Copper is an excellent electrical conductor. Most of its uses are based on
this property or the fact that it is also a good thermal conductor. However,
many of its applications also rely on one or more of its other properties. For
example, it wouldn't make very good water and gas pipes if it were highly reactive.
On this page, we look at these other properties:
a good electrical conductor
a good thermal conductor
easy to alloy
Copper is low in the reactivity series. This means that it doesn't tend to corrode.
Again, this is important for its use for pipes, electrical cables, saucepans
However, 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.
Copper is a naturally hygienic metal that slows down the growth of germs such
as E-coli (the “burger bug”), MRSA (the hospital “superbug”)
This is important for applications such as food preparation, hospitals, coins
(see biocidal copper), door knobs and plumbing systems.
Copper can be joined easily by soldering or brazing. This is useful for pipework
and for making sealed copper vessels.
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.
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 is non magnetic and non sparking. Because of this, it is used in special
tools and military applications.
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.
Copper can be combined with other metals to make alloys. The most well known
are brass and bronze. Although copper has excellent electrical and thermal properties,
it needs to be hardened and strengthened for many industrial applications. It
is therefore mixed with other metals and melted. The liquid metals form a solution
which, when they solidify, are called alloys. Some copper alloys are:
brass: copper + zinc
bronze: copper + tin
cupro nickel: copper + 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.
In ancient times, the first alloys could be made in the temperatures of a camp
fire. This led to the Bronze Age.
Copper can be recycled without any loss of quality. 40% of the world's demand
is met by recycled copper (see extracting copper).
Copper can act as a catalyst. For example, it speeds up the reaction between
zinc and dilute sulphuric acid. It is found in some enzymes, one of which is
involved in respiration. So it really is a vital element.