Module
C2: Material choices
C2.1 How do we measure the properties
of materials and why are the results useful?
1. interpret information about how solid materials can differ with
respect to properties such as
melting point, strength (in tension or compression), stiffness,
hardness and density
2. relate properties to the uses of materials such as plastics,
rubbers and fibres
3. relate the effectiveness and durability of a product to the
materials used to make it
4. interpret information about the properties of materials such as
plastics, rubbers and fibres to
assess the
suitability of these materials for particular purposes.
C2.2 Why is crude oil important as a
source of new materials such as plastics and fibres?
1. recall that the materials we use are chemicals or mixtures of
chemicals, and include metals,
ceramics and polymers
2. recall that materials can be obtained or made from living things,
and give examples such as
cotton, paper, silk and wool
3. recall that there are synthetic materials that are alternatives to
materials from living things
4. recall that raw materials from the Earth’s crust can be used to
make synthetic materials
5. interpret representations of rearrangements of atoms during a
chemical reaction
6. understand that in a chemical reaction the numbers of atoms of each
element must be the
same in the products as in the reactants
7. recall that crude oil consists mainly of hydrocarbons, which are
chain molecules of varying
lengths made from carbon and hydrogen atoms only
8. recall that only a small percentage of crude oil is used for
chemical synthesis and that most is
used as fuels
9. understand that the petrochemical industry refines crude oil by
fractional distillation;
hydrocarbons are separated into fractions of different boiling points,
to produce fuels,
lubricants and the raw materials for chemical synthesis
10. relate the size of the forces between hydrocarbon molecules to the
size of the molecules
11. relate the strength of the forces between hydrocarbon molecules in
crude oil to the amount
of energy needed for them to break out of a liquid and form a gas, and
to the temperature at
which the liquid boils
12. understand that some small molecules called monomers can join
together to make very long
molecules called polymers, and that the process is called
polymerisation
13. recall two examples of materials that, because of their superior
properties, have replaced
materials used in
the past.
C2.3 Why does it help to know about
the molecular structure of materials such as plastics and fibres?
1. understand that it is possible to produce a wide range of different
polymers with properties that
make them each suited to a particular use
2. understand how the properties of polymers depend on how their
molecules are arranged and
held together
3. relate the strength of the forces between the molecules in a
polymer to the amount of energy
needed to separate them from each other, and therefore to the strength,
stiffness, hardness
and melting point of the solid
4. understand how modifications in polymers produce changes to their
properties (see C2.1), to
include modifications such as:
a. increased chain length
b. cross-linking
c. the use of plasticizers
d. increased crystallinity.
C2.4 What is
nanotechnology and why is it important?
1. recall that nanotechnology involves structures that are
about the same size as some
molecules
2. understand that nanotechnology is the use and control
of structures that are very small (1 to
100 nanometres in size)
3. understand that nanoparticles can occur naturally (for
example in seaspray), by accident (for
example as the smallest particulates from combustion of
fuels), and by design
4. understand that nanoparticles of a material show
different properties compared to larger
particles of the same material, and that one of the
reasons for this is the much larger surface
area of the nanoparticles compared to their volume
5. understand that nanoparticles can be used to modify the
properties of materials, and give
examples including:
a. the use of silver nanoparticles to give fibres
antibacterial properties
b. adding nanoparticles to plastics for sports equipment
to make them stronger
6. understand that some nanoparticles may have harmful
effects on health, and that there is
concern that products with nanoparticles are being
introduced before these effects have been
fully
investigated.
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