|Type:Other Non-Metal, Chalcogen||Atomic weight:209|
|Density @ 293 K:9.4 g/cm3||Atomic volume:22.23 cm3/mol|
Polonium, also called Radium F, was the first element discovered by Marie S. Curie. She discovered it in 1898 while investigating radioactivity in pitchblende (uranium oxide). The element is named after Poland, the country of Curie's birth.
|State (s, l, g):solid|
|Melting point: 527 K (254 °C)||Boiling point:1233 K (960 °C)|
|Specific heat capacity: 0.12 J g-1 K-1||Heat of atomization: 142 kJ mol-1|
|Heat of fusion:13 kJ mol-1||Heat of vaporization : 120 kJ mol-1|
|1st ionization energy:812 kJ mol-1||2nd ionization energy:kJ mol-1|
|3rd ionization energy:kJ mol-1||Electron affinity:180 kJ mol-1|
|Shells: 2,8,18,32,18,6||Electron configuration:[Xe] 4f14 5d10 6s2 6p4|
|Minimum oxidation number:-2||Maximum oxidation number:6|
|Min. common oxidation no.:-2||Max. common oxidation no.:4|
|Electronegativity (Pauling Scale):2.0||Polarizability volume: 6.8 Å3|
Polonium is harmful both through its chemical toxicity and its radioactivity. Exposure to polonium increases the risk of getting various cancers.
Polonium is a rare, silvery-gray, radioactive low-melting metalloid. Polonium readily reacts with dilute acids, but only slightly with alkalis. All of its isotopes are radioactive. 210Po emits a blue glow, as the air around it is excited by the decay products. 1 gram of Po emits as many alpha particles as 5 kilograms of radium. The energy released by polonium's alpha decay is considerable and heats the volume around it. The energy released is so large (140 W/g) that a capsule containing about half a gram reaches a temperature above 500 °C.
Polonium is used to eliminate static electricity produced during processes such as rolling paper, wire and sheet metal. However, beta decay sources are more commonly used as they are less dangerous. 210Po can be used as an atomic heat source but because of the isotope's short half-life (138.4 days), it doesn't provide power for long-term uses. Polonium is also used in anti-static brushes to eliminate dust on photographic film. It is sealed in brushes to control the radioactive emissions.
|Reaction with air:mild, ⇒ PoO2||Reaction with 6 M HCl:mild, ⇒ PoCl2|
|Reaction with 15 M HNO3:||Reaction with 6 M NaOH:|
|Atomic radius:190 pm||Ionic radius (1+ ion):pm|
|Ionic radius (2+ ion):pm||Ionic radius (3+ ion):pm|
|Ionic radius (2- ion):pm||Ionic radius (1- ion):pm|
|Thermal conductivity: 0.2 W m-1 K-1||Electrical conductivity: 0.7 x 106 S m-1|
|Abundance earth's crust:part per billion by weight, parts per billion by moles|
|Abundance solar system:parts per billion by weight, part per billion by moles|
|Cost, pure: $24 per 100g|
|Cost, bulk:$ per 100g|
Polonium is a very rare element due to the short half-life of all its isotopes. It is found in uranium ores in minute quantities. It can be obtained by bombarding natural bismuth, 209Bi , with neutrons to give 210Bi, which then decays to 210Po via β decay.
Polonium has 29 isotopes whose half-lives are known, with mass numbers 190 to 218. None are stable. The most stable isotope is 209Po, with a half-life of 102 years.