Книга: Rhenium: Chemical Element, Atomic Number, Transition Metal, Group 7 Element, Periodic Table, Parts-per Notation, Manganese

High Quality Content by Wikipedia articles! 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 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 of any element, exceeded only by tungsten and carbon. Rhenium resembles manganese chemically and is obtained as a by-product of molybdenum and copper refinement. Rhenium shows in its compounds a wide variety of oxidation states ranging from ?1 to +7. Discovered in 1925, rhenium was the last naturally occurring stable element to be discovered (francium was the last identified naturally-occurring element, but it is unstable). Rhenium was named after the river Rhine.