Americium

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Atomic symbol: Am

Atomic number: 95

Atomic weight: (243)

Atomic volume: 17.86 cm³/mol

Density: 13.6 g/cm³

Period Number: 7

Group number: none

Group name: Rare Earth, Actinides

Element classification: Metal

States

Phase at room temperature: Solid

Melting Point: 1267.2 K

Boiling point: 2873 K

Heat of fusion: 14.40 kJ/mol

Heat of vaporization: ?

Energies

Ionization Energy: 5.993 eV

1st ionization energy: 578 kJ/mole

2nd ionization energy: kJ/mole

3rd ionization energy: kJ/mole

Electronegativity: 1.3

Electron affinity: kJ/mole

Specific heat: 0.11 J/gK

Heat atomization: kJ/mole atoms

Oxidation & Electrons

Shells: 2,8,18,32,25,8,2

Electron Shell Configuration: [Rn] 5f7 7s2

Minimum oxidation number: 0

Maximum oxidation number: 6

Minimum common oxidation number: 0

Maximum common oxidation no: 3

Appearance & Characteristics

Structure:: fcc: face-centered cubic

Color: silvery-white

Hardness: mohs

Toxicity: ?

Characteristics: Radioactive

Uses: smoke detector

Reactions

Reaction with air: ?

Reaction with 6M HCl: ?

Reaction with 15M HNO3: ?

Reaction with 6M NaOH: ?

Other Forms

Number of isotopes: 0

Oxide(s): AmO Am₂O₃ AmO₂

Hydride(s): AmH₂ AmH₃

Chloride(s): AmCl₂ AmCl₃

Radius

Atomic Radius: 173 pm

Ionic radius (1- ion): pm

Ionic radius (1+ ion): pm

Ionic radius (2- ion): pm

Ionic radius (2+ ion): pm

Ionic radius (3+ ion): 111.5 pm

Conductivity

Thermal conductivity: J/m-sec-deg

Electrical conductivity: 1/mohm-cm

Polarizability: 23.3 A^3

Abundance

Source: Synthetic

Relative abundance solar system: log

Abundance earth's crust: log

Estimated crustal abundance: Not Applicable

Estimated oceanic abundance: Not Applicable

History

(the Americas) Americium was the fourth transuranic element to be discovered; the isotope ²⁴¹Am was identified by Seaborg, James, Morgan, and Ghiorso late in 1944 at the wartime metallurgical laboratory at the University of Chicago as the result of successive neutron capture reactions by plutonium isotopes in a nuclear reactor.

Sources

Properties

The luster of freshly prepared americium metal is white and more silvery than plutonium or neptunium prepared in the same manner. It appears to be more malleable than uranium or neptunium and tarnishes slowly in dry air at room temperature. Americium must be handled with great care to avoid personal contamination. The alpha activity from ²⁴¹Am is about three times that of radium. When gram quantities of ²⁴¹Am are handled, the intense gamma activity makes exposure a serious problem. ²⁴¹Am has been used as a portable source for gamma radiography. It has also been used as a radioactive glass thickness gauge for the flat glass industry and as a source of ionization for smoke detectors.