C3 - structure and bonding Flashcards
what is the structure of a solid
fixed shape and volume
cannot be compressed
vibrate
what is the structure of a liquid
fixed volume
can flow and change shape
occupy more space than solid
what is the structure of a gas
no fixed shape or volume
compressed easily
what does particle theory describe
movement of particles
average distance between particles
how does a solid turn into a liquid
the solid is heated
the hotter it gets the more the particles vibrate
vibrations become so strong the particles break free
becomes liquid
how does a liquid become a gas
the liquid is heated
the hotter it gets the more it’s particles move
temperature rises and more energy transferred from surrounding to particles
particles escape from surface of liquid
becomes gas
what are the limitations of the particle model
the atoms, molecules, and ions that make up substances are not spherical, and have forces acting between them
atoms are mostly empty space
what is sharing electrons called
covalent bonding
what is transferring electrons called
ionic bonding
how is ionic bonding represented
a dot and cross diagram
what arrangement do ionic bonds form
giant structure
giant lattice
what ions do each of the groups form
group 1 - 1+
group 2 - 2+
group 3 - 3+ when they form ions instead of sharing electrons
group 4 - do not form ions
group 5 - 3- when they form ions instead of sharing electrons
group 6 - 2- when they form ions instead of sharing electrons
group 7 - 1- when they form ions instead of sharing electrons
group 0 - never form ions in compounds
why is it difficult to break up a giant ionic lattice
strong ionic bonds to break
electrostatic attraction holds the ions together
i.e ionic compounds have high melting and boiling points
what happens when ions become a liquid
they are attracted to oppositely charged electrodes hell in the molten compounds
properties of an ionic solid
fixed in position in giant lattice
vibrate but cannot move around
does not conduct electricity
properties of a molten ionic compound
high temperature provides enough energy to overcome many strong attractive forces between ions
ions are free to move around within the molten compound
does conduct electricity
properties of an ionic compound in a solution
ions are free to move around within the solution
does conduct electricity
between what type of element does covalent bonding happen
between non metals
give an example of a giant covalent structure
diamond
what are the weak forces between molecules called
intermolecular forces
what happens to intermolecular forces as you increase the size of a molecule
they increase
what are polymers made up of
small reactive molecules that bond to each other to form long chains
why do simple molecules not conduct electricity
they have no overall charge
what materials have giant covalent structures
diamond
graphite
silicon dioxide (silica)
properties of giant covalent structures
high melting and boiling points
insoluble in water
hard and do not conduct electricity (bar graphite)
what is the structure of graphite
giant covalent
carbon is only bonded to three other carbon atoms
form hexagons
arranged in layers
no covalent bonds between layers
layers can slide over eachother
why does graphite conduct electricity and thermal energy
hey have delocalised electrons
what are fullerenes
molecules of carbon with hollow shapes, their structures are based on hexagonal rings
what are the properties of nano tubes
high tensile strength
good conductors
what are fullerenes used for
delivering drugs in the body to treat cancer in specific parts of the body
lubricants
catalysts
what is graphene
a single sheet of carbon atoms from graphite
properties of graphene
excellent conductor
low density
strong
what could graphene be used for
new developments in the electronics industry
how are the atoms in metals arranged
later upon later in a regular pattern
what is metallic bonding
positive metal ions held together by delocalised electrons from each metal atom
what is an alloy
an alloy is a mixture of two or more elements, where at least one of which is a metal
why are free electrons like glue?
the positive ion cores are attracted to the free electrons
why are metals malleable
delocalised electron means lattice can distort
when metal atoms are struck the metals atoms slip past one another without breaking up the metals structure
why are metals ductile
the layers of metal ions can slide over each other
why do metals have high melting points
the strong electrostatic forces mean it takes a lot of energy to separate the metal ions from their fixed positions and break down the lattice
what is nanoscience
the study of particles between 1 - 100 nanometers in size
what substances are PM10
coarse particles or dust
what are fine particles described as
PM0.1 to PM2.5
properties of nano particles
highly reactive
high SA:V ratio
how can nano particles be used in glass
glass can be coated with titanium oxide (nano particles)
sunshine triggers chemical reaction that breaks down dirt that lands on window
when it rains, water spread evenly and washes dirt off
how can nano particles be used in suncream
titanium and zinc oxide get coated with silica
thickness of silica can be adjusted to atomic level
coated nano particles are more effective at blocking suns rays
how can nano particles be used in cosmetics
nano particles in face creams are absorbed deeper into skin
how can nano particles be used in medicine
tiny gold particles injected and absorbed by tumours
tumours have thin leaky blood vessels with holes large enough for gold particles to pass into, cannot get into healthy blood vessels
when laser is directed at tumour, energy is transferred to gold and they warm up quickly
temperature of tumour increases to change properties of its proteins
destroys tumour cells
what are silver nano particles used for
inhibit the growth of microorganisms
where are silver nano particles used
fridges
anti bacterial sprays
antimicrobial coatings (keyboards, wound dressings, biomedical devices, textile)
how can nanowires be used
to construct incredibly small electronic circuits
make computers with vastly improved memory capacities and speeds
how can nanotubes be used
make highly sensitive sensors
can detect tiny traces of a gas present in the breath of asthmatics before an attack
risk of nano particles due to size
large surface area makes them dangerous
if a spark is made by accident near a large quantity of the catalyst there could be a violent explosion
risk of nano particles due to amount of use
as they get used more and more they could find their way into the atmosphere
scientists believe health hazard increases as the diameter of particle decreases
breathing in tiny particles could damage lungs and enter bloodstream
risk of nano particles due to entering environment
could affect aquatic life by accumulating in organisms over time
