Pa occurs as chemical element in the periodic table that has the symbol Pa & atomic number 91.

Notable Characteristics
Protoactinium occurs as silver metallic element that belongs to the actinide group, with the brilliantly metal luster that it retains for a select few period in everyone's thoughts. These are superconductive at temperatures below One.Quaternary K.

Applications
Due to its scarceness, high radiation & toxicity, there are presently there is no utilizes for protoactinium outside of basic research project.

History
Protoactinium was 1st identified within 1913, when Kasimir Fajans and O. H. Göhring encountered short-lived isotope 234m-Pa, with a half-life of about 1.17 minutes, during their studies of the decay chain of 238-U. It gave a recently element a title Brevium (Latin brevis, brief, short); the title was changed to Pa within 1918 when two groups of man of science (Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of the UK) independently discovered 231-Pa, & shortened to Atomic number 91 within 1949.

Aristid V. Grosse prepared 2 mg of Pa₂O₅ in 1927, and later on managed to isolate Protactinium for the first time in 1934 from 0.1 mg of Pa₂O₅, first converting the oxide to an iodide and then cracking it in a high vacuum by an electrically heated filament by the reaction 2PaI₅ → 2Pa + 5I₂.

Within 1961, the United Kingdom Atomic Energy Authority was a cappella to make 125 g of 99.9% pure pthe, processing Lx slews of waste within a 12-stage run & spending 500,000 USD; this was the world's just supply of the element for several years to came, & these are reported that the metal was sold to laboratories for a dollars and cents of 2,800 USD / g in the as a result years.

Biological Role
Atomic number 91 doesn't play any biological role.

Occurrence
Pa occurs around pitchblende to the extent of about One part 231-Pa to 10 million of ore; ores from Zaire have about Tercet ppm.

Compounds
Known protoactinium compounds include:

Fluorides PaF₄ PaF₅ Chlorides PaCl₄ PaCl₅ Bromides PaBr₄ PaBr₅ Iodides PaI₃ PaI₄ PaI₅ Oxides PaO PaO₂ Pa₂O₅

Isotopes
Xxix radioisotopes of protactinium use at times been characterized, by having the virtually all stalls existence 231-Pa using a half life of 32760 years, 233-Pthe with a half-life of Xxvi.967 years, & 230-Pthe by owning a half-life of Seventeen.Foursome years. Tons of the leftover radioactive isotopes have half-lifes that come less than Unity.Captain hicks years, & a majority one use half lifes that come less than Single.Octad seconds. This element besides has Deuce meta states, 217m-Pa (t_½ 1.Fifteen milliseconds) & 234m-Pa (t_½ I.Seven proceedings).

A primary decay mode before the virtually all stable isotope, 231-Pa, is alpha decay and the primary mode fallowing is beta minus decay. A primary decay products before 231-Pa come element Ac (actinium) isotopes and a primary products fallowing come element U (uranium) isotopes.

Precautions
Protoactinium is each toxic & extremely radioactive; it takes precautions similar to victims utilized while treating plutonium.