Protactinium • Actinide Rare Earth
Symbol: Pa
Date of discovery: 1917
Name origin: Greek protos
Appearance: unknown
Discoverer: Fredrich Soddy
Obtained from: fission of uranium, thorium, plutonium
Melting point: 1873 K
Boiling point: unknown
Density[kg/m3]: 15370
Molar volume: 15.18 × 10-3 m3/mol
Protons/Electrons: 91
Neutrons: 140
Shell structure: 2,8,18,32,20,9,2
Electron configuration: [Rn]7s25f26d1
Oxidation state: 5
Crystal structure: orthorhombic
This dangerously toxic element belongs to the actinide group. It is one of the most expensive and rarest naturally-occurring elements found primarily in pitchblendes and ores from Zaire. Protactinium is an alpha-emitter and poses as a hazardous threat, similar to plutonium. The element was isolated for the fist time in 1934 by A. V. Grosse. In 1961, the United Kingdom Atomic Energy Authority was able to produce 125 grams of 99.9 percent pure protactinium which processes about sixty tons of waste material – a supply of the element that would last for many years to come.
