Assertion: technetium | /r/HasProperty | discovered
Facets:
Source sentences:
text: Technetium was predicted long before it was actually discovered.
text: Dmitri Mendeleev predicted an element forty-three in his periodic table nearly seventy years before technetium was discovered.
text: Technetium was discovered and first isolated by Emilio Segrè and Carlo Perrier in 1937.