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Element Fact
Americium is one of the few radioactive elements that find its use in homes as a smoke detector.

Polonium, Po

polonium sample

Atomic number: 84
Atomic mass: [209] (no stable nuclide)
Natural abundance: -
209Po (208.982416) - *%

History and Production

The word polonium was derived from the country Poland. It was discovered in 1898 by Marie Curie by processing huge quantities of uranium ore. The element was separated by then newly discovered phenomenon of radioactivity. She was subsequently awarded the Nobel Prize for chemistry in 1911. The metal cannot be obtained from natural source due to short half life of the metal. The isotope 210Po (half-life = 138 days) can be prepared by neutron bombardment of pure 209Bi in a nuclear reactor. It is a strong a-emitter used for thermoelectric power. Other isotopes such as 209Po (half life=102 years) and 208Po (half life=2.9 years) can be prepared by alpha or proton bombardment of lead or bismuth in a cyclotron. Metallic polonium can be mixed with beryllium to provide a source of neutrons.

Physical Data

The 210Po is a low melting point and fairly volatile metal. Two allotropic modifications are known to exist. It is extremely harmful to the body due to damage arises from the adsorption of the energy of the a particle into tissue.

Interatomic distance: 334.6 pm
Melting point: 254C
Boiling point: 962C
Thermal conductivity/Wm-1K-1: 20 (27C)
Density/kgm-3: 9320 (a, 20C)

Standard Thermodynamic Data (atomic gas)

Enthalpy of formation: -
Gibbs free energy of formation: -
Entropy: -
Heat capacity: -

Electronic data

Electronic configuration: [Xe] 4f14 5d10 6s2 6p4
Term symbol: 3P2
Electron affinity: 183.3223 kJ/mol   Electronegativity (Pauline): 2.00
Ionization energy (first, second, third): 812.118, -, - kJ/mol

Chemical properties

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