Pa Protactinium 91 231.03588 7 f 91 1570.0 4000.0 [Rn] 5f2 6d1 7s2 2 8 18 32 20 9 2 15.4 9.9E-13% Silver Orthorhombic 1.5 {"1":"568"} 568 +5,4 1.61 15.0 47.0 1 32788 y 47279.y AlphaEmission Solid, Conductor, Actinide, Radioactive, Natural PRO-tak-tin-eh-em Very rare, silvery-white, extremely radioactive metal. It has no significant commercial applications. Does not occur in nature. Found among fission products of uranium, thorium, and plutonium. 3nZB4u34q98 Protactinium

In 1908, Japanese chemist Masataka Ogawa announced that he discovered the 43rd element.

However, later analysis indicated the presence of rhenium (element 75), not element 43.

In 1922, Walter Noddack, Ida Eva Tacke and Otto Berg announced its separation from gadolinite and gave it the present name. From the Latin word Rhenus meaning Rhine 91 1913 Otto Hahn, Lise Meitner, Frederick Soddy, John Cranston Germany, England From the Greek word "protos" meaning "first"

Very little is known about the toxicity of rhenium

Chile has the world's largest rhenium reserves

Rhenium is widely used as filaments for mass spectrographs and ion gauges.

It is also used with platinum as catalysts in the production of lead-free, high-octane gasoline.

Nickel-based superalloys of rhenium are used in the combustion chambers, turbine blades, and exhaust nozzles of jet engines.