Protactinium

Name:
Protactinium
Detailed information:
A radioactive element of atomic number 91, a member of the actinide series, aw 231.0359, valences = 4, 5; 13 unstable isotopes, two of which occur naturally. Protactinium is a constituent of all uranium ores, 340 milligrams being extracted from one ton. Protactinium may also be produced by irradiation of thorium-230. Purification is carried out by ion-exchange and solvent-extraction techniques. The longest lived isotope, Pa-231, decays by α-emission and has a half-life of 33,000 years. Protactinium may be precipitated as the double potassium fluoride, K₂PaF₇, or the oxide, Pa₂O₅. The metal may be prepared by reducing PaF₄ with barium or by heating PaI₄ in a vacuum. It is hard and white, melting near 1600C. It is too rare for commercial use. Forms several compounds with halogens.

M Formula:	Pa
Hazard:
Highly toxic, radioactive material.