C4 Flashcards
what is brittle?
Snaps, rather than changing
shape, when stressed.
what is stiff?
difficult to bend or stretch
what is strong?
hard to pull apart or crush
what is hard?
difficult to dent or scratch
what is flexible?
bends easily w/o snapping or breaking
wghat is durable?
lasts a long time and doesnt wear away
what is dense?
mass per unit volume of a material
what is malleable?
able to be hammered or pressured into shape without breaking or cracking
what is an conductor?
an object or type of material that allows the flow of charge or heat in one direction
what is an insulator?
an object or type of material that does not allow the flow of charge or heat
at uis tensile strength?
how much a material can resist a pulling force
what is compressive?
how much a material can resist a pressing force
what is strength?
how good a material is at resisting force
what are the 4 classes of material?
ceramics, plymers, metsls, composites
what is a composite?
- a material made up of two or more separate materials.
- once finished, the composite will have unique properties when compared to the starting materials
what is an alloy?
a mixture containing one or more metal elements
what are examples of alloys?
steel, amalgam, brass, duralumin, alnico
an example of a composite
concrete
qualities of ceramics
high melting points, hard, strong
qualities of polymers
strong, tough, durable, insulators
qualities of metals
conductors, malleable, high melting and boiling points, high density
qualities of composites
high strength, low density, durable
what are polymers?
large molecules made from small units (monomers)
what is low density polyethene?
flexible polymer produced with moderate temperature, high pressure and catalyst
what is high density polyethene?
rigid polymer, made with a lower temperature and pressure and a different catalyst
what are the properties of giant covalent structures?
- high melting points and boiling points as lots of energy are needed to break the covalent bonds in the structure.
- 1 giant structure
what properties does diamond have?
- each carbon atom in diamond is bonded to 4 other carbon atoms by strong covalent bonds, giving it a high melting point
- hard
- doesnt conduct electricity
what is nanotechnology?
the study of extremel small substances called nanoparticles
how are nanoparticles measured?
nanometres
waht are the main propertires of nanoparticles?
- small size
- high surface area to volume ratio, meainging there is more space fore the reaction to happen
how are nanoparticles used?
clothing, sunscreen, self-cleaning windows, sports equipment, packaging
how are np used in clothing?
- socks have np of silver for its antibac properties
- stain resistant fabrics help reduce water and energy used in washing clothes
how are np used in cosmetics?
e.g sun tan cream and deodorant. They make no white marks.
what are risks of nanoparticles?
- small size makes it easy to breathe in
- once in the body, they might catalyse reactions that are harmful. due to the small size, they could react with cells
- not all risks have been researched
- nanoparticles that go down the drain can affect living organisms
what is buckminsterfullerene?
-C60 (60 carbon atoms)
- hollow ball made of carbon atoms arranged in hexagons and pentagons
what are allotropes of carbon?
graphene, nanotube, fullerene, diamond, graphite
why do fullerenes have high melting and boiling points?
they have a giant covalent structure
why is graphene transparent?
it is only one atom thick
why does graphene have a low density?
ther is a low mass to volume ratio
why does graphene have high strength
because of its giant structure and covalent bonds
why is graphene a good conductor of electricity?
carbon atoms only form three bonds so electrons are delocalised across the entire sheet
why is graphene flexible?
it is only a single sheet of layered carbon atoms
what is oxidation?
loss of electrons
gain of oxygen
what is reduction?
gain of electrons
loss of oxygen
what is a redox reaction?
when oxidation and reduction take place at the same time
what is a life cycle asssesment?
provides a cradle environment to grave analysis of the impact of a manufactured product on the environment
are lca’s good?
yes as they help to show us how much energy is useful and wasted and helps us to find better alternatives
what are the main stages of a life cycle assesment?
making materials
manufacture
transporting the product
using the product
disposing the product
what is open looped recycling?
- collect recycled plastic
- sort and clean it
- grind into flakes
- separate contaminants
- process into sheets and
fibres - make new products like
carpet fibres and non food
containers
what is closed looped recycling?
- sort and clean PET bottles
and containers - convert the polymer back into
its monomers - repolymerise the pure
monomer - use polymer granules to
make new food grade
products
what is PET?
polyethylene terephthalate
advantage of closed loop
can be reused many times w/o devaluing
disadvantage of closed loop
veryu expensive
lots of energy neeed for depolymerisation
what is corrosion?
destruction of materials by chemical reactions with substances in the
environment (e.g. rusting)
- water and oxygen
how can you combat corrosion?
Rusting can be prevented by excluding oxygen and water e.g. by:
o painting
o coating with plastic
o using oil or grease
what is an allotrope?
different structural forms of the same element in same physical form
properties of diamond
-each carbon atom is bonded to 4 other carbon atoms
- each covalent bond is strong so needs lots of energy to be broken
- doesn’t conduct electricity as there are no free ions or electrons
properties of graphite
-each carbon atom is bonded to 3 other carbon atoms
- arranged in hexagons tat from large flat sheets, then on top of one another but are held very weakly as there are no bonds between them
- this makes them free to slide over each other and us why it is soft
- high melting point as each layer is strongly held by covalent bonds
- one spare electron that is delocali88sed which allows it to conduct heat and electricity
- one single layer is graphene
what technology uses fullerenes?
nanotech
