Lutetium, role

Another aspect, still under discussion, is the identity of the element that should be considered the homologue of yttrium in group 3. This role is usually assigned to lanthanum, with the series of lanthanides going from cerium to lutetium. However, there are also reasons to put lutetium in group 3, as the homologue of yttrium, and thus begin the series of lanthanides with lanthanum. ... 

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