• Class: Trans-Uranium AcTinides
• Period: 7
• IUPAC group: 3
• Traditional: IIIa

• Discovered in: 1944 by Seaborg et. al.
• Origin of name: The Americas
• Historical or alternate name:

Silvery metal. Resists alkalis; reacts with acids, attacked by air and steam.

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

   Hazards

Poison. Radioactive. Toxic by inhalation..

• Lower:
• Upper:

Americium Physical Properties

 Transitional Data

• State: Solid
• Density: 13.67 g/cm3

 Molar enthalpy

• Atomization: 266.0 kJ mol-1
• Fusion: 14.4 kJ mol-1
• Vaporization: 238.5 kJ mol-1

 Transition points

• MelTing point: 1267.0 K
• Boiling point: 2880.0 K
• Critical temperature: 10800.0 K

 Molar properties

• Atomic weight: 243.0614 g/mole
• Molar volume: 17.74 cm3 mol-1

 Crystal structure sequence

double-hex-close-packed <923 K < face-centered-cubic < 1350 K < body-centered-cubic < melTing point

 Thermodynamics

 Miscellaneous physical

• Electrical resistivity: 90.0 µ-ohms/cm
• Debye temperature: K
• Thermal conductivity: W / m / K
• Coefficient of linear expansion: Coef. per K
• Mass magnetic susceptibility: 5e-8
• X-ray diffraction mass absorption coefficients:
• CuK: (µ/p)/cm2 g-1
• MoK: (µ/p)/cm2 g-1

Americium Chemical Properties

 Chemical basics:

• Oxidation states: +3 +4 +5 +6
• Molecular wt: 243.0614 g/mole

 Radii

• Covalent: pm
• Atomic: 173.0 pm
• Van der Waals: pm

 Ions:

• ion: +3 pm 97.5
• ion: +4 pm 85.0

 Covalent bonds

 Effective nuclear charge

• Slater: 1.3
• Clementi:
• Froese-Fischer: 4.65

 Electronegativity

• Pauling:
• Allred-Rochow:

 Standard reactions

Americium Nuclear Properties

• Known 13
• Listed 2

• Known 237 - 247
• Listed 241 - 243

• % Occ.:Natural
• Mossbauer NRA:
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life: 433.0 years
  • Decay mode: alpha, S.F.
  • Source:
• Notes

• % Occ.:Natural
• Mossbauer NRA: 13.4
• Nuclear spin/Quantum no.: 5/2
• Radioisotopes:
  • Half-life: 73.7 years
  • Decay mode: alpha, S.F.
  • Source:
• Notes

• Isotope 243Cross-section 180±20 barns

• Absolute sensitivity: 1H=1.0
• Relative sensitivity: 1H=1.0
• Receptivity: 13C=1.0
• Magnetogyric ratio: 1.54e7 rad / T / s
• Quadropole moment: 4.9e-28 m2
• Frequency: 5.76 MHz
• Reference:

Americium Energy Properties

Electrons

• Ground state electron configuration: [Rn] 5f7 7s2
• Electron affinity: kJ mol-1
• Filling orbitals:

 Ionization energies

 Atomic energy levels