Protactinium was identified by K. Fajans and O. Göhring in 1913 as a member of the 238U decay series. They named the new element, which was 234Pa, brevium because of the short half-life [1,3]. A more stable isotope, 231Pa with t½ = 32760 y, was discovered in 1916 by O. Hahn and L. Meither [1,3]. The metal itself was not isolated until 1934 when Aristid Grosse developed two methods. One involved reduction of the pentoxide Pa2O5 with a stream of electrons in a vacuum and the second involved heating the iodide PaI5 under vacuum [3].

Origin of name

Originally called brevium due to the short half-life of the discovered isotope. The name was changed to protoactinium as it was discovered to be the parent of actinum (from the Greek protos, meaning first). In 1949 the name was shortened to protactinium [1].