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chemistry > structure and bonding > Flashcards

structure and bonding Flashcards

1
Q

what holds ions in a a lattice tightly in giant ionic compounds

A

strong electrostatic forces of attractions between the oppositely charged ions (which act in all directions)

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2
Q

why do giant ionic compounds have a high melting and boiling point

A

as they have strong electrostatic forces of attraction acting in all directions, this means it would require lots of energy to overcome these forces and separate the ions in their lattice making them have high melting and boiling points

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3
Q

why can giant ionic compounds conduct electricity when the electrostatic forces are over come

A

as when the ions are separated from the lattice the IONS become mobile and are free to move, these freely moving ions can carry electric charge

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4
Q

why cant ionic solids conduct electricity

A

as the ions are in fixed positions and can only vibrate as they cannot move

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5
Q

properties of ionic compound’s

A
  • high melting point and boiling point
  • can conduct electricity
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6
Q

cons of 2d ball and stick model

A

do not represent the shape of the molecule or the correct angles the atoms are bonded at

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7
Q

pro of dot and cross model

A
  • allows you to see which electron comes from which atom
  • shows that electrons are found in-between atoms
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8
Q

cons of dot and cross model

A
  • not all electrons look the same
  • electrons are not in fixed positions as they are constantly moving
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9
Q

why do simple molecules have low boiling and melting points

A

as they have weak intermolecular forces this means that it does not require lots of energy to overcome these forces

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10
Q

why do larger molecules have a higher melting point than smaller molecules

A

as when a molecule increase their intermolecular forces become stronger so they require more energy to overcome these forces (so id you go down a group on non metals the melting and boiling point increases)

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11
Q

why cant simple molecules conduct electricity

A

as they do not have charged ions or delocalised electrons to carry the electrical charge (but they can conduct electricity when reacted in water as they form aqueous ions)

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12
Q

what is the lattice in simple molecular held by

A

strong covalent bonds

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13
Q

why are metals malleable

A

as metal are arranged in layers, these layers can easily slide over each other making the metal very malleable

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14
Q

why do metals have a high melting and boiling points

A

as they have strong metallic bonds between the oppositely charged ions, this means it would require lots of energy to overcome these forces

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15
Q

why can metals conduct electricity and thermal energy

A

as they have delocalised electrons which can move freely throughout the structure and carry electrical and thermal charge

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16
Q

what is an allotrope

A

an allotrope is two substances made up of the same element at the same physical state but have different structures

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17
Q

what are fullerenes

A

fullerenes are allotropes of carbon made by bending sheets of graphene into hollow like structures

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18
Q

what are cylindrical fullerenes called and what is there ratio

A

nanotubes
they have a high length to diameter ratio

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19
Q

what are cylindrical fullerenes called and what is there ratio

A

nanotubes
they have a high length to diameter ratio

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20
Q

carbon nanotube properties

A
  • good thermal and electrical conductors as they have delocalised electrons
  • high tensile strength
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21
Q

uses of fullerenes spheres

A
  • can be used to deliver drugs due to their hollow like structures
  • used as catalyst because of their high surface area to volume ratio
  • used as lubricant because of their high surface area to volume ratio
22
Q

uses of nanotubes

A
  • can be used in electronics as as they conduct electricity
  • can be used to strengthen materials due to their high strength to weight ratio
23
Q

what is graphene

A

a single layer/sheet of graphite

24
Q

advantages of graphene

A
  • low density
  • good thermal and electrical conductor
  • most reactive carbon
  • very strong
25
Q

uses of graphene

A
  • electrical uses such as computer chips since it has delocalised electrons to conduct electricity
26
Q

what are giant covalent structures

A

huge networks of atoms held together by covalent bonds

27
Q

properties of giant covalent structures

A
  • high melting and boiling point as they have strong covalent bonds so it would require lots of energy to overcome these covalent bonds
  • cant conduct electricity (except graphite)
  • very strong
  • insoluble in water
28
Q

how many carbon atoms are covalently bonded in graphite

A

3

29
Q

why is graphite soft and slippery

A

as there are weak intermolecular forces between the layers this enables the layers to slide over each other making graphite soft and slippery

30
Q

why can graphite conduct thermal and electrical energy

A

as in graphite the carbon atoms are only bonded to 3 other carbon atoms, this make graphite have a delocalised electron as carbon is supposed to have 4 electrons in their outer shell. This delocalised electron can carry electric and thermal energy

31
Q

properties of graphite

A
  • high melting and boiling point
  • can conduct electricity
32
Q

how many carbon atoms are covalently bonded in diamond

A

4

33
Q

why cant diamond conduct electrical and thermal electricity

A

as it does not have delocalised electrons

34
Q

why are alloys very strong

A

as it has different sized atoms this distorts the regular lattice making it very strong as the layers cannot slide over each other

35
Q

what are nanoparticles

A

VERY small particles

36
Q

diameter of coarse particles

A

2.5 x 10-6 (dont know why we need to know this but it has been a question before)

37
Q

uses of nanoparticles an explanation (5 points)

A
  • catalysts as the have a high surface area to volume ratio so we would need much less nanoparticles to speed up a reaction than normal particles
  • deliver rugs as they are so small so they could deliver drugs in the cells
  • in small electrical circuits as they can conduct electricity
  • in the fibres of surgical masks or to clean hospitals as nanoparticles containing silver has antibacterial properties
  • for sunscreen as it very effective to block UV rays since it provides better coverage on our skin because of its large surface area to volume ratio
38
Q

disadvantages of nanoparticles

A
  • effects on the body aren’t fully understood because they are so small they could enter are body and damage our cells
  • we don’t know what damage it could cause to environment id it got washed up in the sea
  • if large quantities of nanoparticles got near a spark it could cause a violent explosion
39
Q

properties of solids

A
  • strong forces of attraction between particles which hold them in a fixed position
  • definite shape and volume
  • particles vibrate in its fixed position
40
Q

what happens when a solid is heated

A

energy is transferred from the surroundings to the solid, the particles vibrate more, weakening the forces of attractions and then bonds (forces of attractions) are broken converting it into a liquid

41
Q

properties of a liquid

A
  • weak forces of attraction between particles
  • definite volume
  • shape can be changed
  • arranged randomly
42
Q

what happens when you heat a liquid

A

energy is transferred from the surroundings to the liquid, the particles vibrate more, weakening the forces of attractions and then bonds (forces of attractions) are broken converting it into a gas

43
Q

properties of a gas

A
  • very weak forces of attraction between particles
  • dont have a definite shape or volume
44
Q

what happens when you heat up a gas in a container

A

it will either expand or the pressure will increase

45
Q

what happens when you cool a gas or freeze a liquid

A

the particles wont have enough energy to overcome the forces of attraction so bonds will form between the particles forming a liquid or solid

46
Q

cons of particle models(4 points)

A
  • particles are not solid, inelastic or spheres as their ions or molecules
  • it doesn’t include any detail about the forces between the particles
  • makes assumptions that are particles are small
  • not all particles are the same size
47
Q

pros of particle model

A
  • easy to understand
  • useful to compare between solid liquid and gas
48
Q

True or false
the melting point is the same temp at which a liquid freezes at

A

True

49
Q

True or false
the boiling point is a different temp at which a gas condenses at

A

False
the boiling point is the same temp at which a gas condenses at

50
Q

what happens to the temp when a liquid or solid is melting or evaporating

A

it remains constant until the liquid/solid has evaporated/melted

chemistry (13 decks)

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