Copper (symbol Cu), known for thousands of years, about 5,000 ago led man out of the Stone Age and into the Bronze Age. When combined with up to 25% tin copper forms the alloy bronze. Another early copper containing alloy, made at least 2,500 years ago, is brass, which contains copper alloyed to 5 – 45% zinc. Archaeological evidence of man’s use of the element dates back 11,000 years but until alloyed with tin copper was too soft for use in tool manufacture.
Copper’s name and symbol comes from the Latin word “cuprum” meaning “from the island of Cyprus”. It was from this island that the Roman Empire obtained much of its supply of the metal.
With its long industrial history copper still plays an important part in our every day lives. As it is second only to silver in its ability to conduct electricity, copper wire provides a valuable resource to the electrical industry. This malleable and ductile metal is also of use in the manufacture of piping used in the water supply industry. In addition to being a good electrical conductor, copper is an efficient conductor of heat.
This reddish colored metallic element has the atomic number 29 placing it in period 4, group 11 (coinage metal group) of the periodic table. Its atomic weight is 63.546 and its ionization energy is 7.726 eV. The density of copper is 8.933 grams per cubic centimeter. It will melt at 1084.62° (C 1357.77 K, 1984.32°F) and boil at 2562°C (2835 K, 4644°F). Copper has two oxidation states, +1 and +2. Copper (I) salts are referred to as cuprous and copper (II) salts as cupric. Cupric oxide or copper (II) oxide (CuO) is a black compound while cuprous oxide or copper (I) oxide (Cu2O) is a red compound.
While deposits of native copper do exist, most of the world’s supply of the metal comes from the mineral ores cuprite, tenorite, malachite, chalcocite covellite and bornite. Natural copper has two stable isotopes copper-63 and copper-65. The estimated abundance of copper in the Earth’s crust is 60 milligrams per kilogram
Copper is an essential element for life but the quantity required is very small. The human body contains 1000 parts per billion by weight. The element plays an essential part in biological redox enzymes and haemacyanin (the substance that gives the octopus its blue colored blood). However, many copper compounds are toxic, 30 grams of copper sulphate (often used as an algaecide in aquariums) can form a lethal dose if ingested.
Reference sources:
Los Alamos National Laboratory Chemistry Division
Web Elements
Jefferson Laboratories Science Education website
