A Rare-Earth Metal Retrospective to Stimulate All Fields.

Formulating insightful questions and experiments is crucial to the advancement of science. The purpose of this Perspective is to encourage scientists in all areas of chemistry to ask more "What if?" questions: What if we tried this experiment? What if we used these conditions? What if that idea is not correct? To stimulate this thinking, a retrospective analysis of a specific field, in this case rare-earth metal chemistry, is presented that describes the "What if?" questions that could have and should have been asked earlier based on our current knowledge. The goal is to provide scientists with a historical perspective of discovery that exemplifies how previous views in chemistry were often narrowed by predominant beliefs in principles that were incorrect. The same situation is likely to exist today, but we do not realize the limitations! Hopefully, this analysis can be used as a springboard for posing important "What if?" questions that should be asked right now in every area of chemical research.