bonding, structure and the properties of matter Flashcards
ionic bonding
metal + non-metal
- metal atoms lose electrons to become positively charged ions
- non-metal atoms gain electrons to become negatively charged ions
describe an giant ionic structure
- lattice consisting of a regular arragemnt of alternating charged ion
- ions held together by strong electrostatic forces
-^ high melting and boiling points
covalent bonding
non-metal + non-metal sharing eletrons to gain full outer shells
covalent bonds are very strong
why are simple covalent molecules weak
weak intermolecular forces inbetween each molecule
molecule vs compound
compounds- different elements!!!
what are large covalently bonded molecules?
polymers
name 3 giant covalent structures
- graphite
- diamond
- silicon dioxide
2 advantages and 2 disadvantages of dot and cross diagrams
advantages:
- useful for illustrating share of electrons
- indicates which atom the bonding electrons come from
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disadvantages
- fails t illustrate 3d arragement of atoms and electron shells
- doesnt inidicate relatives sizes of atoms
2 advantages and 2 disadvantages of ball and stick model
advantages
- useful for illustrating arragemnt of atoms in 3D space
- especially useful for visualising shape of molecule
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disadvantes
- fails to indicate movement of electrons
- distance from atoms not accurate
2 advantages and 2 disadvantages of 2d representations of molecules
advantages
- 2d representations that are simpler versions of ball and stick model
- shows what atoms in molecule and how they are connected
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disadvantages
- fails to show relative size of atoms and bonds
- doesnt represent the shape and how it looks 3d
metallic bonding- describe it in a metal
- regular arragement of positive ions
- delocalised electrons lost from ions shared across structure
at what point do freezing and condesning take place?
freezing- metling point
condensing- boiling point
what is particle theory?
can help explain that the amount of energy needed to change state from a solid to liquid and liquid to gas depends on the strength of forces between the particles of the substance
the stronger the force betweeen the particles of a substance…
the higher the energy required fro melting and boiling
limitations of particle theory
particles are represented by solid inelastic spheres that have no forces inbetween them
properties of ionic compounds
2
- high melting and boiling points- giant structures and strong electrostatic forces iof attraction between ions
- when molten or dissolved in water- can conduct electricity- ions free to move
properties of small molecules
- substances consisting of small molecules have low m b points
- weak intermolecular forces but strong covalent
- intermolecular forces increase with size of molecules
- dont conduct electricty because they dont have an overall charge
what are polymers made from and how are they bonded both in atoms and units
monomers bonded by covalent bonds
atoms in polymer molecules bonded by covalent
properties of metal
(bonding)
- high m b points- strong electrostatic forces between ions and electrons
- malleable- layers of positive ions slide over each other when force is applid
what is an alloy?
mixture of two or more metals or metal witjh a non-metal like carbon
alloys compared to pure metals
- they are harder and stronger
- resitant to corrosion or extreme temperatures
why are alloys harder than pure metals?
contains different sized atoms that make it difficult for layers of atoms to slide over each other
how do metals concuct electricty?
delocalised electrons carry charge THROUGH electron
describe the structure of diamond
- carbon atoms bonded to 4 other carbons
- no intermoleculr forces
properties of diamond
- do not conduct electricity-** no free moving partices **to carry charge
- very high meltinng point- strong covalent bonds between each carbon
- very hard and dense- strong covalent bonded to 4 carbons
allotropes of carbon
- diamond
- graphite
- graphene
- fullerene
describe structure of graphite
- carbon atom covalently bonded to 3 other carbons
- 1 delocalised electron for each carbon
- layers of hexagons attracted by weak intermolecular forces
properties of graphite
- conduct electricity- deloalised electron able to carry charge through structure
- high melting point- strong covalent
- slippery- lyayers can slide over each other due to weak intermolecular forces- means can be used as pencil or lubricant
describe structure of graphene
- single layer of graphite- sheet of carbon atoms covalently bonded
- delocalised electrons
properties of graphene
- strong but light- strong covalent bonds unbroken
- good conductor- delocalised electrons
- flexible- the covalent bonds can bend without breaking
- transparent- absorbs some light
structure of fullerenes
and what are they
- either hollow tubes or spheres
- based onhexagonal rings BUT can be 5 or seven
- nanoparticles
first fullerene to be discovered
buckminsterfullerene
- hollow sphere
- 60 carbon atoms bonded
uses of fullerenes
- targeted drug delivery- can trap molecules
- trapping catalyst molecules onto surfaces- big surface area
carbon nanotube
graphene rolled into cylinder
high lenth to diameter ratios
why are nanotubes useful and what are they used in?
- resistant to breaking or stretching
- conduct electricty
- composites
- electronics
- nanotechnology
- specialised materials
diameters of coarse, fine and nano particles
and what ar coarse particles referred to as?
coarse- 2500-10000 nm
fine- 100-2500 nm
nano-1-100 nm
dust
what happens to tthe surface area to vol ratio if side of cube decreased by 10?
increase by 10
why are nanoparticles different to the bulk chemical its made from?
- high surface area to volume ratio whic means smaller amounts are reuqired for it to be as effectibe
high sa- biger area for reactions
uses of nanoparticles and why
- catalysts- high sa:v
- cosmetics- suncream & deodrants as leave no white marks
- medicien and drug deliveries- more easily absorbed & can deliiver drugs to target areas more effectively
- small electrical circuits - conduct electricty
disadvantages of nanoparticles
- in early stages so still unkown factors and potential risks
- lack of understanding how they affect health
- long term side effects potentially
- ## small amount of toxicity in nanoparticle would be multiplied beaccuse of high sa:v
