Caption

Ytterbium (Yb). Diagram of the nuclear composition and electron configuration of an atom of ytterbium-174 (atomic number: 70), the most common isotope of this element. The nucleus consists of 70 protons (red) and 104 neutrons (blue). Ytterbium is a lanthanide in period 6, and the f-block of the periodic table. It melts at 824 degrees Celsius. The trend across the lanthanide series arises from the failure of electrons filling an inner f-subshell (here, within the 4th ring) to shield outer electrons from increasing nuclear charge.