C3 Structure and bonding Flashcards
The ionic bonds between the charged particles result in an arrangement of ions called what?
a giant structure or giant lattice
What is between the oppositely charged ions in giant structures of ions arranged in a lattice?
attractive electrostatic forces that act in ALL directions and are very strong
What does the attractive electrostatic forces do?
holds the ions in the lattice together very tightly
It takes a lot of what to break up a giant ionic lattice and why?
Energy- lots of strong ionic bonds to break
How do we separate ions?
have to overcome all those electrostatic forces of attraction acting in all directions
Hard to separate means ionic compounds have..
high boiling+melting points
What happens to the ions once enough energy is supplied to separate the ions from the lattice
They become mobile and start to move around (solid to liquid)
Ions are ___ to ___ anywhere in the liquid
free
move
Why can’t a solid ionic compound conduct electricity?
ions are held in fixed positions in the lattice; ions cannot move around
They vibrate on the spot
Many but not all ionic compounds will dissolve in water. When an ionic compound is dissolved in water, what happens?
lattice is split up by the water molecules. -> ions free to move around within the solution formed
What is molten?
liquefied by heat.
What is covalent bonding
When non-metals react together, their atoms share pairs of electrons to form molecules
The atoms of non-metals generally tend to gain what?
gain electrons to achieve stable electron structures
When non-metals react together, neither atom can give away electrons. So where do they get their electronic structure?
They get their electronic structure of a noble gas by sharing electrons
In covalent bonding, the atoms in the molecules are then helped by what?
Shared pairs of electrons
The strong bond between the shared pairs of electrons are called?
covalent bonds
Many substances containing covalent bonds consist of what?
small molecules e.g. h20
Some covalently bonded substances are very different to those small molecules. What do they have?
giant structures - where huge numbers of atoms are held together by a network of covalent bonds
what are these covalent bonds in giant structures sometimes referred as?
macromolecules
Diamond has what sort of structure?
giant covalent structure
In diamond. how many covalent bonds does the carbon atom form?
4 covalent bonds w its neighbours
Since the carbon has 4 covalent bonds, what does this result in?
a rigid giant covalent lattice
What are dot and cross diagrams for?
to show bonding in covalent compounds
Electrons drawn in the ____ between the outer orbitals of two atoms are ____ between atoms in covalent bonding
overlap
shared
What are dot and cross diagrams useful for?
showing which atoms the electrons in a covalent bond come from
What is a drawback of dot and cross diagrams
Doesn’t show relative SIZES of the atoms
or how the atoms are arranged in space
Displayed formula is useful for?
shows how atoms are connected in LARGE molecules
drawback of displayed formula?
does not show 3d structure of the molecule
or which atoms the electrons in the covalent bond have come from
What does the 3D models show?
the atoms, the covalent bonds and their ARRANGEMENT in space
drwback for 3d models?
confusing for large molecules where there are lots of atoms to include
does not show where the electrons in the bonds have come from either
The atoms within the molecules are held together by very ___ ______ bonds but the forces of _____ between these molecules are very ____
strong covalent
attraction
weak
To melt or boil a simple molecular compound, do you need high or low boiling/melting point?
low- feeble intermolecular forces and not the covalent bonds, molecules are easily parted
As molecules get bigger..
intermolecular forces increases - more energy needed
Molecular compounds don’t of what and why?
conduct electricity- AREN’T CHARGED- no free electrons
What are some properties of a giant covalent structure that gives substances?
high mp and bp
insoluble in water
Apart from graphite, hard and does not conduct electricity
In graphite, carbon are only bonded to what?
three other carbon atoms
What does the carbons form in graphite
hexagons, arranged in giant layers
In graphite, there are no _____ bonds between the layers only weak ______ forces, so the layers can _____ over each other quite easily
covalent
intermolecular
slide
Graphite is a ___ material that feels ______ to the touch
soft
slippery
As the carbon atoms in graphite’s layers are arranged in hexagons, each carbon forms what?
three strong covalent bonds
Carbon atoms have ___ electrons in their outer shell available for _____. This leaves one space outer ______ on each carbon in graphite
four
bonding
one
electron
These mobile electrons can ____ freely along the ____ of carbon atoms. The mobile electrons found in graphite are called?
freely
layers
delocalised electrons
Mobile electrons between the layers of graphite no longer what?
belong to any one particular carbon atom. They behave rather like the electrons in a metallic structure
What do these delocalised electrons allow graphite to do?
conduct electricity- electrons will drift away from the negative terminal of a battery and towards its positive terminal when put into an electrical circuit
Graphite is also an excellent conductor of what and why?
Thermal conductor
Energy is transferred to the delocalised electrons, rapidly transfer the energy along the LAYERS in the graphite
Why can’t diamond conduct electricity?
their atoms have no free electrons, as all their outer shell electrons are involved in a covalent bonding
What are fullerenes
structures where carbon atoms join together to make hollow cages
Cyndrical fullerenes called carbon nanotubes can also be produced, they form what?
incredibly thin cylinders, whose length is much greater than their diameter
What useful properties do incredibly thin cylinders have?
high tensile strength
high electrical conductivity and high thermal conductivity
The atoms in metals are built up as?
layer upon layer in a regular pattern
Regular pattern in atoms of metals mean?
that metals form crystals
What is metal another example of?
giant structures
A metal has a lattice of…
positively charged ions
How are the metal ions arranged?
regular layers, on top of another
What can the outer electrons from each metal atom do?
easily move throughout the giant strucutre
In metallic structures, the outer electrons form what?
a ‘sea’ of free-moving electrons surrounding the positively charged metal ions
What bonds the metal ions to each other?
Strong electrostatic attraction between the negatively charged electrons and the positively charged ions
The sea of delocalised electrons are no longer ____ with any particular ____ __ in the giant metallic structure
linked
metal ion
What is an alloy
a mixture of two or more elements
Describe why metals can be bent, shaped and pulled out into wires when forces are applied?
layer of atoms (positively charged ions) slide over each other easily
What word can be used to describe a material that can be hammered into shape and drawn out into wire?
malleable
ductile
Using knowledge of metal structures explain why alloying a metal can make the metal harder?
differently sized atoms inserted
regular arrangement of metal atoms (positively charged ions) disrupted
more difficult for laters to move
Explain why metals are good conductors of thermal energy and electricity?
sea of delocalised electrons drifting through metal’s giant structure.
mobile delocalised electrons gain energy when heated
Explain why aluminium has a higher melting point than sodium
each aluminium donates 3 electrons into ‘sea’ of mobile delocalised electrons. Forming Al 3+ ions
Comparted to one electron in lattice of Na+ ions
Electrostatic forces of attraction in metallic bonding stronger in aluminium because of a higher charge + more electrons involved in metallic bonding
What is meant by nanoscience?
study of particles between 1 and 100 nm in size
explain why the properties of nanoparticles of a material may differ from the properties of a bulk material
normal materials: most atoms, molecules or ions exist within body of material- not exposed at surface of material
nanoparticles: proportion of particles at surface is massively increased for same mass of material so properties different
Why might nanoparticles be different from those for the same materials in bulk
have a high surface area to volume ratio, with a high percentage of their atoms exposed in their surface
Nanoparticles may result in smaller quantities of materials such as ____, needed for what?
catalysts
industrial uses
Give two uses of silver nanoparticles
- antibactericide in fridges
- sprays in operating theatres,
- wound dressings
- on clothes
Give an adv of using nanoparticles as catalyst
large surface area to volume ratio
Why are some people concerned about the use of nanoparticles as catalysts?
EXPLOSIONS caused by sparks
HEALTH PROBLEMS if breathed in if nanoparticles escape into air / environment
Explain two uses of nanoparticles in cosmetic products for the skin
Sun-screens- block UV light
face-cream: deliver active ingredients deeper beneath surface of skin
How can nanoparticles possibly help to fight cancers
delivers drugs to the tumour and is then absorbed, then absorbs energy from lasers to damage tumour by affecting its proteins
