84 Po (Polonium)
Appearance: Silvery
Allotropes: α-Po, β-Po
Mass number: 209
Atomic weight: 208.9824 g/mol
Atomic number (Z): 84
Electrons: 84
Protons: 84
Neutrons: 126
Group: 16
Period: 6
Block: P
Element category: Metalloids (semi-metal)
Electrons per shell: K2, L8, M18, N32, O8, P6
Electron configuration: 1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p4
Phase: Solid
Melting point: 527 K (254 oC)
Boiling point: 1235 K (962 oC)
Density: α: 9.196 g/cm3, β: 9.398 g/cm3
Molar volume: 0.00002273 m3/mol
Half life(s): 322×107
Lifetime(s): 464×107
Decay mode: α decay
Neutron cross section (Barns): 0.5
Heat of fusion: ca. 13 kJ/mol
Heat of vaporization: 102.91 kJ/mol
Molar heat capacity: 26.4 J/(mol∙K)
Oxidation states: 6, 5, 4, 2, -2
Ion charge: Po2+, Po4+
Electronegativity: Pauling scale: 2.0
Valence: 6
Electron affinity: 183.3 kJ/mol
Ionization energies: 1st: 812.1 kJ/mol
Atomic radius: empirical: 168 pm
Covalent radius: 140±4 pm
Vander waals radius: 197 pm
Crystal structure: Cubic (α-Po), Rhombohedral (β-Po)
Grid parameters: 3.35 Å
Electrical conductivity: 2300000 S/m
Electrical type: Conductor
Resistivity: 4.3×10-7 Ω-m
Thermal expansion: 23.5 μm/(m∙K)
Thermal conductivity: 20 W/(m∙K)
Magnetic ordering: nonmagnetic
CAS Number: 7440-08-6
Naming: After Polonia (Homeland of Marie Curie)
Discovery: Pierre and Marie Curie (1898)
First isolation: Willy Marckwald (1902)
Isotopes: 208Po 209Po 210Po
Polonium Uses:
It is an Alpha-emitter, used in antistatic device, It is used as source of heat (single gram of polonium will reach a 500 oC as a result of α radiation emitted)
It can be mixed or alloyed with beryllium to provide a source of neutrons.
Biological role of Polonium:
It is highly toxic due to its radioactivity.
Natural abundance of Polonium:
It is found in Uranium ores. It is obtained by bombarding bismuth-209 with neutrons to give bismuth-210.
#polonium
