Copper properties and applications, Essays (high school) of Mathematics

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. 1 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.) 2 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 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. 5 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. Non-magnetic Copper is non-magnetic and non-sparking. Because of this, it is used in special tools and military applications. Attractive Colour Copper and its alloys, such as brass, are used for jewellery and ornaments. They have an attractive golden colour which varies with the copper content. They have a good resistance to tarnishing making them last a long a time. Recyclable Copper can be recycled without any loss of quality. Around 40% of Europe’s demand is met from recycled copper. For more information, see the Copper Recycling and Sustainability resource. Catalytic Copper can act as a catalyst – meaning a substance that can speed up a chemical reaction and improve its efficiency. It does so by reducing the activation energy. Catalysts in biological reactions are called enzymes. Copper speeds up the reaction between zinc and dilute sulfuric acid. It is found in some enzymes, one of which is involved in respiration. It really is a vital element! 6 Copper Development Association is a non-profit organisation that provides information on copper’s properties and applications, its essentiality for health, quality of life and its role in technology. It supports education through a collection of resources spanning biology, chemistry and physics. These materials have been developed in conjunction with the Association for Science Education, and reviewed by teachers. For more resources, visit www.copperalliance.org.uk/education. A pallet of recycled copper ready to be reused and helping to preserve natural resources.