Polonium

Symbol: Po
Atomic number: 84
Category: metalloids
Group: 16
Period: 6
Block: p
Atomic weight: (209) g/mol
Electrons per shell: 2, 8, 18, 32, 18, 6
CAS number: 7440-08-6
Phase: solid
Density: 9.196 kg/dm³ (near room temperature)
Melting point: 527 K (254 °C, 489 °F)
Boiling point: 1235 K (962 °C, 1764 °F)
Crystal structure: cubic
Oxidation states: 4, 2
Electronegativity: 2.0 (Pauling scale)
Name's origin: Polonia
Name's meaning: the Latin name for Poland; the native land of the discoverer, Marie Curie
Facts:
- a rare and highly radioactive metalloid
- is chemically similar to bismuth and tellurium, and it occurs in uranium ores
- is unstable; all isotopes of polonium are radioactive
- is very volatile; it will almost completely vaporize at room temperatures
- has 27 known isotopes - polonium-210 is the most widely available
- is tentatively called 'Radium F'
- by mass, polonium-210 is around 250,000 times more toxic than hydrogen cyanide
- the main hazard is its intense radioactivity (as an alpha emitter), which makes it very difficult to handle safely: one gram of Po will self-heat to a temperature of around 500 °C (932 °F)
- when it is mixed or alloyed with beryllium, polonium can be a neutron source