fusion: 31.4 kJ mol-1
• Vaporization: 758.22 kJ mol-1

 Transition points

• MelTing point: 3269.0 K
• Boiling point: 5698.0 K
• Critical temperature: 10250.0 K

 Molar properties

• Atomic weight: 180.9479 g/mole
• Molar volume: 10.919 cm3 mol-1

 Crystal structure sequence

body-centered-cubic

 Thermodynamics

• State: solid
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 41.51
  • Heat Capacity 25.36

• State: gas
  • Enthalpy 782.0
  • Gibbs function 739.3
  • Entropy 185.214
  • Heat Capacity 20.857

 Miscellaneous physical

• Electrical resistivity: 13.15 µ-ohms/cm
• Debye temperature: 240.0 K
• Thermal conductivity: 57.5 W / m / K
• Coefficient of linear expansion: 6.3Coef. per K
• Mass magnetic susceptibility: 1.07e-8
• X-ray diffraction mass absorption coefficients:
• CuK: 166 (µ/p)/cm2 g-1
• MoK: 95.4 (µ/p)/cm2 g-1

Tantalum Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4 +5
• Molecular wt: 180.9479 g/mole

 Radii

• Covalent: 134 pm
• Atomic: 147.0 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 72.0
• ion: +4 pm 68.0
• ion: +5 pm 64.0

 Covalent bonds

 Effective nuclear charge

• Slater: 3.30
• Clementi: 9.53
• Froese-Fischer: 13.78

 Electronegativity

• Pauling: 1.5
• Allred-Rochow: 1.33

 Standard reactions

Tantalum Nuclear Properties

• Known 18
• Listed 6

• Known 172 - 186
• Listed 179 - 183

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 7/2
• Radioisotopes:
  • Half-life: 665.0 days
  • Decay mode: E.C.,
  • Source:
• Notes

• % Occ.:Natural 0.012%
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 8/0
• Radioisotopes:
  • Half-life: 1.0 E13 years
  • Decay mode: E.C., Beta-
  • Source:
• Notes

• % Occ.:Natural 99.988%
• Mossbauer NRA: 0.99 *
• Nuclear spin/Quantum no.: 7/2
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 21.80
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 114.0 days
  • Decay mode: Beta-
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 5.0 days
  • Decay mode: Beta-
  • Source:
• Notes

• Isotope Cross-section 22±1 barns

• Absolute sensitivity: 3.60e-2 1H=1.0
• Relative sensitivity: 3.60e-2 1H=1.0
• Receptivity: 204 13C=1.0
• Magnetogyric ratio: 3.2073e7 rad / T / s
• Quadropole moment: 3.e-28 m2
• Frequency: 11.970 MHz
• Reference: TaF6-

Tantalum Energy Properties

Electrons

• Ground state electron configuration: [Xe] 4f14 5d3 6s2
• Electron affinity: 14 kJ mol-1
• Filling orbitals:

Spectral lines

 Ionization energies

 Atomic energy levels