Ruthenium is a hard, brittle, and light gray multivalent rare metal with the element symbol Ru and an atomic number of 44. It is classified in Group VIII of the fifth period and belongs to the d-block metals. As a member of the platinum group metals, ruthenium is one of the rarest metals, with a crustal abundance of only one part per billion. Ruthenium crystals adopt a hexagonal lattice structure, possessing a melting point of 2334 °C, a boiling point of 4150 °C, a density of 12.45 g/cm³ at room temperature, an atomic radius of 133 pm, and a first ionization energy of 710.2 kJ·mol⁻¹ . It exhibits remarkable stability and strong corrosion resistance, enduring the corrosion of hydrochloric acid, sulfuric acid, nitric acid, and aqua regia even at room temperature. Ruthenium finds extensive applications in electronic information, pharmaceuticals, electrochemistry, and other fields. Additionally, ruthenium and its complexes exhibit excellent catalytic activity, making them useful as catalysts in various chemical reactions.