C2 - Structure and Bonding (mine) Flashcards
1
Q
What are the three common states of matter?
A
solid, liquid, gas
2
Q
What are the properties of solids?
A
extremely hard to compress, as there are almost no spaces between the particles
fixed shape, can not flow from place to place
3
Q
What are the properties of liquids?
A
extremely hard to compress, because the particles are close together with not many spaces between them
take the shape of their container, the particles flow over each other
4
Q
what are the properties of gases?
A
extremely easy to compress, because the particles are widely spaced
gases spread out and fill the space or their container, because the particles in a gas move quickly and randomly
5
Q
How can we change the state of a substance?
A
By putting in or taking out energy
6
Q
solid -> liquid
A
melting
energy is put in
7
Q
liquid -> gas
A
boiling
energy is put in
8
Q
gas -> liquid
A
condensing
taking away energy
9
Q
liquid -> solid
A
freezing
taking away energy
10
Q
solid -> gas
A
sublimation
energy is put in
11
Q
gas -> solid
A
deposition or desublimation
energy taken way
12
Q
Where does melting take place at?
A
the melting point
13
Q
where does freezing take place at?
A
the melting point
14
Q
where does boiling take place at?
A
the boiling point
15
Q
where does condensing take place at?
A
the boiling point
16
Q
Why do some materials have a higher melting point that others?
A
Different materials have different forces of attraction that holds the particles together, these forces needs to be broken to melt the substance
higher forces of attraction between the particles, leads to greater energy need to break them, so there is a higher melting point.
17
Q
What are the limitations of the simple particle molecule?
A
It assumes that all particles are solid spheres, which is not true
It assumes that there are no forces between the particles
18
Q
Elements react in order to …
A
achieve a full outer energy level
19
Q
Ionic bonding is when …
A
a metal reacts with a non-metal
20
Q
During ionic bonding ..
A
the outer-shell electrons
pass from one element
to the other element
so both atoms achieve a full outer-energy level
21
Q
What do ionic compounds form?
A
giant ionic lattices
22
Q
explain the structure of giant ionic lattices
A
giant ionic lattices has positive ions surrounded by negative ions
23
Q
Explain the attraction in giant ionic lattices
A
Giant ionic lattices have very strong electrostatic forces of attraction between the positive and the negative ions
24
Q
What are the properties of ionic compounds (giant ionic lattices)
A
High melting and boiling points
Conducts electricity only when they are melted or dissolved in water, not when they are solids
25
why do giant ionic lattices have high melting and boiling points?
the electrostatic forces between the positive and negative ions require a lot of thermal energy to break, as they are very strong
26
why do giant ionic lattices only conduct electricity when they're melted or dissolved in water, but not as solids?
As solids, in giant ionic lattices, the ions cannot move, they're locked in place by the strong electrostatic forces, so they cannot act as charge carriers
When the ionic compounds are melted or dissolved in water, the ions can now move and can carry the charge
27
Covalent bonding is when ...
a non-metal reacts with a non-metal
28
During covalent bonding ...
the electrons are shared between atoms in pairs
29
1 shared pair of electrons are known as ...
a single covalent bond
30
2 shared pairs of electrons are known as ...
a double covalent bond
31
Explain the structure of small covalent molecules (simple molecular substances)
the molecular substances are held together by weak intermolecular forces, however the molecules themselves are held together by strong covalent bonds
32
what are the properties of small covalent molecules?
They have low melting and boiling points, meaning that they are usually gases or liquids at room temperature
they do not conduct electricity
33
why do simple molecular substances have low melting and boiling points?
Despite, the strong covalent bonds within the molecules, between the molecules there are weak intermolecular forces. The intermolecular forces take very little energy to break. So not a lot of thermal energy is need to melt or boil the substance - it will have a low melting and boing point.
34
Why do small covalent molecules not conduct electricity?
They have no charge carriers to carry current. The molecules do not have an overall electric charge.
35
As the size of small covalent molecules increase ..
(in terms of melting and boiling point)
so does the melting and boiling points as there is more intermolecular forces that need to be broken, so more energy is needed
36
Why are giant covalent structures always solids at room temperature?
giant covalent structures have millions of strong covalent bonds (and no weak intermolecular forces).
37
describe the structure of giant covalent structures
many strong covalent bonds but no weak intermolecular forces
38
what element is diamond formed from?
carbon
39
Describe the structure of diamond?
Each carbon atom forms four strong covalent bonds.
This leads to an overall tetrahedral shape.
40
What are the properties of diamond?
Diamond has a very high melting and boiling point
Diamond does not conduct electricity
41
Why does diamond have a high melting and boiling point?
Diamond has a huge number of very strong covalent bonds (each carbon atom forms 4), these bonds take a large amount of energy to overcome, in order for the substance to be melted.
42
Why doesn't diamond conduct electricity?
Since each carbon atom is bonded with four other carbon atoms, it leaves no electron to be delocalised, there are no free electrons to carry electrical charge.
43
Graphite is a form of the element ...
carbon
44
Explain the structure of graphite
Each carbon atom is bonded to three other carbon atoms through three covalent bonds.
This means the carbon forms hexagonal rings.
Graphite contains layers of these rings, between the layers are weak intermolecular forces.
45
What are the properties of graphite?
high melting and boiling point
slippery
excellent conductor of electricity and heat
46
why does graphite have a high melting and boiling point?
graphite has many strong covalent bonds, so it takes a lot of energy to break them, this makes graphite have a high melting and boiling point
47
Why is graphite slippery?
The hexagonal rings of carbon are in layers, there are no covalent bonds between the layers only weak intermolecular forces, so the layers can easily slid over each other.
48
why is graphite a good conductor of electricity and heat?
Since each carbon atom is bonded to three other carbon atoms, they still have one electron left in the outer-energy level. This electron becomes delocalised. The delocalised electrons can move between layers, this means they can conduct thermal energy and electricity.
49
In diamond each carbon atom is connected to ...
four other carbon atoms
50
In graphite each carbon atom is connected to ...
three other carbon atoms
51
Graphene is a single layer of ...
graphite
52
graphene is how many atoms thck?
one
53
What are the properties of graphene?
excellent conductor of electricity and heat
extremely strong
54
Why is graphene a good conductor of electricity and heat?
each carbon atom is bonded to three other carbon atoms, so each atom will still have one electron in its outer-shell left, this electron becomes delocalised. The delocalised electrons can act as charge carriers and can conduct thermal energy
55
Why is graphene extremely strong?
it has many very strong covalent bonds and no weak intermolecular forces
56
What are fullerenes?
Fullerenes are molecules of carbon atoms with hollow shapes
57
The first fullerene discovered was the buckminsterfullerene, also known as ...
the buckyball
58
How many carbon atoms are in a buckminsterfullerene (buckyball)?
60
59
What shape does a buckyball look like?
a football
60
What can fullerenes be used for?
pharmaceutical delivery, lubricants, catalysts
61
Carbon nanotubes are fullerenes shape into ...
long cyclinders
62
Carbon nanotubes have high tensile strength meaning ...
that they can be stretched without breaking
63
Why are carbon nanotubes excellent conductors of electricity?
they have delocalised electrons, which can act as charge carriers
64
What can carbon nanotubes be used for?
to reinforce materials e.g high quality sporting equipment like tennis rackets
65
How are polymers made?
polymers are made from small identical molecules (monomers) that join together to form a very long chain.
66
What diagram is used for polymers?
Repating Unit
67
Why does the covalent bonds on repeating unit diagrams extend outside the brackets?
It shows that the polymer molecule extends in both directions
68
What does the n represent in the repeating unit diagrams?
n represents a large number of repeating units, which would join together to form the polymer
69
Why are most polymers solid at room temperature?
because the intermolecular forces of attraction between polymer molecules are relatively strong. It takes a lot of energy to break these forces
70
How are the atoms arranged in a metal?
in regular layers
71
in metals the electrons in the outer-energy level of each atom are ...
delocliased
72
Explain the attraction in metals
there is a strong electrostatic attraction between the negative sea of delocalised electrons and the positive metal ions.
73
metallic bonding is when ..
a metal reacts with the same type of metal
74
what do metallic compounds form?
giant metallic lattices
75
during metallic bonding ...
the outer-shell electrons of each of the metal atoms become delocalised, forming a sea of delocalised electrons
this leads a strong electrostatic attraction between the positive metal ions and the delocalised electrons
76
explain the structure of a giant metallic lattice
A giant metallic lattice contains metal cations surrounded by a sea of delocalised electrons
77
What are the properties of metal lattices?
high melting and boiling point
excellent conductors of heat and electricity
can be bent and shaped
78
why do giant metallic lattices have a high melting and boiling point?
because a great deal of energy is required to break the strong metallic bonds
79
why are metallic lattices good conductors of heat and electricity?
the delocalised electrons can move through-out the structure of the lattice, so they can act as charge-carriers, carrying a electrical current or thermal energy.
80
why can metal be bent and shaped?
In metals, the layers of atoms can slide over each other, since the structure is in regular layers, where the ions are all the same sized.
This means pure metals are not hard enough to be useful
81
what is an alloy?
a mixture of metals
82
why are alloys harder than pure metals?
the different sized atoms in alloys distorts the layers, making it more difficult for them to slide over each other.
83
1mm in m
1mm = 1 x 10^-3 m
84
1 micrometer in m
1u in m
1u = 1 x 10^-6 m
85
1 nanometer in m
1nm in m
1nm = 1 x 10^-9
86
coarse particles are often referred to as ...
dust
87
which PM are coarse particles?
10
88
coarse particles have a diameter between ...
1 x 10^-5 m and 2.5 x 10^-6m
89
which PM are fine particles?
2.5
90
fine particles have a diameter between ...
100 - 2500 nm
1 x 10^-7m and 2.5 x 10^-6m
91
nanoparticles have a diameter between ...
1 - 100 nm
92
how many particles are in nanoparticles?
a few hundred
93
as the particles size decrease by 10 times, the SA to V ration increases by ...
10 times
94
nanoparticles have a huge ...
SA to V ratio
so even a small amount of nanoparticles has a massive SA
95
how does the amount of nanoparticles needed compare to materials with normal particles size
a much smaller quantity of nanoparticles is needed, since they have a higher SA:V
96
nanoparticles are used in ...
medicine, suncreams, cosmetics, deodorants, electronics and catalysts
97
what is the risk of nanoparticles?
nanoparticles can be absorbed into the body and can enter our cells
no one knows the long term effect of this, so nanoparticles need to be studied more carefully
some nanoparticles are toxic
98
advantage of a dot and cross diagram (simple covalent molecules)
because we use dots to represent electrons from one atom, and crosses to represent electrons from another element,
it is very clear to see where the electrons are coming from
99
disadvantage of a dot and cross diagram (simple covalent molecules)
it does not show us the shape of the molecule
100
disadvantages of a stick diagram (simple covalent molecules)
it does not show which electron in the bond came from which atom
it gives us no idea of the outer electrons that are not in bonds
101
advantage of a 3 dimensional stick diagram (simple covalent molecules)
it shows the shape of the molecule
102
advantage of a ball and stick diagram (giant ionic lattices)
it allows us to clearly see the ions in 3 dimensions
103
disadvantages of a ball and stick diagram (giant ionic lattices)
it shows the ions as widely spaced when in reality the ions are packed closely together
it only shows a tiny part of the giant crystal lattice, it gives a mistaken impression of the size of the structure
104
advantage of a space filling diagram (giant ionic lattices)
it gives a better idea of how closely packed the ions are
105
disadvantage of a space filling diagram (giant ionic lattices)
it can be difficult to see the 3 dimensional packing
