Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; and its exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.
The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the original name of the metal was сyprium (metal of Cyprus), later shortened to сuprum. Its compounds are commonly encountered as copper(II) salts, which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina). Decorative art prominently features copper, both by itself and as part of pigments.
Copper was one of the first metals to be processed into implements and the first metal to be smelted from ores. Its excellent ductility and high conductivity assure its use in modern society.The CAS number is 7440-50-8, the molecular formula is Cu and the molecular weight is 63.55 g/mol.