From being the first metal to be manipulated by humans to becoming an important metal in the industry today, copper has proved to be one of the most ‘in-demand’ elements. It is the metal that serves mankind with its varied applications – right from making ornaments to weapons and from conducting electricity to proving its worth as anti-bacterial.
In this article, our special correspondent explains that there is more to copper than just being a shiny element !
Copper, the shiny reddish element, was the first metal to be worked upon and crafted by humans. It has played an important role in the history of mankind from around the end of the Stone Age till the present-day Information Age. Today, it is ranked third among the most consumed industrial metals in the world, after iron and aluminium.
When they think of copper, most people would probably visualise coins, kitchen utensils, electrical wiring or even the Statue of Liberty, one of the most famous international landmarks and the biggest copper-clad statue in the world. With hundreds of copper sheets covering its outer surface, the iconic statue was originally a shiny, reddish brown in colour, reflecting the natural colour of copper. Over the years it acquired the blue-green colour we see today. That’s because copper tends to change colour after long periods of exposure. It first reacts with oxygen in the air to form oxides, and then these react with carbon dioxide and sulphur to form copper carbonate, copper sulphide, and copper sulphate. It is these compounds that form the outer, protective blue-green patina that actually preserves the underlying copper from corrosion.
We may not always be aware of it, but we interact with copper in numerous ways every day. In fact, it is one of the elements we depend on the most. From switching on electrical gadgets in our homes and offices and watching TV, to handling coins, cooking our food, or making calls from our mobile phones, during each of these and many other daily activities we use copper. In many countries, like the US and UK, not just electric wires, but almost all the pipes and tubing for potable water too are made from copper.
History down the ages
A key reason for the early discovery and significant use of copper in ancient times was that being slow to react with other substances, the metal occurred naturally in fairly notable amounts in the pure form. Ancient civilisations first used copper to make ornaments, tools, and coins. Many of these objects, some dating to as far back as 8000 BC, have been discovered.
One of the disadvantages of the metal was that it was too soft to be used for making weapons and tools. Then, around 3500 BC, the Mesopotamians discovered that copper when mixed with tin forms a much harder substance—bronze. This technological advance led to the end of the Copper or Chalcolithic Age and the beginning of the Bronze Age. The new alloy was not only harder but could also be forged and shaped through hammering or melted and poured into hollow moulds to prepare castings of different shapes.
The Romans used copper and bronze for making plumbing tubings and fittings, armours, helmets, weapons like swords and spears, ornaments, decorative items, and parts of musical instruments. The Egyptians used copper for making water pipes around the same time as the Romans. They also used copper and bronze for making mirrors, razors, adornments and weights and balances. Coins made out of copper were used by the Romans, Greeks, Chinese and other civilisations.
Brass, an alloy of copper and zinc, was discovered around 1400 BC, but its use was limited. The Romans used it for making coins and golden coloured helmets and ornaments. Brass began to be used extensively from around the 18th century after a method for extracting pure zinc was found.
Properties
The chemical symbol for copper, Cu, was derived from the Latin name for the metal—cuprum—which itself originated from the Latin phrase Cyprium aes, meaning ‘metal from Cyprus’. Ancient Romans got most of their supply of copper from Cyprus.
An interesting feature about copper is that apart from gold, it is the only metal that doesn’t have a natural silverish or grey colour, but a shiny, reddish hue.
Being ductile, it can be stretched into wires and can be easily machined, fabricated or cast into any desired shape. Only silver has higher thermal and electrical conductivity than copper. But given how costly silver is, for all practical purposes, copper is the most cost-effective electrical conductor in the periodical table.
Though somewhat unreactive, copper can form alloys that are harder than itself or the metals it combines with. When it combines chemically with the atoms of other elements, it forms various industrially useful compounds that are either cuprous (copper I: copper ions having a charge of +1) or cupric (copper II: copper ions having a charge of +2), the cupric compounds being generally more stable.
Civilisation’s most practical metal
Copper has proved to be an exceptionally useful metal throughout history. One of the reasons for its continued and widespread use is that it can be recycled economically and indefinitely, that too without losing any of its physical or chemical properties.
The main uses of copper are in building construction and the manufacture of electrical and electronic equipment. Around three-fourths of the copper produced is used for power transmission and generation, building wiring, electrical and electronic products, and telecommunications. Copper is also used for making copper-bottom cooking utensils since it heats uniformly.
Till today, many countries, like the UK, US, and even India, use copper and its alloys for coinage. In the new Indian ten-rupee coins, copper is the main metal. Similarly, the 10, 20, and 50 Euro coins are 89% copper. Till around three decades ago, the one-cent American coins were 98% copper. At present, they are made out of copper-plated pure zinc.
Incidentally, till some decades ago, the buttons and badges on the uniforms of police officers in the US and UK were made from copper. While according to a popular myth, this was the origin of the slang term for policemen—’coppers’, later shortened to ‘cops’—language experts say the nickname probably came from the old English word ‘cop’ which meant ‘to capture’.
In modern times, copper is playing a key role in electric and hybrid vehicles. According to some experts in this field, the copper content of future vehicles could be triple that of today’s content.
Copper’s anti-microbial properties have further broadened its use. It was once used to coat the bottoms of ships because of its property of inhibiting the growth of bacteria, barnacles, and other life forms. Today, it is woven into fabrics used for making anti-microbial products such as socks for fighting foot fungus, and is also used in the medical field. For instance,hospitals are using it to cover frequently-touched surfaces such as door handles, bed rails, and call buttons to check the spread of hospital-acquired infections.
Copper alloys too have multiple uses in the electrical field and for making industrial machinery.
Some decades ago, copper bracelets were being popularised as cures for arthritis. In 2013, a controlled, double-blind scientific study in the UK concluded that these had no meaningful therapeutic effects.
The two most industrially important copper compounds are: 1) Cupric sulphate (CuSO4) used mainly for agricultural purposes as a pesticide, germicide, feed additive, and soil additive, and in medicine as a fungicide, bactericide, and astringent; and 2) Cupric chloride (CuCl2) used as a wood preservative, mordant in the printing and dyeing industries, pigment for glass and ceramics, and as a disinfectant.
Currently, scientists are researching the use of copper for producing futuristic electronic paper, wearable biosensors, and other ‘soft’ electronics.
Essential micronutrient
Copper, which is present in every tissue of our body, helps it to utilise iron properly, helps the thyroid gland to function normally, keeps bones healthy, preserves the myelin sheath protecting our nerves, and is crucial for catalysing the formation of haemoglobin. Being a vital micronutrient, we need to include it in our diet.
Foods like beans, grains, potatoes, leafy vegetables, and asparagus are good sources of copper.
2019 – Will King Copper continue to reign supreme?
Since the last few decades, the demand for copper has been rapidly increasing due to many developing countries, especially China and India, getting more industrialised. The rising demand has led to the price of copper increasing four-fold in recent times, and predictions of ‘King Copper’ strengthening its in-demand position even further this year.
In the meanwhile, the applications of copper keep growing as new aspects of its usefulness in industries varying from pharmaceuticals to electronics keep on being discovered.
References
- Stephanie Pappas: Facts About Copper – LiveScience, 12 September, 2018, https://www.livescience.com/29377-copper.html
- Chris Woodford: Copper – ExplainThatStuff.com, 4 September, 2019, https://www.explainthatstuff.com/copper.html
- C. Claiborne Ray: A Scientific Lens on Copper – The New York Times, 23 January, 2017, https://www.nytimes.com/2017/01/23/science/copper-bracelets-arthritis.html
- Jean-Marc Böhlen: Copper Compendium, Part 2: Copper is Key in the Modern Age – Accelerating Science, 14 July, 2015, https://www.thermofisher.com/blog/metals/copper-compendium-part-2-copper-is-key-in-the-modern-age/
- Accelerating Science: 8 Fun Facts About Copper – ThermoFisher.com, https://www.thermofisher.com/content/dam/tfs/ATG/CAD/CAD%20Marketing%20Material/CAD%20Marketing%20Images/Infographics/Infographic-Copper.pdf
- Vin Calcutt: Introduction to Copper: Applications – Innovations, August 2001, https://www.copper.org/publications/newsletters/innovations/2001/08/intro_to_copper.html
- Terence Bell: The Ancient History of Copper – TheBalance.com, 30 December, 2018, https://www.thebalance.com/copper-history-pt-i-2340112
- Steve Mylon: Copper – Chemistry World, 30 December, 2009, https://www.chemistryworld.com/podcasts/copper/3005744.article
- Frank Holmes: Will 2019 Be The Year Of King Copper? – Forbes.com, 19 February, 2019, https://www.forbes.com/sites/greatspeculations/2019/02/19/will-2019-be-the-year-of-king-copper/#3930821e2ba3
