• Class: Inert Gases
• Period: 3
• IUPAC group: 18
• Traditional: 0

• Discovered in: 1894 by Rayleigh, Ramsay
• Origin of name: Greek: argos, (inactive)
• Historical or alternate name:

0.94% of air

Colorless, odorless non-reactive gas. Chemically inert.

• Atmosphere: 9300 ppm
• Primitive mantle: ~0.0 ppm
• Sea water: 0.6 ppm
• Metallic meteorite: 751.0 ppm
• Continental crust: 1.2 ppm
• Solar photosphere: 6.0 log of abundance
• Oceanic crust: ~0.0 ppm
• Solar system: 1.040E+5 relative to Si=1.0e6

   Hazards

Inert nonflammable gas. Asphyxiant..

   Human daily limits

• Lower:
• Upper:

Argon Physical Properties

 Transitional Data

• State: Gas
• Density: 1.784 g/L

 Molar enthalpy

• Atomization: 0.0 kJ mol-1
• Fusion: 1.21 kJ mol-1
• Vaporization: 6.53 kJ mol-1

 Transition points

• Melting point: 84.0 K
• Boiling point: 87.5 K
• Critical temperature: 150.8 K

 Molar properties

• Atomic weight: 39.948 g/mole
• Molar volume: 20.890 cm3 mol-1

 Crystal structure sequence

face-centered-cubic

 Thermodynamics

• State: gas
  • Enthalpy 0
  • Gibbs function 0
  • Entropy 154.843
  • Heat Capacity 20.786

 Miscellaneous physical

• Electrical resistivity: µ-ohms/cm
• Debye temperature: 92.0 K
• Thermal conductivity: 0.0179 W / m / K
• Coefficient of linear expansion: Coef. per K
• Mass magnetic susceptibility: -6.16e-9
• X-ray diffraction mass absorption coefficients:
• CuK: 123 (µ/p)/cm2 g-1
• MoK: 13.5 (µ/p)/cm2 g-1

Argon Chemical Properties

 Chemical basics:

• Oxidation states: 0
• Molecular wt: 39.948 g/mole

 Radii

• Covalent: pm
• Atomic: 188.0 pm
• Van der Waals: 191 pm

 Ions:

 Covalent bonds

 Effective nuclear charge

• Slater: 6.75
• Clementi: 6.76
• Froese-Fischer: 7.52

 Electronegativity

• Pauling:
• Allred-Rochow:

 Standard reactions

Argon Nuclear Properties

• Known 8
• Listed 6

• Known 35 - 42
• Listed 36 - 42

• % Occ.:Natural 0.337%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 35.0 days
  • Decay mode: E.C.,
  • Source: Cosmic irradiation
• Notes

• % Occ.:Natural 0.063%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 7/2
• Radioisotopes:
  • Half-life: 269.0 years
  • Decay mode: Beta-
  • Source: Cosmic irradiation.
• Notes date

• % Occ.:Natural 99.600%
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life:
  • Decay mode:
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.:
• Radioisotopes:
  • Half-life: 33.0 years
  • Decay mode: Beta-
  • Source:
• Notes

• Isotope Cross-section 0.650±0.030 barns

Argon Energy Properties

Electrons

• Ground state electron configuration: [Ne] 3s2 3p6
• Electron affinity: -35 kJ mol-1
• Filling orbitals:

 Ionization energies

 Atomic energy levels