Metals are used in many everyday objects.
This morning when I woke up I decided to have a soft-boiled egg and a cup of
coffee.
The pot I used is made of metal. The
kettle is made of plastic, but the coiled
heating element inside it is made of
metal. Metals are good conductors of heat.
This is the reason why metals are used to make these everyday objects.
You would never see a pot made of wood or heating element made of plastic.
Metals are also good conductors of
electricity.
The wire connecting your kettle to the
electrical socket is actually made of
many copper wires, insulated with a layer of rubber. Think about the shapes of the
everyday objects we described. The pot, the heating element inside the kettle,
and the copper wires. Notice that they
are very different. Metals are malleable.
This means that they can be moulded into different shapes. Metals are very ductile.
This means that they can be stretched
into wires. To fully understand these
properties of metals we must understand metallic bonding.
When we talk about metallic bonding we are actually describing the
electrostatic attraction between the
metal ions, arranged in a lattice
structure and the free-floating
electrons around them.
Since these electrons are free to move
around, the term sea of electrons is also
used.
What is a lattice structure, and where
have you heard this term before?
Pause the lesson to think about
this and resume when you are done.
The term 'lattice structure' means that
there is a regular repeating pattern. We
have heard this term before when
discussing ionic lattices. It is used
to describe the alternating positions of the metal and nonmetal ions. In metallic
structures however there are only metal ions. These metal ions are arranged
side-by-side in a regular repeating
pattern. The free-floating electrons act
like a glue and hold the structure in
place.
This is a very strong attraction and
explains why metals have high melting
and boiling points.
A lot of heat energy is needed to
overcome this attraction.
This is also why metals are very good
conductors of heat. Free-floating
electrons are the reason why metals can conduct electricity.
Metals are malleable and ductile because no matter what shape the metal takes, the
free-floating electrons will conform to
that shape. The strong electrostatic
attraction will remain and therefore the structure stays intact.
Let's think about it: cars, bicycles
trains, planes, buildings, cutlery,
spectacles, furniture and endless items can be made for metals. To recap the
electrostatic attraction between metal
ions arranged in the lattice structure
and free-floating electrons is known as metallic bonding.
This explains many properties of metals: they are good conductors of heat and
electricity, have high melting and
boiling points, and are malleable and
ductile.
