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Chemistry AQA GCSE (Separate) > 2: Bonding, Structure, and the Properties of Matter > Flashcards

2: Bonding, Structure, and the Properties of Matter Flashcards

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1
Q

what are the three types of bonding?

A

ionic, covalent, metallic

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2
Q

how does ionic bonding work?

A

metal atom reacts with a non-metal atom; electrons in the outer shell of the metal atom are transferred; metal atoms become positively charged ions; non-metal become negatively charged ions; the ions produced have noble gas configuration

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3
Q

what is the structure of an ionic compound?

A

lattice structure consisting of regular arrangement of alternating positive & negative ions; ions are closely packed together; strong electrostatic forces of attraction present between the oppositely charged ions; these act in all directions

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4
Q

what are negative ions called?

A

anions

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5
Q

what are positive ions called?

A

cations

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6
Q

what are the limitations of a dot-cross diagram?

A

does not show how the ions are arranged in space; don’t show the relative sizes of the atoms; do not show the intermolecular forces

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7
Q

what are the limitations of a ball and stick diagram / 3D models?

A

does not show bonds as forces, but as sticks - also creates illusion of space; not to scale; doesn’t show the forces of attraction between the ions; doesn’t show the movement of electrons to form the ions; 3D models - can’t see inside of the model

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8
Q

what are the limitations of a 2D model?

A

does not show where the ions are located on the other layers/the molecules shape; not to scale

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9
Q

how does covalent bonding work?

A

non-metal atoms share pairs of electrons - strong bond

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10
Q

what is the structure of a metal?

A

lattice structure; outer electrons become delocalised and are free to move throughout the structure; this means to atoms become positive ions

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11
Q

describe the properties of a solid

A

strong forces of attraction between particles; particles packed very closely together in a fixed, regular pattern; atoms vibrate about a fixed position; fixed volume and shape; high density; particles only have a small amount of energy

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12
Q

describe the properties of a liquid

A

weaker attractive forces than in solids; irregular, unfixed pattern - move and slide past each other - adopt the shape of the container they’re in; able to flow; fixed volume but not a fixed shape; moderate to high density; particles have more energy than those in a solid but less than gaseous particles

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13
Q

describe the properties in a gas

A

no intermolecular forces; random movement; no defined pattern; far apart and move quickly in all directions; collide with each other and with the sides of the container (pressure); no fixed volume; can be compressed; low density; highest amount of energy

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14
Q

if a substance’s temp is below it’s melting point, what state is it?

A

solid state

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15
Q

what is particle theory?

A

matter changes state depending on the energy and forces present between the particles in the substance; the amount of energy needed to change from a solid to a liquid and from a liquid to a gas depends on the relative strength of the forces acting between the particles - the stronger the forces between the particles the higher the melting point and boiling point

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16
Q

what are the limitations of particle theory?

A

considers all particles to be small, solid and inelastic spheres; doesn’t consider the difference caused by different particles such as atoms, ions or molecules or mixtures of all three; fails to consider the intermolecular forces that exist between different particles in different substances

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17
Q

what are the properties of ionic compounds?

A

high melting and boiling points due to the presence of strong electrostatic forces acting between the oppositely charged ions - require a lot of energy to overcome; when melted or dissolved in water, they conduct electricity - ions are free to move and so charge can flow

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18
Q

what are the properties of small molecules?

A

usually gases/liquids - have relatively low melting points and boiling points; volatile; weak intermolecular forces - don’t need a lot of energy to overcome; intermolecular forces increase with the size of the molecules - as there are more electrons, so larger molecules have higher melting and boiling points; poor conductors of electricity - no free ions or electrons to move and carry charge

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19
Q

what are the properties of polymers?

A

made up repeated monomers - linked by strong covalent bonds; relatively strong intermolecular forces acting in between polymer chains so usually solid at room temperature

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20
Q

what are the properties of giant covalent structures?

A

high melting and boiling points as they have many strong covalent bonds - large amounts of heat energy needed to overcome these forces and break down bonds- (most) cannot conduct electricity as they do not have free electrons nor charged particles - exceptions of graphite

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21
Q

what are the properties of metals?

A

very high melting and boiling points and are solids at room temperature, exception of mercury - bonds are very strong and are a result of the attraction between the positive metal ions and the negative delocalised electrons within the metal lattice structure; usually insoluble in water although some do react with it; good conductors of heat & electricity - delocalised electrons layers of atoms in metals can slide over each other - malleable and can be hammered and bent into shapes

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22
Q

what are alloys?

A

mixtures of metals with either other metals, or non-metals e.g. carbon, where the metals are mixed together physically but are not chemically combined

23
Q

what are the properties of alloys?

A

have more strength, hardness or resistance to corrosion or extreme temperatures - than metals

24
Q

why do alloys have different properties to metals?

A

they contain atoms of different sizes, which distorts the regular arrangements of atoms - makes it more difficult for the layers to slide over each other, so they are usually much harder than pure metals

25
Q

why are metals good electrical conductors?

A

they have free electrons available to move and carry charge throughout the metal lattice structure.

26
Q

why are metals good thermal conductors?

A

energy can be transferred by the delocalised electrons

27
Q

describe the structure of diamond

A

each carbon atom bonds with four other carbons, forming a tetrahedron

28
Q

describe the properties of diamond

A

does not conduct electricity; has a very high melting point; extremely hard and dense

29
Q

why does diamond have its properties?

A

all the covalent bonds are identical, very strong and there are no weak intermolecular forces - making it very hard and meaning it has a high melting point, as lots of energy is needed to overcome the covalent bonds; there are no free electrons - it cannot conduct

30
Q

what are the uses of diamond?

A

used in jewellery; for coating blades in cutting tools.
cutting edges of discs used to cut bricks and concrete are tipped with diamonds; heavy-duty drill bits and tooling equipment are also diamond tipped - due to it’s hardness

31
Q

describe the structure of graphite

A

each carbon atom is bonded to three others forming layers of hexagonal shaped forms, leaving one free electron per carbon atom

32
Q

why can graphite conduct electricity?

A

there is one free electron per carbon atom; these exist in between the layers and are free to move and carry charge

33
Q

describe the properties of graphite

A

conducts electricity and heat; as a very high melting point; soft and slippery, less dense than diamond

34
Q

why does graphite have these properties?

A

has free electrons to conduct; strong covalent bonds between carbon atoms require lots of energy to overcome; the layers are connected to each other by weak intermolecular forces only - the layers can slide over each other making graphite slippery and smooth

35
Q

what are the uses of graphite?

A

used in pencils; as an industrial lubricant, in engines and in locks; used to make non-reactive electrodes for electrolysis

36
Q

describe the structure of graphene

A

a single layer of graphite which is a sheet of carbon atoms covalently bonded forming hexagonal shapes

37
Q

describe the properties of graphene

A

extremely strong; extremely light; can conduct electricity

38
Q

why does graphene have these properties?

A

strong - it only has strong covalent bonds, no intermolecular forces; light - only one atom thick layer; conduction - has a free electron per carbon atom which can move and carry charge

39
Q

what are the uses of graphene?

A

useful in fabricating composite materials; in electronics

40
Q

describe the structure of fullerene

A

consist of molecules made only of carbon and which form hollow tubes or spheres

41
Q

what are the uses of fullerene and why?

A

useful for targeted drug delivery systems - can be used to trap other molecules by forming around the target molecule and capturing it; useful for trapping catalyst molecules onto their surfaces making them easily accessible to reactants so catalysis can take place - have a huge surface area; some are excellent lubricants and are used in many industrial processes

42
Q

describe the structure of Buckminsterfullerene (“Buckyballs”)

A

60 carbon atoms are joined together forming 20 hexagons and 12 pentagons which produce a hollow sphere

43
Q

what is a nanotube?

A

Graphene that has been rolled into a cylinder to produce a type of fullerene

44
Q

describe the properties of nanotubes

A

high tensile strength and are resistant to breaking or stretching; conducts electricity

45
Q

give the uses of nanotubes

A

useful in composites and specialised materials, electronics and nanotechnology

46
Q

how big are nanoparticles?

A

between 1 and 100 nanometres in size (diameter); usually contain only a few hundred atoms

47
Q

how big are coarse particles?

A

2,500 to 10,000 nm (diameter) - often referred to as dust

48
Q

how big are fine particles

A

100 - 2,500 nm (diameter)

49
Q

why do nanoparticles make good catalysts?

A

they have a very high surface area to volume ratio;

the higher the ratio then the more surface area is available for reaction = the better the catalyst.

50
Q

how can the s.a. to v. ratio be calculated?

A

ratio = surface area / volume

51
Q

what are the uses of nanoparticles?

A

mainly used in catalysis - high surface area to volume ratios; titanium dioxide in nanoparticle form is used in sunscreens as it blocks UV light; fullerenes are used in medicine and drug design - more easily absorbed than other particles and can deliver drugs to target areas more effectively; also used in electronic circuitry and as coatings for artificial limbs and joints; nanoparticles of silver are sprayed onto the fibres of medical clothing and surgical masks - gives them the flexibility of a material & antibacterial properties of silver metal.

52
Q

give an example of how the same chemical has different properties in bulk and nanoparticle form

A

titanium dioxide in nanoparticle form is used in sunscreens as it blocks UV light; also used in bulk form is used as a white pigment in paints

53
Q

what are the risks of using nanoparticles?

A

still a lot of unknown factors and potential risks; lack of understanding on how they may affect health - although there haven’t been any serious short term side effects, there could be long term side effects which we haven’t detected yet as they haven’t been in use long enough; a small amount of toxicity in a particular nanoparticle would be multiplied due to the high surface area to volume ratio; this coupled with the fact that they are not easily disposed of by the body are a cause for caution in the medical application of nanoparticles.

Chemistry AQA GCSE (Separate) (11 decks)

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