Protactinium
Pa is dense, greenish -gray metal which reacts with water vapor, inorganic acids and oxygen. From the Greek word for first, protos, and the element actinium, which combined together means "the parent of actinium." Protactinium is one of the rarest and most expensive naturally occurring elements.
Physical and orbital Properties
Protactinium is an element on the periodic table with the symbol of Pa and atomic number (protons) of 91. With an atomic weight of 231.03588, melting point of 1845 K (1572°C or 2862°F). It has a density of 15.37 grams per cubic centimeter. Protactinium is a solid at room temperature. It is superconductive at temperatures below 1.4 K. It’s classified as a metal and it’s in the group actinide 7 and period 7. Has a ground state electron configuration of [Rn].5f2.6d1.7s2, shell structure of 2.8.18.32.20.9.2 and the term symbol is 4k 11/12. Pauling electronegativity of 1.5 Pauling units and first ionization energy of 568 kJ mol-1. Protactinium is known to be highly radioactive and toxic.
History
Mendeleev predicted there would be an element between thorium and uranium. Protactinium was first discovered by Kasimir Fajans and O.H. Gohring in 1913 while they were studying uranium's decay chain. Their work was interrupted by the First World War. They first found the isotope protactinium – 234, which had a half-life of about 1.17 minutes. When they first came across it they named it brevium and they continued their studies of this element. The existence of Pa was confirmed in 1918 when isotope protactinium- 231 discovered by scientists Otto Hahn, Lise Meitner of Germany, Frederick Soddy and John Cranston of Great Britain. They identified protactinium-231 by establishing that no known substance could have emitted the alpha particles that were observed and by the actinium produced. Then Pa was first isolated by a scientist called Aristid V. Grosse in 1934. He isolated the element Pa from the oxide by converting it to the iodide and then decomposed it using a heated filament in a high vacuum. Grosse involved reduction of the pentoxide with a stream of electrons in a vacuum.
Uses/ Interesting facts
Protactinium is a rare, toxic and expensive element that is present in uranium ores in very small amounts. In 1961, the Great Britain Atomic Energy Authority produced 125 grams of 99.9% pure protactinium. They had to process about 55,000 kilograms of ore and spend about half a million to get it. Protactinium is barely used because it’s highly radioactive and toxic and has no biological role. It is produced in gram quantities from uranium fuel elements.
Atomic Data/ Oxidation States/Isotopes
Pa