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Chemistry > C4 > Flashcards

C4 Flashcards

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1
Q

what is brittle?

A

Snaps, rather than changing
shape, when stressed.

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2
Q

what is stiff?

A

difficult to bend or stretch

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3
Q

what is strong?

A

hard to pull apart or crush

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4
Q

what is hard?

A

difficult to dent or scratch

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5
Q

what is flexible?

A

bends easily w/o snapping or breaking

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6
Q

wghat is durable?

A

lasts a long time and doesnt wear away

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7
Q

what is dense?

A

mass per unit volume of a material

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8
Q

what is malleable?

A

able to be hammered or pressured into shape without breaking or cracking

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9
Q

what is an conductor?

A

an object or type of material that allows the flow of charge or heat in one direction

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10
Q

what is an insulator?

A

an object or type of material that does not allow the flow of charge or heat

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11
Q

at uis tensile strength?

A

how much a material can resist a pulling force

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12
Q

what is compressive?

A

how much a material can resist a pressing force

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13
Q

what is strength?

A

how good a material is at resisting force

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14
Q

what are the 4 classes of material?

A

ceramics, plymers, metsls, composites

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15
Q

what is a composite?

A
  • a material made up of two or more separate materials.
  • once finished, the composite will have unique properties when compared to the starting materials
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16
Q

what is an alloy?

A

a mixture containing one or more metal elements

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17
Q

what are examples of alloys?

A

steel, amalgam, brass, duralumin, alnico

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18
Q

an example of a composite

A

concrete

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19
Q

qualities of ceramics

A

high melting points, hard, strong

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20
Q

qualities of polymers

A

strong, tough, durable, insulators

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21
Q

qualities of metals

A

conductors, malleable, high melting and boiling points, high density

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22
Q

qualities of composites

A

high strength, low density, durable

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23
Q

what are polymers?

A

large molecules made from small units (monomers)

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24
Q

what is low density polyethene?

A

flexible polymer produced with moderate temperature, high pressure and catalyst

25
Q

what is high density polyethene?

A

rigid polymer, made with a lower temperature and pressure and a different catalyst

26
Q

what are the properties of giant covalent structures?

A
  • high melting points and boiling points as lots of energy are needed to break the covalent bonds in the structure.
  • 1 giant structure
27
Q

what properties does diamond have?

A
  • 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
28
Q

what is nanotechnology?

A

the study of extremel small substances called nanoparticles

29
Q

how are nanoparticles measured?

A

nanometres

30
Q

waht are the main propertires of nanoparticles?

A
  • small size
  • high surface area to volume ratio, meainging there is more space fore the reaction to happen
31
Q

how are nanoparticles used?

A

clothing, sunscreen, self-cleaning windows, sports equipment, packaging

32
Q

how are np used in clothing?

A
  • socks have np of silver for its antibac properties
  • stain resistant fabrics help reduce water and energy used in washing clothes
33
Q

how are np used in cosmetics?

A

e.g sun tan cream and deodorant. They make no white marks.

34
Q

what are risks of nanoparticles?

A
  • 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
35
Q

what is buckminsterfullerene?

A

-C60 (60 carbon atoms)
- hollow ball made of carbon atoms arranged in hexagons and pentagons

36
Q

what are allotropes of carbon?

A

graphene, nanotube, fullerene, diamond, graphite

37
Q

why do fullerenes have high melting and boiling points?

A

they have a giant covalent structure

38
Q

why is graphene transparent?

A

it is only one atom thick

39
Q

why does graphene have a low density?

A

ther is a low mass to volume ratio

40
Q

why does graphene have high strength

A

because of its giant structure and covalent bonds

41
Q

why is graphene a good conductor of electricity?

A

carbon atoms only form three bonds so electrons are delocalised across the entire sheet

42
Q

why is graphene flexible?

A

it is only a single sheet of layered carbon atoms

43
Q

what is oxidation?

A

loss of electrons
gain of oxygen

44
Q

what is reduction?

A

gain of electrons
loss of oxygen

45
Q

what is a redox reaction?

A

when oxidation and reduction take place at the same time

46
Q

what is a life cycle asssesment?

A

provides a cradle environment to grave analysis of the impact of a manufactured product on the environment

47
Q

are lca’s good?

A

yes as they help to show us how much energy is useful and wasted and helps us to find better alternatives

48
Q

what are the main stages of a life cycle assesment?

A

making materials
manufacture
transporting the product
using the product
disposing the product

49
Q

what is open looped recycling?

A
  • 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
50
Q

what is closed looped recycling?

A
  • 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
51
Q

what is PET?

A

polyethylene terephthalate

52
Q

advantage of closed loop

A

can be reused many times w/o devaluing

53
Q

disadvantage of closed loop

A

veryu expensive
lots of energy neeed for depolymerisation

54
Q

what is corrosion?

A

destruction of materials by chemical reactions with substances in the
environment (e.g. rusting)
- water and oxygen

55
Q

how can you combat corrosion?

A

Rusting can be prevented by excluding oxygen and water e.g. by:
o painting
o coating with plastic
o using oil or grease

56
Q

what is an allotrope?

A

different structural forms of the same element in same physical form

57
Q

properties of diamond

A

-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

58
Q

properties of graphite

A

-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

59
Q

what technology uses fullerenes?

A

nanotech

Chemistry (4 decks)

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