Core questions – Chemistry unit 2 – Bonding and Structure
No. Question Answer
1 Where does ionic bonding occur? In compounds formed from metals combined with non-metals
2 Where does covalent bonding occur? Non-metallic elements and in compounds of non-metals
3 Where does metallic bonding occur? In metallic elements and alloys
4 What charge does an ion have when an atom has lost electrons? Positive
5 What charge does an ion have when an atom has gained
electrons?
Negative
6 Describe ionic bonding The attraction between oppositely charged ions
7 How are ionic compounds held together? With strong electrostatic forces of attraction between the oppositely charged ions
8 What does a dot cross diagram look like for sodium and chlorine
reacting to form sodium chloride (only including the outer shell)?
9 What does a ball and stick model of sodium chloride look like?
10 What are the disadvantages of using a ball and stick model to
represent ionic compounds?
The model doesn’t show the relative sizes of of the ions and it shows gaps between the
ions, whereas in reality, there are no gaps between the ions
11 How can you calculate the empirical formula from a 3D diagram of
an ionic lattice?
STEP 1: Look at the diagram to work
out what ions are in the compound
(e.g potassium ions and oxide ions)
STEP 2: Work out what charges the
ions will form
STEP 3: Balance the charges so the
charge of the empirical formula is zero
Potassium is in group 1 so forms 1+ ions
Oxygen is in group 6 so forms 2- ions
A potassium ion only has a 1+ charge, so you’ll
need two of them to balance out the 2- charge
of an oxide ion.
The empirical formula is K2O
12 What charge do ions formed from group 1 elements have? 1+
13 What charge do ions formed from group 2 elements have? 2+
14 What charge do ions formed from group 6 elements have? 2-
15 What charge do ions formed from group 7 elements have? 1-
16 What is a covalent bond? A shared pair of electrons
17 Name 8 simple covalent molecules? Hydrogen; chlorine; oxygen; nitrogen; hydrogen chloride; water; ammonia; methane
18 What does a dot cross diagram for hydrogen look like?
19 What does a dot cross diagram for chlorine look like?
20 What does a dot cross diagram for oxygen look like?
21 What does a dot cross diagram for nitrogen look like?
22 What does a dot cross diagram for hydrogen chloride look like?
23 What does a dot cross diagram for water look like?
24 What does a dot cross diagram for ammonia look like?
25 What does a dot cross diagram for methane look like?
26 How else can simple covalent structures be represented other
than dot and cross diagrams? Displayed formula (e.g. )
3D structure (e.g )
27 What is a polymer? Long chains of repeating units (monomers)
28 How are the atoms in a polymer held together? With covalent bonds
29 How can polymers be represented?
30 What is metallic bonding? A lattice of positively charged metal ions surrounded by delocalised electrons
31 How are atoms held together in metallic bonding? Electrostatic attraction between the delocalised electrons and the positive metal ions
32 Name the process of a solid turning into a liquid Melting
33 Name the process of a liquid turning into a solid Freezing
34 Name the process of a liquid turning into a gas Boiling
35 Name the process of a gas turning into a liquid Condensing
36 Name the process of a solid turning into a gas Subliming
37 How is the strength of the forces between particles and the
melting and boiling point of a substance related?
The stronger the forces the higher the melting/boiling point
38 What are the limitations of the particle model? In the model there are no forces, particles are represented as spheres, the spheres are
solid
39 What does the state symbol (s) represent? Solid
40 What does the state symbol (l) represent? Liquid
41 What does the state symbol (g) represent? Gas
42 What does the state symbol (aq) represent? Aqueous
43 What does aqueous mean? Dissolved in water
44 What are the properties of ionic compounds? High melting and boiling points; can conduct electricity when molten (or dissolved), but
not as a solid
45 Why do ionic compounds have high melting/boiling points? Large amount of energy is needed to break the strong attractions between oppositely
charged ions
46 Why don’t solid ionic compounds conduct electricity? The ions are not free to move
47 Why do aqueous and liquid ionic compounds conduct electricity? The ions are free to move
48 What are the properties of simple molecules? Low melting and boiling points; do not conduct electricity
49 Why are simple molecules usually gases or liquids at room
temperature?
They have low melting and boiling points
50 Why do simple molecules have low melting /boiling points? The forces between the molecules are weak (intermolecular forces) and so require
little energy to break
51 What is broken when simple molecules are melted/boiled? The forces between the molecules (the intermolecular forces)
52 Why do larger molecules have higher melting points? Larger molecules have stronger intermolecular forces
53 Why don’t simple molecules conduct electricity? The molecules do not have an overall electric charge AND do not have free flowing
electrons
54 Why are polymers solid at room temperature? Polymers are very large molecules and so have strong intermolecular forces
55 What is a giant covalent structure? One where all the atoms in the structure are covalently bonded to other atoms
56 Name three giant covalent structures. Diamond, graphite, silicon dioxide
57 Why do giant covalent structures have high melting points? Lots of energy is needed to break the covalent bonds between the atoms
58 What are the properties of pure metals? High melting and boiling points; easily bent and shaped
59 Why do metals have high melting/boiling points? The strong electrostatic attraction between the positive metal ions and the delocalised
electrons needs lots of energy to be broken
60 Why can pure metals be easily bent and shaped? The atoms are arranged in layers, which allows the atoms to slide over each other
easily
61 What is an alloy? A substance made of two or more elements, at least one of which is a metal
62 Why are alloys harder than pure metals? The layers of metal ions are distorted by the differing size of the other atoms, which
prevents the layers from sliding over each other as easily
63 Why are metals good conductors of electricity? Because the delocalised electrons can carry electrical charge throughout the structure
64 Why are metals good conductors of heat? Because thermal energy can be transferred by the delocalised electrons
65 Describe the structure of diamond. Each carbon atom is covalently bonded to four others
66 What are the properties of diamond? High melting point, hard, doesn’t conduct electricity
67 Why does diamond have a high melting point? The strong covalent bonds between each atom takes a lot of energy to break
68 Why is diamond hard? Because each carbon atom forms four covalent bonds with other carbon atoms
69 Why doesn’t diamond conduct electricity? Because it does not have free electrons that are able to move
70 Describe the structure of graphite. Each carbon atom is covalently bonded to three others to form layers of hexagonal
rings
71 How are the layers in graphite held together? Intermolecular forces
72 What are the properties of graphite? High melting point; soft; can conduct thermal and electrical energy
73 Why does graphite have a high melting point? The strong covalent bonds between each atom takes a lot of energy to break
74 Why can graphite conduct electricity? One electron from each carbon atom is delocalised and can carry charge through the
structure
75 Why is graphite soft and slippery? Because the layers are held by weak intermolecular forces, so are able to slide over
each other easily
76 What is graphene? A single layer of graphite
77 What are the properties of graphene? Very light; very strong; can conduct electricity
78 What real life applications can graphene be used for? Composite materials and in electronic equipment
79 Why can graphene be used in composite materials? It makes materials very strong without adding too much weight
80 Why can graphene be used in electronics? It has delocalised electrons meaning it can conduct electricity
81 What is a fullerene? A molecule of carbon atoms with a hollow shape
82 Describe the structure of a fullerene? Mainly made of carbon atoms arranged in hexagons. They can also contain pentagon
(5) or heptagon (7) rings
83 What was the first fullerene to be discovered? Buckminsterfullerene (C60) and forms a hollow sphere
84 Give two uses of fullerenes? They can be used to ‘cage’ other molecules, meaning they could be used to deliver
drugs to inside the body
They have can be used as catalysts because they have huge surface areas
85 What is a carbon nanotube? Cylindrical fullerenes with very high length to diameter ratios
86 What do the properties of carbon nanotubes makes them useful
for?
Nanotechnology, electronics, materials
87T What type of structures does Nano science refer to? (Triple only) Structures that are 1-100 nm in size, of the order of a few hundred atoms
88T What is the diameter of a fine particle (PM2.5)? (Triple only) Between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m)
89T What is the diameter of a coarse particle (PM10)? (Triple only) Between 2500 and 10 000 nm (1 x 10-5 m and 2.5 x 10-6 m)
90T What are coarse particles more commonly referred to as? (Triple
only)
Dust
91T If the side of a cube decreases by a factor of 10, what does the
surface area to volume ratio increase by? (Triple only)