Category: transition metal
Atomic number: 29
Colour: reddish orange
Melting point: 1,085°C (1,985°F)
Boiling point: 2,562°C (4,644°F)
First identified: ancient civilizations
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Category: transition metal Atomic number: 29 Colour: reddish orange Melting point: 1,085°C (1,985°F) Boiling point: 2,562°C (4,644°F) First identified: ancient civilizations |
Copper is a native metal: this means it can be found in its pure or alloyed form in nature. For this reason, it was one of the first metals to be used by people – we know it was in use about 10,000 years ago (copper jewellery has been found in Iraq from the period), was being smelted from sulphide ores about 7,000 years ago and was then moulded into shapes about 6,000 years ago. Crucially, it was also the first metal to be deliberately alloyed with another metal – when combined with tin it forms bronze. This discovery marks the point at which metal tools started to replace stone ones, in the Bronze Age, which began in about 3500 BC. Along with silver and gold, it has frequently been used to make coins, although copper coins have tended to be the lower-value denominations.
The chemical symbol Cu derives from Roman times – it was known as aes cyprius (metal of Cyprus, location of the largest copper mines of the period). This was gradually corrupted to cuprum in Latin and copper in English.
Copper has an unusual reddish colour and is a hardy metal – when archaeologists excavated the Great Pyramid of Giza, they found copper tubes, part of a plumbing system, that were still in usable condition. It is also often used in wiring – it conducts heat and electricity well and can be stretched out relatively easily – and in building (especially piping and roofing), as well as in decorative art – statues and other artefacts made of it become covered in a green verdigris (patina) as the metal oxidizes. Compounds of copper, especially copper salts, also give a green or blue colour to minerals such as azurite or turquoise, and it has historically been used to produce paint pigments in these colours.
The human body requires trace amounts of copper. However, a more interesting fact is that, while most fish and mammals have some kind of haemoglobin, an iron complex, arthropods and molluscs need copper for the same purpose – their blood contains the copper complex hemocyanin instead of haemoglobin.