21. The hydrolytic properties of pentavalent protactinium are close to those of tantalum ( V ) and niobium ( V ). 22. One process suggested for both separation of protactinium and the removal of the lanthanides is the contact with molten bismuth. 23. Fluorides, phosphates, hypophosphate, iodate and phenylarsonates of protactinium ( IV ) are insoluble in water and dilute acids. 24. He used two different procedures : in the first one, protactinium oxide was irradiated by 35 keV electrons in vacuum. 25. The new name meant " parent of actinium " and reflected the fact that actinium is a product of radioactive decay of protactinium . 26. Much smaller trace amounts of the short-lived nuclear isomer protactinium -234m occur in the decay chain of uranium-238. 27. Protactinium carbide PaC is formed by reduction of protactinium tetrafluoride with barium in a carbon crucible at a temperature of about 1400 �C.28. Protactinium carbide PaC is formed by reduction of protactinium tetrafluoride with barium in a carbon crucible at a temperature of about 1400 �C. 29. The isotopes of neptunium range in atomic weight from 225.0339 protactinium , and the primary products after are isotopes of plutonium. 30. The most abundant, or easily synthesized actinides are uranium and thorium, followed by plutonium, americium, actinium, protactinium and neptunium.
