Chemistry Paper 2 Topic 10 – Using Resources
Ceramics, Composites and Polymers
Ceramics are non-metal solids with high melting points that are not made from carbon-
based compounds.
Some ceramics are made from clay, which is a soft material when it is dug up from the
ground and, therefore, can be moulded into different shapes.
When it is fired at high temperatures, it hardens to form a clay ceramic; its ability to be
moulded when wet makes clay ideal for making pottery and bricks.
Another example of a ceramic is glass. Glass is generally transparent, can be moulded when
hot and can be brittle when thin.
Most glass made is soda-lime glass, which is made by heating a mixture of limestone, sand
and sodium carbonate (soda) until it melts. When the mixtures cools, is comes out as glass.
Borosilicate glass has a higher melting point than soda-lime glass; it is made in the same way
as soda-lime glass, using a mixture of sand and boron trioxide.
Composites are made of one material embedded in another. Fibres or fragments of a
material (reinforcements) are surrounded by a matrix acting as a binder.
Two important things can influence the properties of a polymer – how it is made and what it
is made from.
The monomers
that a polymer is made from determine the type of bonds that form between the polymer
chains. These weak bonds between the different molecule chains determine the properties
of the polymer:
Properties of Materials
Ceramics include glass and clay ceramics such as porcelain and bricks. They are insulators of
heat and electricity, brittle and stiff.
Polymers are also insulators of heat and electricity; they can be flexible and be easily
moulded. Thus, they have many applications including clothing and insulators in electrical
items.
The properties of composites depend on the matrix/binder and the reinforcement used to
make them, so they have many different uses.
, Chemistry Paper 2 Topic 10 – Using Resources
Metals are malleable, good conductors of heat and electricity, ductile (can be drawn into
thin wires), shiny and stiff. Metals have many uses, including electrical wires car bodywork
and cutlery.
Pure Metals are Too
Soft for Everyday Use:
Alloys are made by adding another element to the metal. This disrupts the regular
structure of the metal, making alloys harder than pure metals.
For example, alloys of iron called steels are often
used instead of pure iron. Steels are made by
adding small amounts of carbon and sometimes
other metals to iron.
More examples include:
Corrosion
Corrosion is where metals react with substances in their environment and are gradually
destroyed.
Iron corrodes easily i.e. it rusts (note – the term ‘rust’ is only used for the corrosion of iron).
In order to rust, iron needs to be in contact with both oxygen and water, which are present
in the air. The stuff we call rust is actually the compound hydrated iron (III) oxide.
Corrosion only happens on the
surface of a material, where it is exposed to the air.
Unfortunately, rust is a soft crumbly solid that soon flakes off to leave more iron
available to rust again. This means that, eventually, all the iron in an object corrodes
away even if it was not initially at the surface.
Aluminium also corrodes when exposed to air, though much less than iron and steel.
Unlike iron objects, things made from aluminium are not completely destroyed by corrosion.
This is because the aluminium oxide that forms when aluminium corrodes does not flake
away. In fact, it forms a protective layer that sticks firmly to the aluminium below and stops
any further reaction taking place.
Ceramics, Composites and Polymers
Ceramics are non-metal solids with high melting points that are not made from carbon-
based compounds.
Some ceramics are made from clay, which is a soft material when it is dug up from the
ground and, therefore, can be moulded into different shapes.
When it is fired at high temperatures, it hardens to form a clay ceramic; its ability to be
moulded when wet makes clay ideal for making pottery and bricks.
Another example of a ceramic is glass. Glass is generally transparent, can be moulded when
hot and can be brittle when thin.
Most glass made is soda-lime glass, which is made by heating a mixture of limestone, sand
and sodium carbonate (soda) until it melts. When the mixtures cools, is comes out as glass.
Borosilicate glass has a higher melting point than soda-lime glass; it is made in the same way
as soda-lime glass, using a mixture of sand and boron trioxide.
Composites are made of one material embedded in another. Fibres or fragments of a
material (reinforcements) are surrounded by a matrix acting as a binder.
Two important things can influence the properties of a polymer – how it is made and what it
is made from.
The monomers
that a polymer is made from determine the type of bonds that form between the polymer
chains. These weak bonds between the different molecule chains determine the properties
of the polymer:
Properties of Materials
Ceramics include glass and clay ceramics such as porcelain and bricks. They are insulators of
heat and electricity, brittle and stiff.
Polymers are also insulators of heat and electricity; they can be flexible and be easily
moulded. Thus, they have many applications including clothing and insulators in electrical
items.
The properties of composites depend on the matrix/binder and the reinforcement used to
make them, so they have many different uses.
, Chemistry Paper 2 Topic 10 – Using Resources
Metals are malleable, good conductors of heat and electricity, ductile (can be drawn into
thin wires), shiny and stiff. Metals have many uses, including electrical wires car bodywork
and cutlery.
Pure Metals are Too
Soft for Everyday Use:
Alloys are made by adding another element to the metal. This disrupts the regular
structure of the metal, making alloys harder than pure metals.
For example, alloys of iron called steels are often
used instead of pure iron. Steels are made by
adding small amounts of carbon and sometimes
other metals to iron.
More examples include:
Corrosion
Corrosion is where metals react with substances in their environment and are gradually
destroyed.
Iron corrodes easily i.e. it rusts (note – the term ‘rust’ is only used for the corrosion of iron).
In order to rust, iron needs to be in contact with both oxygen and water, which are present
in the air. The stuff we call rust is actually the compound hydrated iron (III) oxide.
Corrosion only happens on the
surface of a material, where it is exposed to the air.
Unfortunately, rust is a soft crumbly solid that soon flakes off to leave more iron
available to rust again. This means that, eventually, all the iron in an object corrodes
away even if it was not initially at the surface.
Aluminium also corrodes when exposed to air, though much less than iron and steel.
Unlike iron objects, things made from aluminium are not completely destroyed by corrosion.
This is because the aluminium oxide that forms when aluminium corrodes does not flake
away. In fact, it forms a protective layer that sticks firmly to the aluminium below and stops
any further reaction taking place.
