The metallic element americium is not found in nature. Instead, it is produced inside nuclear reactors when uranium or plutonium atoms are bombarded with neutrons. Surprisingly, americium is the most commonly used radioactive element in the home. The radioactivity emitted by americium atoms causes the air inside smoke detectors to conduct electricity. When the smoke interrupts the electrical current, an alarm sounds.

Summary of properties (Am)

Atomic weight[243]
Discoverer (year)Seaborg, Glenn T. (1944)
Natural formmetallic solid (hexagonal)
Electron configuration[Rn] 57 7s2
Melting point (ºC)994
Boiling point (ºC)2607
Abundance in earth's crust (ppm)synthetic
Isotope (abundance)
Density g/cm319.84
Van der Waals radius (pm)244
Covalent radius (pm)173
Electronegativity (Pauling)1.3
Vaporization enthalpy (kJ/mol)-
Enthalpy of fusion (kJ/mol)14.39
Specific heat capacity (J/g·K) at 25ºC and 1 atm-
Thermal conductivity (W/cm·K) at 25ºC and 1 atm-
Oxidation state+6, +5, +4, +3
Electron affinity (eV)
1st Ionization potential (eV)5.9738

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