Assertion: hafnium | /r/PartOf | same group
Facets:
value: in the periodic table
type: LOCATION
Source sentences:
text: The reason it took over half a century to discover Hf after its existence had first been predicted, and why the analytical approach chosen was that of X-ray spectroscopy and not wet chemistry, is that Hf so closely resembles Zr chemically (because of having the same number of valence electrons, nearly the same ionic radius, and belonging to the same group in the periodic table) that it is extremely difficult to separate the two in the chemistry laboratory (although this was eventually accomplished the year after Hf’s initial discovery by X-ray spectroscopy).