Topic 2 Bonding, Structure And Properties Of Mass Flashcards
(124 cards)
1
Q
What is a gas like?
4 points
A
- Particles are free to move
- State symbol= g
- Can be easily compressed
- expand to fill the shape of the container
2
Q
What is a liquid like?
3 points
A
- Particles can flow over each other but are still attracted to each other.
- Changes shape in different containers.
- State symbol= l
3
Q
What is a solid like?
3 points
A
- Particles are fixed in place
- Fixed shape and volume
- State symbol= s
4
Q
What are the limitations of the particle model?
A
- Not all particles are the same size
- Not all particles are round
- Particles are not solid
5
Q
What are ions?
A
Charge particles
6
Q
When are ions formed?
A
When atoms lose or gain electrons to form ions to try and get a full outer shell of electrons to become stable.
7
Q
What do metals do with electrons?
A
Lose them to become positive ions.
8
Q
What do non-metals do with electrons?
A
Gain them and become negative ions
9
Q
How are the number of electrons lost/gained and the charge relative?
A
The number of electrons lost or gained is the same as the charge.
E.g.
2 lost electrons= 2+
3 gained electrons= 3-
10
Q
Which groups of elements are most readily to form ions?
A
1, 2, 6, 7
11
Q
How is an ionic bond made?
A
By the transfer of electrons between a metal and a non-metal.
12
Q
What happens when a metal and a non-metal react together?
A
The mental loses electrons to become positively charged and the non-metal gains electrons to become negatively charged.
13
Q
How are the oppositely charged ions in an ionic bond held together?
A
Strongly but electrostatic forces.
14
Q
What sort of diagrams should you use to represent ionic bonds?
A
Dot and cross diagrams
15
Q
How do you work out the empirical formula of a dot and cross diagram?
A
Count up how many atoms there are of each element and balance them out.
16
Q
How do you work out the empirical formula using a 3D diagram of an ionic lattice?
A
Use it to work out what ions are in the ionic compound.
17
Q
What sort of structure do ionic compounds have?
A
A structure called a giant lattice.
18
Q
What is a giant lattice?
A
A 3D structure made by oppositely charged ions held together by electrostatic forces in all directions.
19
Q
Why are giant lattices in a 3D shape?
A
Because there is an attraction between every opposite ion.
20
Q
What are the properties of ionic compounds?
A
High melting point- to break strong electrostatic forces.
Soluble
Conduct electricity when dissolved in a solution or molten as ions are free to move and carry electric current.
21
Q
Why are dot and cross diagrams useful for showing ionic compounds?
A
They show how they are formed.
22
Q
Why are dot and cross diagrams not useful for showing ionic compounds?
A
They don’t show the structure of the compound, the size of the ions or how they are arranged.
23
Q
When is a covalent bond formed?
A
When non-metal atoms bond together, they share pairs of electrons to make covalent bonds.
24
Q
What is a covalent bond like?
A
The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by strong electrostatic forces, making the covalent bond very strong.
25
What is a positive of writing the empirical formula for a covalent bond?
It can be written easily and is easy to understand.
26
Why are dit and cross diagrams useful for showing covalent bonds?
They are useful for showing which atoms the electrons in covalent bond comes from.
27
Why are diagrams such as:
O-H-O
Good for showing covalent bonds?
They show how atoms are connected in large molecules.
28
Why are diagrams such as:
O-H-O
Bad for showing covalent bonds?
They don’t show the 3D structure of the molecule or which atoms the electrons in the covalent bonds have come from.
29
What does the 3D model show of covalent bonds?
The atoms, the covalent bonds and their arrangement.
30
Why can 3D models showing covalent bonds get confusing?
When there are lots of atoms to include.
| They also don’t show where the electrons in the bonds have come from.
31
What are simple molecular substances?
Substances made up of molecules containing a few atoms joined together by covalent bonds.
32
What are the properties of simple molecular substances (simple covalent molecules)?
(7)
- Have simple molecular structures
- Held together by very strong covalent bonds but the forces between the molecules are very weak.
- The melting and boiling points of simple molecular substance are very low because you need to break the (weak) intermolecular forces, not the (strong) covalent bonds.
- Most are liquids or gases at room temperature
- As molecules get bigger the strength of the intermolecular forces increase, so more energy is needed to break them.
- Don’t conduct electricity because there is no charge and all electrons are used in bonding so there are no free electrons
- usually soft and brittle
33
What are polymers?
Long chains of repeating units. In a polymer lots of small units are linked together to form a long polymer that has repeating units.
34
How are all the atoms in a polymer joined?
Be strong covalent bonds.
35
How can you draw a polymer easily?
You can draw out the shortest repeating section, called the repeating unit.
36
How do you find the molecular formula of a polymer?
Write down the molecular format of the repeating units in brackets and put an ‘n’ outside.
37
What are the intermolecular forces between polymer molecules like?
They are larger than the intermolecular forces between covalent molecules. This means most polymers are solid at room temperature. The intermolecular forces are still weaker than ionic or covalent bonds so they generally have lower boiling points than ionic or giant molecular compounds.
38
What are polymers, simple molecular substances and giant covalent structures held together by?
Covalent bonds
39
What sort of molecules are giant covalent structures held together by?
Macromolecules
40
What are the properties of giant covalent structures?
- All atoms bonded by strong covalent bonds.
- Very high melting and boiling points as lots of energy is needed to break covalent bonds.
- Usually do not conduct electricity (no charged particles and no free electrons)
41
What are the main examples of giant covalent structures?
Diamond, Graphite, Silicon dioxide
42
What is the structure of diamond like?
Each carbon atom forms four covalent bonds in a very ridged covalent structure.
43
What is the structure of graphite like?
Each carbon atom forms three covalent bonds to create layers of hexagons. Each carbon also has one delocalised electron.
44
What is the structure of silicon dioxide like?
Sometimes called silica, this is what sand is made of. Each grain of sand is one giant structure of silicon and oxygen.
45
What are allotropes?
Different structural forms of the same element in the same physical state.
46
What is diamond made up of?
Carbon atoms that form four covalent bonds as there are four electrons in its outer shell) this makes diamond very hard.
47
Why does diamond have a very high boiling point?
The covalent bonds are very strong.
48
Why does diamond not conduct electricity?
No free electrons
49
What is graphene?
A sheet of carbon atoms joined in hexagons (one layer of graphite).
50
Why are layers of graphene free to move over each other?
There are no covalent bonds between layers.
51
Why is graphite ideal as a lubricant?
The layer of graphene are held together weakly so they’re free to move over each other. This makes graphite soft and slippery.
52
Why does graphite have a high melting point?
Covalent bonds in layers need lots of energy to break.
53
Why can graphite conduct electricity and thermal energy?
Only three out of each carbon’s four outer electrons are used in bonds, so each carbon has one electron that’s delocalised so graphite conducts electricity and thermal energy.
54
What is the thickness of graphene like?
One sheet is one atom thick so it is a 2D compound.
55
Why can graphene be added to composite materials to make them stronger?
A network of covalent bonds makes graphene very strong and very light so it can be added to composite materials to improve their strength without adding much weight.
56
What are the properties of diamond?
- Colourless
- Used in jewellery
- Lustrous
- Doesn’t conduct electricity
- insoluble in water
- Hard
- Transparent
- High melting point
- Used in cutting tools
57
What are the properties of graphite?
- Black
- Conducts electricity
- slippery
- opaque (as you have lots of layers together)
- used as electrodes
- Used as pencil leads
- inflexible
- brittle
58
What are the properties of graphene?
- 2D
- thin
- flexible
- strong
- non flammable
- transparent
- conductive
59
What are fullerenes?
Molecules of carbon shaped like closed tubes or hollow balls.
60
How are fullerenes arranged?
In hexagons but can also contain pentagons or heptagons.
61
What is buckminsterfullerene?
The first fullerene to be discovered. It’s got the molecular formulae of C60 and forms a hollow sphere containing 20 hexagons and 12 pentagons.
62
What can fullerenes be used to do?
To ‘cage’ other molecules.
63
How do fullerenes ‘cage’ other molecules?
The fullerene structure forms around another atom or molecule which is then trapped inside.
64
Why do fullerenes make great industrial catalysts?
They have a large surface area. Individual catalyst molecules could be attached to the fullerene.
65
What can fullerenes form?
Nanotubes (tiny carbon cylinders)
66
What is the ration between high in nanotubes?
The length and diameter
67
What is the strength of nanotubes like?
They have a high tensile strength.
68
What can nanotubes conduct?
Both electricity and thermal energy.
69
What can nanotubes be used for?
In electricity or to strengthen materials.
70
What sort of structure do metals have?
A giant structure.
71
What are the electrons in the outer shell of metals like?
They are delocalised.
72
What sort of forces of attraction are there in a metal?
Forces of electrostatic attraction between the positive metal ions and the shared negative electrons. These forces of attraction hold the atoms together in a regular structure and are known as metal mix bonding.
73
What is the strength of metallic bonding like?
Very strong.
74
Why are metals solid at room temperature?
Because the electrostatic forces between the metal atom and the delocalised sea of electrons are very strong, so need lots of energy to be broken.
75
Why are metals good conductors of electricity and heat?
The delocalised electrons carry heat/ current through the whole structure.
76
Why are pure metals elements?
Because all the atoms are exactly the same shape and size.
77
What happens if you apply force to a pure metal?
The electrons easily slide over each other, this is why metals can be bent and beaten into shape- they’re malleable.
78
What is an alloy?
A mixture of two different types of metal. This means that there are two or more different types of atoms in an alloy. These different atoms are different sizes.
79
Why are alloys described as mixtures rather than compounds?
They aren’t chemically bonded.
80
What are the layers of atoms in alloys like?
They are distorted.
81
Why are alloys harder and more difficult to bend than pure metals?
The different sized atoms are difficult to push over each other.
82
What are the diameters of coarse particles like?
2500nm-10000nm
| 2.5 x 10^-6m - 1 x 10^-5
83
What are the diameters of fine particles like?
100nm - 2500nm
| 1 x 10^-7m - 2.5 x10^-6
84
What are the diameters of nanoparticles like?
1nm- 100nm
| 1 x 10^-9 m - 1 x 10^-7m
85
How do you work out surface area to volume ratio?
Surface area/ volume
86
What can the surface area to volume ratio of a particle do?
Affect the way it behaves.
87
As particles decrease in size what happens to their surface area?
Their surface area increases in relation to their volume, this cause the surface area to volume ratio to increase.
88
What is the surface area to volume ratio of a nano particle like?
It’s very high (the surface area is large compared to the volume).
89
How are nano particles used in fabrics?
Silver nano particles are embedded in fabrics and used in sports equipment such as tennis rackets.
90
What are the benefits of using nano particles in fabrics?
- Incredibly strong but light
| - Give fabrics antibacterial properties
91
What are the potential disadvantages of using nano particles in fabrics?
- Increases risk of nano particles entering the environment, they wash out of fabric into the environment.
92
How are nano particles used in medicine?
Nano cages of gold deliver drugs to where they need to go in the body.
93
What are the benefits of using nano particles in medicine?
- Tumour cells can be destroyed without damaging healthy ones.
94
What are the potential disadvantages of using nano particles in medicine?
- Could have unpredictable results on cells
| - New technology may need further testing
95
How are nano particles used in electronics?
- To improve display screens
- Used to inhibit the growth of micro organisms
- being developed into very small circuits.
96
What are the benefits of using nano particles in electronics?
- Make highly sensitive sensors
| - Reduced power consumption weight
97
What are the potential disadvantages of using nano particles in electronics?
Risk of them finding their way into the atmosphere
98
How are nano particles used in cosmetics?
Can work deeper in the skin and are cared in zinc oxide.
99
What are the benefits of using nano particles in cosmetics?
- UV protection
- Deeper skin penetration
- Improved hydration
- Allows the packaging of ingredients in non-soluble packets
100
What are the potential disadvantages of using nano particles in cosmetics?
- Nanotitanium can be absorbed through the skin
| - can easily be inhaled and swallowed in cosmetics
101
How are nano particles used in sun creams?
Nano particles work as UV filters. Titanium dioxide and zinc oxide are the main compounds used in these applications.
102
What are the benefits of using nano particles in sun creams?
- Blocks UV filters
- Absorb light
- Give a much better performance than larger particles
103
What are the potential disadvantages of using nano particles in sun creams?
Titanium and zinc oxide can damage DNA and cell function by the production of free radicals when exposed to light.
104
How can nano particles be used in catalysts?
Platinum nano particles used as catalysts in fuel cells that produce hydrogen ions. Large surface area make then very effective as catalysts.
105
What are the benefits of using nano particles in catalysts?
They are able to increase the rate of chemical reactions.
106
What are the potential disadvantages of using nano particles in catalysts?
If a spark is made near a large quantity of the catalyst there could be a violent explosion.
107
How are nano particles used in fabrics?
Silver nano particles are embedded in fabrics and used in sports equipment such as tennis rackets.
108
What are the benefits of using nano particles in fabrics?
- Incredibly strong but light
| - Give fabrics antibacterial properties
109
What are the potential disadvantages of using nano particles in fabrics?
- Increases risk of nano particles entering the environment, they wash out of fabric into the environment.
110
How are nano particles used in medicine?
Nano cages of gold deliver drugs to where they need to go in the body.
111
What are the benefits of using nano particles in medicine?
- Tumour cells can be destroyed without damaging healthy ones.
112
What are the potential disadvantages of using nano particles in medicine?
- Could have unpredictable results on cells
| - New technology may need further testing
113
How are nano particles used in electronics?
- To improve display screens
- Used to inhibit the growth of micro organisms
- being developed into very small circuits.
114
What are the benefits of using nano particles in electronics?
- Make highly sensitive sensors
| - Reduced power consumption weight
115
What are the potential disadvantages of using nano particles in electronics?
Risk of them finding their way into the atmosphere
116
How are nano particles used in cosmetics?
Can work deeper in the skin and are cared in zinc oxide.
117
What are the benefits of using nano particles in cosmetics?
- UV protection
- Deeper skin penetration
- Improved hydration
- Allows the packaging of ingredients in non-soluble packets
118
What are the potential disadvantages of using nano particles in cosmetics?
- Nanotitanium can be absorbed through the skin
| - can easily be inhaled and swallowed in cosmetics
119
How are nano particles used in sun creams?
Nano particles work as UV filters. Titanium dioxide and zinc oxide are the main compounds used in these applications.
120
What are the benefits of using nano particles in sun creams?
- Blocks UV filters
- Absorb light
- Give a much better performance than larger particles
121
What are the potential disadvantages of using nano particles in sun creams?
Titanium and zinc oxide can damage DNA and cell function by the production of free radicals when exposed to light.
122
How can nano particles be used in catalysts?
Platinum nano particles used as catalysts in fuel cells that produce hydrogen ions. Large surface area make then very effective as catalysts.
123
What are the benefits of using nano particles in catalysts?
They are able to increase the rate of chemical reactions.
124
What are the potential disadvantages of using nano particles in catalysts?
If a spark is made near a large quantity of the catalyst there could be a violent explosion.
