Types of Substance - Topic 1 Flashcards
1
Q
Describe the appearance of metals:
A
- Metallic
- Shiny
2
Q
Describe the melting and boiling points of metals:
A
- High boiling point
- High melting point
3
Q
Describe the strength of metals:
A
- Strong
- Malleable
4
Q
What is the physical state of metals at room temp?
A
- Solid
- mercury is an exception
5
Q
Malleability:
A
ability to be bent into different shapes
6
Q
Describe the malleability of metals:
A
Malleable
7
Q
Ductility:
A
ability to be drawn into wires
8
Q
Describe the ductility of metals:
A
Ductile
9
Q
Describe the electrical conductivity of metals:
A
Good conductors of electricity
10
Q
Describe the appearance of non-metals:
A
Dull
11
Q
Describe the melting and boiling points of non-metals:
A
- Low melting point
- Low boiling point
12
Q
Describe the strength of non-metals:
A
Weak
13
Q
Describe the malleability of non-metals:
A
Brittle
14
Q
Describe the ductility of non-metals:
A
Not ductile
15
Q
Describe the electrical conductivity of non-metals and what is the exception:
A
- Poor conductors of electricity
- Graphite is an exception
16
Q
Describe the thermal conductivity of non-metals:
A
Poor conductors of heat
17
Q
Describe the density of metals:
A
have a high density
18
Q
Properties of ionic compounds class practical: What is the apparatus needed?
A
- beakers
- compounds from table
- spatulas
- equipment to make a circuit
- glass rod
- test tube
19
Q
Properties of ionic compounds class practical: Method
A
- Describe the appearance of all the compounds.
- Put a spatula of magnesium oxide into a test tube and heat for one minute at the tip of a blue flame. This is the hottest part of the flame. (it doesn’t melt showing that magnesium oxide has a high melting point)
- Add a few spatulas of the solid to a small beaker, construct a circuit to test the conductivity of the solid.
- Add 20-30 mls of water to the solid. Does it dissolve? Stir with a glass rod to help.
- Construct a circuit to test the conductivity of the solution if the compound dissolves.
20
Q
Why does magnesium oxide have a higher melting point than sodium chloride?
A
- The higher the charges of the ion the stronger the bonding (due to stronger electrostatic forces of attraction between them)
- The stronger the bonding the more energy needed to break the bonds
21
Q
What two materials are ionic compounds formed between?
A
metal and a non-mental
22
Q
What do metals do to obtain full outer shells and what do non-metals do to obtain all outer shells?
A
- in general metals lose electrons to obtain a full outer shell of electrons like a noble gas
- non-metals gain electrons to get a full outer shell
23
Q
What type of ions do metals form and what type of ions do non-metals form?
A
- in general, metals form positive ions - cations
- non-metals form negative ions - anions
24
Q
How are ionic compounds formed?
A
ionic compounds are formed by the transfer of electrons between atoms to produce cations and anions
25
What do ionic compounds look like?
ionic compounds and solutions of group 1 and 2 are white powders and ionic compounds that have transition metals are different colours
26
Describe the structure of ionic compounds:
- between a metal and non-metal
- positive and negative ions (oppositely charged ions) are held tightly/close together by strong electrostatic forces of attraction in all directions between oppositely charged ions in a giant regular lattice structure - these forces are called ionic bonds
- consists of a regular arrangement of ions
27
What is the bp and mp of ionic compounds like?
high melting points and boiling points due to their being strong bonds between the ions (caused by strong forces of electrostatic attraction) requiring a lot of energy to be overcome so have high mp’s and bp’s
28
Do ionic compounds conduct electricity as solids?
- Ionic compounds will not conduct electricity as solids - due to the fact that ions are not free to move through solid structure as all the charged ions are arranged in a fixed position in a lattice so cannot conduct electricity despite being charged particles as they are not free to move
- despite having charged particles (ions) due to the regular arrangement of the ions in a lattice and the ions are held together by strong ionic bonds (strong electrostatic forces of attraction) between oppositely charged ions so the ions are closely packed together and so when an ionic compound is solid it can't conduct electricity as the ions can't move
29
Do ionic compounds conduct electricity as liquids (when molten or in aqueous solution)?
- ionic compounds do conduct electricity as liquids when in an aqueous solution as the ions can move and carry charge as the ions are surrounded by water molecules causing the lattice to be broken down (popped apart) (and the water cuts down the forces between the ions) so the ions become separated allowing the ions to be able to move and carry current/charge
- ionic compounds do conduct electricity when molten as the heat energy overcomes the strong ionic bonds (strong electrostatic forces of attraction) between oppositely charged ions which allows the ions to move freely so therefore ionic compounds conduct electricity when molten
30
Are ionic compounds heat compounds?
no ionic compounds are not heat compounds as ions aren't free to move as they are in a fixed lattice when solid
31
Are ionic compounds soluble?
- they are generally soluble in water as the ions are surrounded by water molecules and the lattice is popped apart
- they often dissolve in water to form an aqueous solution
32
How strong are ionic compounds?
they are hard but brittle as when a layer of atoms is moved the layers repel each other and the object shatters
33
Describe the structure of simple covalent substances:
- non-metal + non-metal
- molecules that consist of just a few atoms held together by covalent bonds
- these molecules are bonded together by a shared pair of electrons, which forms the strong covalent bond
- between molecules, weak intermolecular forces hold the molecules in either a solid, liquid or gaseous arrangement
34
What are the mp and bp of simple covalent compounds like?
- mp and bp points are low - many are either liquids or gases at room temperature
- to melt//boil a simple covalent bond you only need to break the intermolecular forces between molecules which are weak so require less energy to break so covalent compounds have low mp’s and bp’s
35
Do simple covalent compounds conduct electricity?
- no because it is simple covalent and simple covalent compounds exist as molecules
- electrical conductivity is low/poor as for a substance to conduct electricity the substance has to have charged particles that are free to move (free electrons) - molecules are neutral
- Substances that consist of small molecules don’t conduct electricity, because small molecules do not have an overall electric charge
36
Do simple covalent compounds conduct electricity as a solution?
- Substances that consist of small molecules don’t conduct electricity, because small molecules do not have an overall electric charge
- Although, some breakdown in water to form ions which can conduct electricity
37
Are simple covalent compounds soluble?
- many are insoluble in water, but some are soluble because they can form intermolecular forces with water which are stronger than those between water molecules or their own molecules already (e.g. CO2 and NH3 are soluble)
- solubility in water is variable
- oxygen dissolved in water, ammonia dissolves in water, methane dissolves in water, HCl dissolves in water
- substances chemically similar to water dissolve in water
38
Describe the general structure of giant covalent structures:
- non-metal + non-metal
- a three-dimensional structure of atoms that are joined by covalent bonds
39
What is the mp/bp of giant covalent structures like?
very high mp and bp due to strong covalent bonds between the carbon atoms which require a lot of energy to be overcome
40
Are giant covalent compounds soluble?
-
They are Insoluble in water as giant covalent substances cannot form these strong attractions with water, so they are insoluble as all the electrons are held tightly between the atoms, and aren't free to move
41
Do giant covalent structures conduct electricity?
- most substances with giant covalent structures have no charged particles that are free to move - this means that most cannot conduct electricity
- graphite, a form of carbon which can conduct electricity as it has delocalised electrons which carry charge and can move which are found between the layers of the graphite
42
Describe the structure of metallic bonding:
- atoms in a metal are held together by metallic bonding and are arranged in a regular pattern (lattice) and are closely packed together.
- in a metallic structure positive metal ions (consisting of the nucleus and inner shell electrons) are held together by the outer shell electrons which become delocalised (ie no attached to one particular atom and with a certain freedom to move)
- electrostatic forces if attraction between the positive metal ions (cation) and the delocalised electrons
- all metal have positive charges
- there are no non-metals to give the extra electron to so instead the electrons are removed from the atoms outer shell and then float in between the cations - so the delocalised electrons are free to move through the whole structure
- the higher the charge on the metal and the more delocalised electrons found in between the cations the stronger the bonding also the sharing of delocalised electrons gives rise to strong metallic bonds
- number of delocalised electrons tells us which group the metallic structure is in
- if the temperature increases the ions will vibrate on the spot due to having more energy
43
What is the mp and bp of metals like?
high mp’s and bp’s as there are strong electrostatic forces of attraction in metallic bonds between positive ions and delocalised electrons
44
Can metals conduct heat?
- metals can conduct heat do you to having delocalised electrons that are free to move through the metallic structure
- the delocalised electrons are given kinetic energy which means they can move through the lattice randomly and knock into ions and so can provide heat energy to ions o the other side of the lattice much faster
45
Can metals conduct electricity?
metals are good conductors of electricity as they have delocalised electrons that can carry charge and move through the lattice
46
How strong are metals?
- metals are malleable and ductile
- metals are ductile and malleable as the layers of atoms in metals can slide over each other without bonding being affected and without breaking any bonds (due to delocalised electrons) - graphite (giant covalent structure) graphite can conduct electricity for the same reason
47
Are metals soluble?
metals are insoluble due to the strong electrostatic forces of attraction between the delocalised electron and the cations in the lattice - however some metals may react with water
48
Alloys:
mixtures of metals where the different metals are metallically bonded together in a giant metal lattice e.g. bronze, stainless steel
49
Why aren't alloys regarded as compounds?
not a compound as there aren't a fixed ratio of atoms of each type of elements in the lattice
50
Why are alloys generally tougher and stronger than pure metals?
in pure metal layers can slide over each other (which makes them malleable) but it can't in an alloy due to different sized atoms
51
What is the alloy stainless steel made up of?
- iron
- chromium
- manganese
- carbon
52
What is the alloy bronze made up of?
- copper
- tin
53
What is the alloy electrum made up of?
- gold
- silver
54
What is the alloy brass made up of?
- copper
- zinc
55
What is the alloy steel made up of?
- iron
- carbon
- others
56
Class experiment to compare the physical properties of different substances: Apparatus needed:
- ignition tubes
- peg
- Bunsen burner
- mat
- boiling tube
- bung
- small beaker
- wires
- power pack / batteries
- light bulb
- crocodile clips
- 2 graphite electrodes
- electrode holder
- substances to be tested
- eye protection
57
Class experiment to compare the physical properties of different substances: Safety guidance
- wear eye protection e.g. safety goggles
- keep thumb on bug when's taking the boiling tube
- ignition tube will be very hot
- substances B, D and E are very flammable - just heat a small amount in ignition tubes and stop heating once it melts
58
Class experiment to compare the physical properties of different substances: Method
1. Place a small spatula load of the substances into an ignition tube. You should heat it in a Bunsen flam until it melts. Do not heat for more than 2mins. Then put the hot tube on the mat and leaf it to cool own.
2. In the results table describe the melting point as either low, high or very high.
3. Place one spatula load of the substance in a boiling tube and add some water so that it is about half full. Place a bung on the tube and shake it to try and dissolve the solid.Record the results in the table.
4. If the substance dissolves in water, pour it into a smaller beaker. Set up a circuit at the side. Test to see if the solution conduct electricity by seeing if the light bulb lights up (you only need to have the circuit connected for a few seconds to see). Record the results in the table.
5. With the large solid piece of each substance test to see if it conducts electricity. Record the results in the table.
6. Decide what type of structure the substance has.
7. Test the other substances in the same way to find their structure.
59
How are diamond and graphite similar?
- both different forms of the same element - carbon (allotropes)
- giant covalent substances
60
How are the structures of diamond and graphite similar?
both structures contain many thousands of carbon atoms joined together by strong covalent bonds
61
Why are the structures of diamond and graphite different despite being made up of the same atoms?
the structure in which the carbon atoms are arranged and the bonding of the carbon atoms are different results in different physical properties
62
Describe the structure of diamond:
- tetrahedral lattice
- a giant covalent structure made up of carbon atoms each of which form four covalent bonds with other four carbon atoms
- carbon atoms form a regular tetrahedral network structure
- no delocalised (free) electrons that are free to move
63
What is the mp and bp of diamond like?
very high mp and bp due to strong covalent bonds between the carbon atoms which require a lot of energy to be overcome
64
Describe the hardness of diamond:
very hard due to rigid network of carbon atoms and strong covalent bonds
65
Does diamond conduct electricity?
- has no delocalised (free) electrons that can move and carry charge
- all carbon atoms are bonded to other carbon atoms - all valence electrons are bonded
66
What are the industrial uses of diamond and why?
Used as a cutting tool, drilling tool, abrasive etc. as it is very hard, due to its rigid structure because of its strong covalent bonds as each carbon atom has 4 bonds
67
Describe the structure of graphite:
- infinite lattice of hexagons
- a giant covalent structure which is made up of carbon atoms each of which form 3 covalent bonds with three other carbon atoms
- the atoms form layers of hexagonal rings which have no covalent bonds between them
- each carbon atom has 3 covalent bonds to other carbon atoms (but it wants 4 like carbon) forming layers of hexagonal rings, which have no covalent bonds between the layers - the spare delocalised electron sits between the sheets
- there is one delocalised electron per carbon atom which is free to move to carry charge
- one layer = graphene
- multiple layers = graphite
- layers of graphite aren't well connected as the forces between the layers are weak - weak forces hold the layers of carbon atoms together
- one layer is strong as there are strong bonds between carbons atoms in a layer
- the extra electron makes a weak bond to the adjacent layers
- sheets are attracted to electrons which are attracted to the sheet which is attracted to the electrons through electrostatic forces of attraction
68
What is the mp and bp of graphite like?
very high mp and bp due to strong covalent bonds between the carbon atoms which require a lot of energy to be overcome
69
Describe the hardness of graphite:
Graphite is soft and slippery as the layers can slide over each other due to there being no covalent bonds between the layers, but weak intermolecular forces that the delocalised electrons provide to the adjacent layers
70
Does graphite conduct electricity?
can conduct electricity - has delocalised electrons between sheets (layers) of carbon toms that are free to move and can carry charge
71
What are the industrial uses of graphite and why?
- useful as a lubricant as there are weak intermolecular forces and there are no covalent bonds between the layers (weak forces between the layers) meaning the sheets can slide over each other
- Electrodes as graphite can conduct electricity unlike diamond
72
Diamond:
a giant covalent structure made up of carbon atoms each of which form four covalent bonds with other four carbon atoms
73
Graphite:
- a giant covalent structure which is made up of carbon atoms each of which form 3 covalent bonds with three other carbon atoms
- the atoms form layers of hexagonal rings which have no covalent bonds between them
- there is one delocalised electron per carbon atom which is free to move to carry charge
74
Graphene:
a single layer of graphite with properties that make it useful in electronics and composites
75
Lattice:
- a repeating regular arrangement of atoms/ions/molecules
- this arrangement occurs in crystal structures
76
Electrostatic forces:
the strong forces of attraction between oppositely charged ions
77
Simple molecules:
molecules containing a fixed number of atoms covalently bonded together
78
Giant covalent molecule:
molecules containing many atoms covalently bonded together
79
Metallic bond:
the bonds present in metals between positive metal ions (cations) and negatively charged electrons
80
Conductor:
A material that contains charged particles which are free to move to carry electrical or thermal energy
81
Ionic bond:
the bond formed between the oppositely charged ions when a metal atom loses electron(s) to form a positively charged ion and a non-metal gains these electron(s) to form a negatively charged ion
82
Ionic compound:
chemical compound formed of oppositely charged ions held together by string electrostatic forces of attraction
83
What is graphene?
- a single layer of graphite and is just one atom thick
- essentially a 2 dimensional structure
84
Uses of graphene:
- is an electrical conductor at RTP (room temperature and pressure) and has very low electrical resistance - means it could be used to make super fast electrical components and computer parts
- it is the stronger known substance - so could be used to make strong and lightweight carbon material
- it is also an excellent thermal conductor, transparent and elastic
85
Diagram of graphene:
86
What are fullerenes?
- allotropes of carbon
- they are 3D hollow shapes made of carbon
87
What was the first fullerene discovered?
Buckminster fullerene which is made up of 60 carbon atoms joined together to make a sphere - C60
88
What is the mp and bp of Buckminster fullerene like?
- Buckminster fullerene (C60) is a single molecular structure and has weak intermolecular forces between the C60 molecules
- to melt or boil a fullerene not much energy is needed to overcome only these weak forces (no covalent bonds are broken)
- therefore, the melting points of fullerenes are much lower than of graphite and diamond
89
Uses of fullerenes:
- to deliver drugs in the body
- as lubricants
- as catalysts
- they can act as hollow cages to trap other molecules which is how they can carry drug molecules around the body and trap harmful chemicals
90
Diagram of Buckminster fullerene:
91
What are carbon nanotubes?
carbon nanotubes are cylindrical fullerenes
92
Properties of carbon nanotubes:
- very strong
- very good conductors of electricity
93
Uses of carbon nanotubes:
- used as semi-conductors in electrical circuits - as it is a very good conductor of electricity
- used as catalysts - catalysts are often attached to nanotubes since nanotubes have a large surface area - this means that there is more chance the reactants will collide with the catalyst - larger area for collision which helps increase the rate of reaction
- used for reinforcing materials e.g. tennis rackets - as it is very strong
94
Diagram of carbon nanotubes:
95
What do simple polymers consist of?
- simple polymers consist of large molecules containing chains of atoms
- very long chain like molecules
- e.g. poly(ethene)
96
Describe the structure of polymers:
- the atoms in the polymer chains are linked to each other by strong covalent bonds i.e. the intramolecular/internal molecular forces between atoms in polymer chains are strong
- the forces between polymer chains are weaker i.e. weaker intermolecular forces
- however, the intermolecular forces between the polymer chains are still strong enough to ensure that all polymers are solid at room temperature
97
How can the strength of the intermolecular forces between the polymer chains affect their properties?
- in some polymers the intermolecular forces between the polymer chains are relatively weak
- these polymers have a low melting point is little energy is needed to overcome the intermolecular forces between the polymer chains
- these polymers are also flexible since the polymer chains can move over each other due to the weak intermolecular forces between the polymer chains
- an example of such polymer is plastic which consists of long chains of carbon atoms (1000s of carbon atoms long) with two hydrogen atoms joined to each carbon atom
- the weaker intermolecular forces between polymer chains in polythene make it flexible and an ideal material for polythene bags
- other polymers have much stronger intermolecular forces between polymer chain (or even covalent cross links)
- these polymers have a much higher melting point due to more energy being needed to overcome the stronger intermolecular forces between the polymer chains
- these polymers are also rigid as the polymer chains cannot move over each other due to the stronger intermolecular forces between the polymer chains
98
Diagram of polymers:
99
Metallic bond:
the bonds present in metals between positive metal ions (cations) and negatively charged electrons
100
Dot and cross diagram for ionic bonding example:
101
What does a dot and cross diagram for ionic bonding show?
- nucleus
- elements of the atoms/ions
- atomic structure - inc. electronic configuration
102
Limitations of a dot and cross diagram for ionic bonding:
- doesn't show 3D structure
- doesn't show bonds between atoms/ions
103
2D ball and stick for ionic bonding diagram:
104
What does a 2D ball and stick diagram for ionic bonding show?
- 2D structure
- how many elements
- ratio of two elements
- bonds between the atoms
105
Limitations of the 2D ball and stick diagram for ionic bonding:
- doesn't show 3D structure
- doesn't show which elements they are
- doesn't show atomic structure - inc. electronic configuration
106
Example of a ball and stick for ionic bonding diagram:
107
What does the ball and stick diagram for ionic bonding show?
- 3D structure
- the elements
- ratio of elements
- number of elements
- the bonds
- charges of the ions
- relative size of the ions
108
Limitations of the ball and stick diagram for ionic bonding:
doesn't show atomic structure - inc. electronic configuration
109
Example of a close packed diagram for ionic bonding:
110
What does a close packed diagram for ionic bonding show?
- 3D structure of compound
- charges of each ion
- number of elements
- what the elements are relative size of ions in 3D
- arrangement of the ions
111
Limitations of the packed diagram for ionic bonding:
- doesn't show bonds between the atoms
- doesn't show atomic structure - inc. electronic configuration
112
Example of a dot and cross diagram for covalent bonding:
113
What does a dot and cross diagram for covalent bonding show?
- the type of element
- the number of elements
- ratio of elements
- electrons on the outer shell of each atom
- relative size of atoms (2D)
114
Limitations of dot and cross diagram for covalent bonding:
- doesn't show atomic structure - inc. electronic configuration
- doesn't show 3D structure
115
Example of ball and stick diagram for covalent bonding:
116
What does a ball and stick diagram for covalent bonding show?
- ratio of elements (each type of atom)
- the number of elements
- bonds between the atoms
- relative size of atoms 3D
117
Limitations of ball and stick diagram for covalent bonding:
- doesn't show atomic structure - inc. electronic configuration
- doesn't show type of elements
118
Example of space filling model for covalent bonding:
119
What does a space filling model for covalent bonding show?
- number of elements in compound
- relative size of atoms 3D
120
Limitations of space filling mode for covalent bonding:
- doesn't show atomic structure - inc. electronic configuration
- doesn't show bonds between atoms
121
Example of displayed formula (2D stick diagram) for covalent bonding:
122
What does a displayed formula (2D stick diagram)l for covalent bonding show?
- shows any lone pairs of electrons
- shows bonds between toms
- shows type of elements
- shows number of different elements]ratio of elements to each other
123
Limitations of displayed formula (2D stick diagram) for covalent bonding:
- doesn't show atomic structure - inc. electronic configuration
- doesn't show 3D structure
124
How do you explain why a substance is ionic?
- is made up of charged particles
- name the ions
- regular lattice structure
- metal + non-metal
