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Copper is one of the few metals that can occur in nature in a directly usable metallic form. This means that copper is a native metal. This led to very early human use in several regions, from c. 8000 BC.
Example of a copper alloy object: a Neo-Sumerian "Foundation Nail" of Gudea, circa 2100 BC, made in the lost-wax cast method, overall: 17.5 x 4.5 x 7.3 cm, probably from modern-day Iraq, now in the Cleveland Museum of Art (Cleveland, Ohio, USA) Copper alloys are metal alloys that have copper as their principal component.
Classic examples are metals such as copper and aluminum, but some materials are metals in an electronic sense but have negligible metallic bonding in a mechanical or thermodynamic sense (see intermediate forms). Metallic solids have, by definition, no band gap at the Fermi level and hence are conducting.
Metallic bonding is mostly non-polar, because even in alloys there is little difference among the electronegativities of the atoms participating in the bonding interaction (and, in pure elemental metals, none at all). Thus, metallic bonding is an extremely delocalized communal form of covalent bonding.
Such nobility is mainly associated with the relatively high electronegativity values of the noble metals, resulting in only weakly polar covalent bonding with oxygen. [3] The table lists the melting points of the oxides of the noble metals, and for some of those of the non-noble metals, for the elements in their most stable oxidation states.
Native copper is an uncombined form of copper that occurs as a natural mineral. Copper is one of the few metallic elements to occur in native form, although it most commonly occurs in oxidized states and mixed with other elements. Native copper was an important ore of copper in historic times and was used by pre-historic peoples.
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Cu 2 S can be prepared by treating copper with sulfur or H 2 S. [2] The rate depends on the particle size and temperature. [5] Cu 2 S reacts with oxygen to form SO 2: [6] 2 Cu 2 S + 3 O 2 → 2 Cu 2 O + 2 SO 2. The production of copper from chalcocite is a typical process in extracting the metal from ores.