Synonym for protactinium ... <chemical> Protactinium. A radioactive element of the actinide group of metals. It has the atomic symbol pa, atomic number 91, and atomic weight 231. It decays by alpha-emission. ... Chemical name: Protactinium ... (12 Dec 1998) ... 
Type: Term Pronunciation: prō′ak-tin′ē-ŭm Synonyms: protactinium