Download Copper properties and applications and more Essays (high school) Mathematics in PDF only on Docsity!
The word copper comes from the Latin word ‘cuprum’, which means ‘ore of Cyprus’. This is why the chemical symbol for copper is Cu. Copper has many extremely useful properties, including:
- good electrical conductivity
- good thermal conductivity
- corrosion resistance It is also:
- easy to alloy
- antimicrobial
- easily joined
- ductile
- tough
- non-magnetic
- attractive
- recyclable
- catalytic See below for more information on each of these properties, and how they benefit us in our daily lives.
Good Electrical Conductivity
Copper has the best electrical conductivity of any metal, except silver. A good electrical conductivity is the same as a small electrical resistance. An electric current will flow through all metals, however they still have some resistance, meaning the current needs to be pushed (by a battery) in order to keep flowing. The bigger the resistance, the harder we have to push (and the smaller the current is). Current flows easily through copper thanks to its small electrical resistance, without much loss of energy. This is why copper wires are used in mains cables in houses and underground (although overhead cables tend be aluminium because it is less dense). However, where size rather than weight is important, copper is the best choice. Thick copper strip is used for lightning conductors on tall buildings like church spires. The copper strip has to be thick so that it can carry a large current without melting.
11 - 14 YEARS
14 - 16 YEARS
Copper: Properties
and Applications
Copper is a metal with symbol Cu, atomic number 29 and atomic mass 63.55. An electrical circuit board benefiting from copper’s good electrical conductivity.
GENERAL
Figure 1: A copper wire is made of a lattice of copper ions. There are free electrons that move through this lattice like a gas
CLICK HERE TO SEE ANIMATED
VERSIONS OF THESE DIAGRAMS
Copper wire can be wound into a coil. The coil will produce a magnetic field and, being made of copper, won’t waste much electrical energy. Copper coils can be found in: How copper conducts Copper is a metal made up of copper atoms closely packed together. If we could look closely enough, we would see that there are electrons moving about between the copper atoms. Each copper atom has lost one electron and become a positive ion. So copper is a lattice of positive copper ions with free electrons moving between them. (The electrons are a bit like the particles of a gas that is free to move within the surfaces of the wire). The electrons can move freely through the metal. For this reason, they are known as free electrons. They are also known as conduction electrons, because they help copper to be a good conductor of heat and electricity. The copper ions are vibrating (Click on the link to the animated version above Figure 1). Notice that they vibrate around the same place whereas the electrons can move through the lattice. This is very important when we connect the wire to a battery. Conducting electricity We can connect a copper wire to a battery and a switch. Normally, the free electrons move about randomly in the metal. When we close the switch, an electric current flows. Now the free electrons flow through the wire (Figure 2) they are moving Device Use Motors Locks, scrapyard cranes, electric bells. (see Electromagnets) Pumps, domestic appliances (washing machines, dishwashers, fridges, vacuum cleaners), cars (starter motors, windscreen wipers, electric windows), computers (disc drives, fans), entertainment systems (DVD players). (See Electric Motors.) Dynamos Bicycles, power stations Transformers Mains adaptors, electricity substations, power stations. (See Copper and Electricity: Transformers.) Figure 2: Operating the switch in the circuit (above left) causes electrons to flow from left to right, in the opposite direction of the current. FLOW OF ELECTRONS CURRENT
Conducting heat
Copper is made from a lattice of ions with free electrons (see Figure 1). The ions are vibrating and the electrons can move through the copper (rather like a gas). Figure 3 shows what happens when one end of the piece of copper gets hotter. The copper ions at the hot end vibrate more. Note: the electrons have been left out of the picture to keep it clear. Figure 4 focuses on just a few electrons to see how they conduct heat from the left to the right.
- A free electron collides with an ion at the hot end, and gains kinetic energy (it speeds up).
- It moves to the cold end.
- It collides with a ‘cold ion’, making the previously cold ion vibrate more. This heats up the cold end.
- In this way, energy is transferred through copper, from hot to cold. Non-metals conducting heat Compare this with how heat is conducted in a non-metal. The vibrating particles pass on the vibrations to their nearest neighbours. This is much slower. That’s why metals are the best conductors - their free electrons can carry the energy along their length.
Corrosion Resistance
Copper is low in the reactivity series. This means that it doesn’t tend to corrode. This is important for its use for pipes, electrical cables, saucepans and radiators. It also means that it is well suited to decorative use. Jewellery, statues and parts of buildings can be made from copper, brass or bronze and remain attractive for thousands of years. For more information on the benefits of copper’s corrosion resistance for marine applications, see the Copper Alloys in Aquaculture resource.
Alloys Easily Joined
Copper can be combined easily with other metals to make alloys. The first alloy produced was copper melted with tin to The copper alloy tree shows the options for adding other metals to make different alloys. Below are some examples. Click here see a larger version of the diagram. Copper + tin = tin bronze Copper + tin + phosphorus = phosphor bronze Copper + aluminium = aluminium bronze Copper + zinc = brass Copper + tin + zinc = gunmetal Copper + nickel = copper-nickel Copper + nickel + zinc = nickel silver.
form bronze - a discovery so important that periods in history are called The Bronze Age. Much later came brass (copper and zinc), and - in the modern age - cupronickel (copper and nickel). The alloys are harder, stronger and tougher than pure copper. They can be made even harder by hammering them - a process called ‘work hardening’. For more information, see the Copper in Coinage resource. You can also view the Copper Development Association pages on Copper and its Alloys.
Antimicrobial
Copper is inherently antimicrobial, meaning it will rapidly kill bacteria, viruses and fungi that settle on its surface. This property is leading to the installation of surfaces made from copper and copper alloys in hospitals and other areas where hygiene is a key concern. For more information, see the Copper, Pathogens and Disease resource.
Easily Joined
Copper can be joined easily by soldering or brazing. This is useful for pipework and for making sealed copper vessels.
Ductile
Copper is a ductile metal. This means that it can easily be shaped into pipes and drawn into wires. Copper pipes are lightweight because they can have thin walls. They don’t corrode and they can be bent to fit around corners. The pipes can be joined by soldering and they are safe in fires because they don’t burn or support combustion.
Tough
Copper and copper alloys are tough. This means that they were well suited to being used for tools and weapons. Imagine the joy of ancient man when he discovered that his carefully formed arrowheads no longer shattered on impact. The property of toughness is vital for copper and copper alloys in the modern world. They do not shatter when they are dropped or become brittle when cooled below 0°C. Copper’s inherent antimicrobial properties make it a good choice for the surfaces that staff, patients and visitors touch in hospitals, helping to prevent the spread of infection. A tuba made from brass.
