C4 - Material Choices Flashcards
What is a polymer?
A large molecule formed from smaller
molecules called monomers.
What is meant by the term brittle?
Easily broken
What is meant by the terms tension and
compression?
● Tension - pulling
● Compression - squashing
When can a material conduct electricity?
When it contains charged particles which
are free to move.
What is meant by the term ductile?
Ability of a material to be drawn into
wires.
What is meant by the term malleable?
If a material is malleable it can be
pressed into shape without breaking or
returning to the original shape.
What are the general properties of glass
ceramics?
- Transparent
- Strong but brittle
- Easily moulded into shapes
- Poor conductors
What are the general properties of clay
ceramics?
- Opaque
- Soft and malleable
- Hardened with heat
- Brittle once hardened
- Poor conductors
What are the general properties of
polymers?
- Properties can be adapted to suit the purpose. - Usually tough and flexible. - Can be transparent or opaque. - Poor conductors.
What are the general properties of
metals?
- Shiny
- Malleable
- Ductile
- Good conductors
- Can form alloys to produce more desirable
properties
What is a composite material?
Contains two or more materials with different
properties.
Typically, there are two components: the
reinforcement (makes up the bulk of the material)
and the matrix (binds the reinforcement together).
Why do composite materials have a wide
range of different properties?
As composite materials are made of several
materials, the properties can be tailored to suit
the need of the composite. Different composite
materials contain different reinforcements and
matrixes so the properties vary.
What should be used to construct large
buildings: reinforced concrete or
fibreglass? Why?
Reinforced concrete because it is strong
in compression and tension and slightly
flexible.
What should be used to make tennis
rackets: timber or fibre reinforced
plastic? Why?
Fibre reinforced plastic because it has a
low density so is lightweight and is
flexible and strong in tension.
What is an alloy?
A mixture of a metal and one or more
other elements.
How do the properties of alloys differ to
the properties of metals?
Alloys are harder and less malleable. This is
because the uniform rows of atoms in metals
are distorted by different sized atoms and so
the layers are unable to slide over one
another.
How do the uses of alloys differ to the
uses of metals?
Alloys are harder so they are often used
rather than metals as they have more
desirable properties.
What is steel?
Steel is an alloy of iron.
Three main categories:
- Mild low carbon steel
- High carbon steel
- Stainless steel
How are the properties of mild steel
linked to its uses?
Mild steel is malleable and ductile so can
easily be pressed into shape to make car
parts. Galvanising and painting mild steel
makes it resistant to rust.
How are the properties of high carbon
steel linked to its uses?
High carbon steel is hard and resistant to
high temperatures so isn’t damaged
when using it as a drill bit.
How are the properties of stainless steel
linked to its uses?
Stainless steel is corrosion resistant so it
is suitable for use as cutlery.
What is magnalium?
What is it used for?
Magnalium is an alloy of magnesium and
aluminium.
It is lighter and stronger than aluminium and
more resistant to corrosion. It is used for car and
aircrafts.
What is brass?
What is it used for?
Brass is an alloy of copper and zinc.
Brass is hard and resistant to corrosion.
It is used for decorative hardware such
as plumbing fittings.
What is addition polymerisation?
Addition polymerisation involves the
removal of the C=C double bond from an
alkene to produce a polymer.
What is a repeat unit?
A section of the polymer which is
repeated throughout the whole polymer
structure.
Many ethene molecules are joined
together. What is the name of the
polymer that forms?
Poly(ethene)
What is condensation polymerisation?
Formation of a polymer with the release
of a small molecule such as water.
Compare condensation polymerisation
and addition polymerisation
Condensation polymerisation |Addition polymerisation
Needs 2 types of monomer | Only 1 type of monomer
Monomers need two functional groups minimum | Monomers must have C=C bond
Forms 2 products (polymer and many small molecules) | Only forms the polymer
What is an ester?
A molecule formed during a condensation
reaction between an alcohol and a
carboxylic acid. One water molecule also
forms during this reaction.
How is a polyester formed?
Formed from a condensation reaction
between a dicarboxylic acid (contains 2
COOH groups) and a diol (contains 2 OH
groups).
How many monomers are in one repeat
unit of a polyester?
Two
What is a polyamide formed from?
Formed from a condensation reaction
between a diamine (contains 2 NH_2
groups) and a dicarboxylic acid (contains
2 COOH groups).
Give a biological example of a polymer
DNA
How many different monomers make up
DNA?
Four
What are the monomers in DNA called?
Nucleotides
Name two more natural polymers and
give their monomers
- Cellulose and starch (monomer is glucose)
- Proteins (monomer is amino acids)
Do the atoms that make up a material
have the same properties as the bulk
material?
No
Which three things affect the properties
of a material?
- Types of bonds.
- Strength of bonds in comparison to
intermolecular forces. - Arrangement of atoms.
Two materials are made from carbon.
Will these materials have the same
properties?
No.
- They may have different bonds that
have different bond strengths. - The atoms may be arranged differently.
What are intermolecular forces?
(Relatively weak) forces of attraction
between molecules.
What bonds does carbon form? How
many of these bonds can carbon form?
Carbon forms four covalent bonds.
What is an organic compound?
A compound containing carbon atoms
covalently bonded together.
Why are there a large number of
different organic compounds?
Because carbon can form homologous
series of similar compounds, chains and
rings.
What bonds are found in polymers?
Strong covalent bonds.
Why do polymers generally have a
higher melting point than other organic
molecules?
Polymers are long chained molecules.
Longer chains mean there are more
intermolecular forces between molecules and
so more energy is required to melt polymers.
What properties of polymers are affected
by intermolecular forces?
- Melting point
- Behaviour on heating
- Hardness
- Flexibility
How are bonds arranged in giant
covalent structures?
Many atoms covalently bonded together
in a three-dimensional arrangement.
What are allotropes? Give an example
Different forms of the same element in
the same state.
E.g. allotropes of carbon are graphite
and diamond.
Describe the structure and bonding of
diamond
- Giant covalent structure.
- Each carbon atom is covalently bonded to
four other carbon atoms. - Regular tetrahedral structure.
- No free electrons.
What are the properties of diamond?
Explain these properties
- Hard due to the 3D structure held by covalent bonds.
- High melting point because strong covalent bonds
require a lot of energy to break. - Doesn’t conduct electricity as there are no charge
particles that can move.
Describe the structure and bonding of
graphite
- Giant covalent structure.
- Each carbon atom is covalently bonded to three other
carbon atoms. - Hexagonal layers.
- Weak attractive forces between layers.
- There is one delocalised electron per carbon bond.
What are the properties of graphite?
Explain these properties
- Electrical conductor because delocalised electrons are free
to move and carry charge. - Soft and slippery (can be used as lubricant) because the
force between layers are weak so the layers can slide over
each other. - High melting point because strong covalent bonds require a
lot of energy to break.
Describe the bonding in ionic
compounds
- Giant ionic lattice.
- Oppositely charged ions alternate in a
regular 3D structure. - Electrostatic attraction between the
oppositely charged ions.
Describe and explain the properties of
ionic compounds
- High melting point due to strong ionic bonds
requiring a large amount of energy to break. - Conduct electricity when molten or aqueous
as the ions are free to move and carry charge.
Describe the bonding in metals
- 3D arrangement of layers positive metal
ions held in a sea of delocalised negative
electrons. - Metallic bonding (electrostatic attraction
between cations and electrons).
Describe and explain the properties of
metals
- High melting point, strong and hard due to strong
metallic bonds. - Malleable and ductile because layers of ions can
slide across each other. - Good conductors because electrons are free to
move.
Describe the bonding of simple
molecular compounds
- Strong covalent bonds between
atoms. - Weak intermolecular forces of
attraction between small molecules.
Describe and explain the properties of
simple molecules
- Low boiling points due to weak intermolecular forces.
- Liquid or gaseous at room temperature due to low
melting and boiling points. - Don’t conduct electricity as there are no charged
particles.
Describe the bonding in giant covalent
structures
Many strong covalent bonds.
Describe and explain the properties of
giant covalent structures
- High melting points due to many strong
covalent bonds. - Most do not conduct due to no charged
particles being present (except graphite).
What units are used to compare the
sizes of nanoparticles, atoms and
molecules?
Nanometers (nm)
What is a nanoparticle?
A small structure that is 1-100
nanometers in size.
How large are nanoparticles in
comparison to atoms and simple
molecules?
Nanoparticles are larger than atoms and
simple molecules.
How does the size of nanoparticles affect
their properties and uses?
Nanoparticles are tiny so can enter
biological tissues. They can also be used
to form composite materials that have
more beneficial properties.
Why would nanoparticles be useful
catalysts?
Nanoparticles have a very high surface
area to volume ratio.
What is the equation to calculate the
surface area to volume ratio?
Surface area to volume ratio = Surface area ÷ Volume
Why might nanotubes be used to make
electrical circuits for computers?
- Can conduct electricity.
- Are very small so take up little space.
- Lightweight.
Why might nanoparticles be used in
sunscreen?
Some nanoparticles block UV light.
Nanoparticles absorb easily into the
body so won’t leave white marks on skin.
How does the arrangement of atoms in a
tube affect the properties and uses of
nanoparticles?
Only 1 atom thick, high tensile strength
and can conduct electricity and heat.
Can be used as molecular sieves or to
form composite materials.
What is a fullerene?
A fullerene is a molecule made of
carbon, shaped like a closed tube or
hollow ball.
Name two fullerenes
Graphene
C_60 (buckminsterfullerene)
What are the properties of the fullerene
C_60?
- Slippery due to weak intermolecular forces
- Low melting point
- Spherical
- Strong covalent bonds between carbon atoms
in a molecule - Large surface area
What are the properties of graphene?
- High melting point due to covalent
bonding between carbon atoms. - Conducts electricity because it has
delocalised electrons.
Why is graphene useful in electronics?
It is extremely strong and has delocalised
electrons which are free to move and carry
charge.
It is only one atom thick as it is a single layer of
graphite.
What are some of the risks associated
with nanoparticulate materials?
- Little is known about the effects of nanoparticles.
- May be harmful to health (they could enter the
bloodstream or be breathed in). - May catalyse harmful reactions inside the body.
- Large surface area to volume ratio may allow toxic
substances to bind to them and enter the body.
What is nanotechnology?
The use and control of structures that
are 1-100 nm in size.
Calculate the surface area to volume
ratio of a cube with side lengths of 8 nm
Surface area of each face = 8 x 8 = 64 nm
6 faces so total surface area = 6 x 64 = 384 nm^2
Volume = 8 x 8 x 8 = 512 nm3
Surface area to volume ratio = 384 ÷ 512 = 0.75
Explain oxidation and reduction in terms
of oxygen
Reduction is loss of oxygen.
Oxidation is gain of oxygen.
When a metal reacts with oxygen, does
reduction or oxidation take place?
Oxidation
The metal gains oxygen so is oxidised.
What causes corrosion?
Oxygen (in air) and water
Describe the process of corrosion
Reaction of metal with oxygen in the air
to form metal oxide.
What is rusting? Write a word equation
for the reaction
A reaction between iron or steel with
oxygen and water
Iron + oxygen + water → hydrated iron(III) oxide
State two ways corrosion can be
prevented
Physical barrier to water and oxygen
Sacrificial protection
How can a physical barrier to water and
oxygen be created to prevent corrosion?
Coat with plastic
Coat with paint
Coat with oil and grease
How can corrosion be prevented by
sacrificial protection?
Coat the metal being protected in a more
reactive metal. The more reactive metal
will be oxidised first.
What is galvanization?
A specific form of sacrificial protection
where iron is coated in zinc.
Explain reduction and oxidation in terms
of electrons
● Reduction is gain of electrons
● Oxidation is loss of electrons
What are the main stages included in a
life-cycle assessment?
- Processing raw materials
- Manufacture and packaging
- Transport
- Use
- Disposal
What factors are considered at each
stage of a life-cycle assessment?
- Use of water and other raw materials
- Energy use
- Environmental impact
- Waste
How does obtaining raw materials impact
the environment?
- Uses up limited resources.
- May damage habitats (mining and
felling trees). - Extraction often requires energy.
How does manufacture impact the
environment?
- Land required for factories.
- Releases pollution into rivers and the
atmosphere.
How does transport of products impact
the environment?
- Requires energy
- Releases pollution into the
atmosphere
How can a product be disposed?
- Landfill
- Incineration
- Recycled
How does disposal impact the
environment?
- Land used up for landfill sites.
- Pollution released during incineration.
- Recycling needs energy and produces
waste. - Reduced impact if product is reused.
What finite resource is used to produce
polymers?
Crude oil
What are biodegradable and
non-biodegradable materials?
Biodegradable: can be decomposed
(broken down) by microorganisms.
Non-biodegradable: can’t be
decomposed by microorganisms.
Explain how PET bottles can be recycled
PET bottles can be melted down and
remoulded into new products.
What factors affect the viability of
recycling a material?
- Finite nature of some resources.
- Availability of the material to be recycled.
- Economic and practical issues with collecting and sorting.
- Removing impurities.
- Transport and processing energy requirements.
- Demand for new product.
- Environmental impact.
What are the advantages of recycling
metals?
- Fewer mines and quarries needed to obtain ores. - Less noise and dust produced. - Lower impact on natural habitats. - Metal ores will last longer.
What are the disadvantages of recycling
metals?
- Workers, vehicles and fuel needed to collect used metal. - Difficult to sort. - Sorted metal may need transporting before it can be processed further.
