Caption

Rhenium (Re). Diagram of the nuclear composition and electron configuration of an atom of rhenium-187 (atomic number: 75), the most common isotope of this element. The nucleus consists of 75 protons (red) and 112 neutrons (blue). Rhenium is a transition metal in group 7, period 6, and the d-block of the periodic table. It has a melting point of 3186 degrees Celsius. The trends across the transition metals are due to electrons filling an inner d-subshell (here, within the 5th ring), shielding the outer electrons from the increasing nuclear charge.