The electron is a chemist’s currency for controlling matter. With the introduction of quantum chemistry our understanding of the electron transformed, instigating revolutions in explaining and predicting both the characteristics of single electrons as well as how their collective behavior determines emergent properties. Elements in the sixth and seventh rows of the Periodic Table, including the lanthanides and actinides as well as heavy main-group elements, hold privileged positions with regards to this paradigm shift. Many of their fascinating properties can only be described with quantum chemistry, leading to a complex interplay of relativistic effects and magnetic phenomena that still challenges even the most advanced modeling. This complexity creates an imperative to improve chemical understanding, driving synthetic exploration informed by electronic structure characterization. Employing cutting-edge spectroscopic techniques combined with expertise in synthesizing new systems, we aim to harness these unique electrons to direct discovery of novel behaviors from molecules to extended materials.