'Protactinium' definitions:
Definition of 'protactinium'
From: WordNet
noun
A short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead [syn: protactinium, protoactinium, Pa, atomic number 91]
Definition of 'Protactinium'
From: GCIDE
- Protactinium \Protactinium\ The radioactive chemical element, of atomic number 91; Atomic symbol Pa; at. wt. of longest-lived isotope, 231 (T1/2 = 32,500 yrs.) Also called brevium, Uranium X2 and UX2. [PJC]
Definition of 'Protactinium'
From: Elements
- Symbol: Pa
- Atomic number: 91
- Atomic weight: (231)
- Radioactive metallic element, belongs to the actinoids. The most stable isotope, Pa-231 has a half-life of 2.43*10^4 years. At least 10 other radioactive isotopes are known. No practical applications are known. Discovered in 1917 by Lise Meitner and Otto Hahn.