Discovery date : 1898
Discovered by: Marie Curie
Origin of the name: Polonium is named after Poland, the native country of Marie Curie,
who first isolated the element.
Allotropes : α-Po, β-Po
~>POLONIUM is a chemical element with symbol Po and atomic number 84. A rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth.
| FACT BOX | |||
| Group | 16 | Melting point | 254°C, 489°F, 527 K |
| Period | 6 | Boiling point | 962°C, 1764°F, 1235 K |
| Block | p | Density (g cm−3) | 9.20 |
| Atomic number | 84 | Relative atomic mass | [209] |
| State at 20°C | Solid | Key isotopes | 209Po,210Po</td> |
| Electron configuration | [Xe] 4f145d106s26p4 | CAS number | 7440-08-6 |
| ChemSpider ID | 4886482 | ChemSpider is a free chemical structure database | |
Uranium ores contain minute traces of polonium at levels of parts per billion. Despite this, in 1898 Marie Curie and husband Pierre Curie extracted some from pitchblende (uranium oxide, U3O8) after months of painstaking work. The existence of this element had been forecast by the Mendeleev who could see from his periodic table that there might well be the element that followed bismuth and he predicted it would have an atomic weight of 212. The Curies had extracted the isotope polonium-209 and which has a half-life of 103 years.
Before the advent of nuclear reactors, the only source of polonium was uranium ore but that did not prevent its being separated and used in anti-static devices. These relied on the alpha particles that polonium emits to neutralise electric charge.