Copper is used in the automotive, building and telecommunications industries. Historically, the Americas have been the largest producers of copper in the world, but it is also mined in other regions, such as Australia and parts of Africa. Copper is most extensively used in establishing electrical current through copper wires; many of the metal's physical and chemical properties render it ideal for such an application. Properties of electrical wires are derived from their core component, which is copper.
Copper is a metal with a distinct reddish or orange tint, with a metallic lustre. The cubic crystalline structure is face-centred, and reflects only red and orange coloured light from the visible spectrum, giving it the familiar reddish hue. Compared to adjacent metals in the periodic table, copper is harder than zinc but softer than iron. The metal is malleable, meaning that it can be elongated with pressure and moulded into different shapes. Copper is also ductile, which enables it to change form and be stretched into long thin structures without breaking. These properties, along with its ability to conduct electricity extremely well, make copper suitable for use in electrical cable manufacturing, where these physical attributes are particularly desirable.
The atomic number of copper used in wires is 29, meaning it has 29 protons. Copper's symbol is "Cu," and its atomic weight is 63.54. Copper is placed in column 1B in the periodic table, along with silver and gold, whose symbols are "Ag" and "Au," respectively. Copper has a Moh's hardness (a system of measurement to evaluate the hardness of metals) of between 2.5 and 3. Copper used in manufacturing wires has a very high specific gravity of 8.2, which is much higher than other substances of industrial interest, such as water (1.0), carbon (2.2) and sulphur (2.1). The specific densities of silver and gold are both higher than copper, at 10.5 and 19, respectively. Copper wires have low chemical reactivity; in reaction with other elements, laboratory copper has a charge of +1, known as cuprous or +2, known as cupric.
Copper in electrical wires is resistant to corrosion. When exposed to damp air, the substance changes colour from reddish orange to reddish brown. In time, a fine greenish film, known as patina, coats the surface of the metal, protecting it from degradation through corrosion.
Copper in electrical wires has a melting point of 583 degrees C Centigrade (1083 degrees Celsius). Its density, measured in pound per cubic inches, is 0.323, and its tensile strength is 35. Copper's thermal conductivity (measured at 20 degrees Celsius) is 224, and its electrical conductivity is 10.37. Copper's linear coefficient of expansion is 9.4.