Assertion: protactinium | /r/IsA | actinide
Facets:
value: on the periodic table of elements
type: LOCATION
Source sentences:
text: Since the acceptance of Glenn T. Seaborg's actinide concept in 1945, thorium, uranium and protactinium have been classified as actinides; hence, protactinium does not occupy the place of eka-tantalum (under 73) in group 5.
text: Protactinium is a very rare metallic chemical element which is classified among the actinides on the periodic table of elements.