Cover story of this week's issue of Nature
The most dramatic modern revision of the Mendeleev’s periodic table of elements came in 1944, when Glenn T. Seaborg placed a new series of elements, the actinides (atomic numbers 89–103), below the lanthanides. In this issue our report on the first measurement of one of the basic atomic properties of element 103 (lawrencium), its first ionization potential, is included. Lawrencium is accessible only as short-lived isotopes via atom-at-a-time synthesis in heavy-ion accelerators, so experimental investigations of its properties rare. The experimental results, agreeing with state-of-the-art theoretical calculations, show that the last valence electron in lawrencium is the most weakly-bound one in all actinides and any other element beyond group 1 of the periodic table. This signature confirms the end of the actinide series at element 103 and validates the architecture of the periodic table in this region, where relativistic effects play a crucial role.
Article:
"News & Views" by Prof. Andreas Türler:
Nuclear chemistry: Lawrencium bridges a knowledge gap
Nature 520, 166-167 (2015)