Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point and highest boiling point of any element. Rhenium resembles manganese chemically and is obtained as a by-product of molybdenum and copper ore's extraction and refinement. Symbol: Re
Electron configuration: Xe 4f14 5d5 6s2
Melting point: 3,182 °C
Boiling point: 5,597 °C
Atomic number: 75
Atomic mass: 186.207 ± 0.001 u