A Level Chap 5 EOC
A Level Chap 5 EOC
A Level Chap 5 EOC
Summary
■ The kinetic theory of gases states that gas particles ■ Simple molecular solids with low melting points such
are always in constant random motion at a variety as iodine have a regular arrangement of molecules;
of speeds. they are crystalline. There are weak intermolecular
forces between the molecules.
■ The volume of a gas increases when the
temperature increases and decreases when the ■ Giant covalent (giant molecular) structures such as
pressure increases. diamond have a large number of covalent bonds
arranged in a regularly repeating pattern.
■ The volume of a gas under different conditions of
■ Fullerenes are allotropes of carbon in the shape
temperature and pressure can be calculated using
of hollow spheres (buckminsterfullerene) or
the ideal gas equation pV = nRT.
tubes (nanotubes).
■ The ideal gas equation can be used to determine the
■ Graphene is composed of a single flat sheet of
relative molecular mass of simple molecules.
hexagonally-arranged carbon atoms.
■ Gases do not obey the ideal gas equation at low ■ The strong covalent bonds between the atoms in
temperatures and high pressures. giant molecular structures cause these substances to
■ The kinetic-molecular model can be used to describe have high melting and boiling points.
the states of matter in terms of proximity and motion ■ In metals, the atoms are closely packed in a giant
of the particles, and to describe changes of state and lattice in which the outer electrons are free to move.
vapour pressure. ■ Metals such as aluminium and copper and their
■ Ionic compounds such as sodium chloride and alloys have a variety of uses, which can be related to
magnesium oxide form a giant three-dimensional their physical properties, e.g. density, malleability,
conductivity, hardness. 85
lattice structure containing ions in a regularly
repeating pattern. ■ Physical data can be used to suggest the type of
■ The strong ionic forces acting in all directions structure and bonding present in a substance.
between the ions in the lattice cause ionic ■ Recycling plays an important part in conserving finite
substances to have high melting and boiling points. resources such as metals.
End-of-chapter questions
1 Four types of structure are:
giant molecular
giant ionic
giant metallic
simple molecular
a Give two examples of a giant ionic structure and two examples of a simple molecular structure. [4]
b Explain why substances with giant ionic structures are often brittle but metallic structures are malleable. [6]
c Explain why giant molecular structures have higher melting points than simple molecular structures. [6]
d Diamond and graphite are two forms of carbon with giant molecular structures. Explain why graphite
conducts electricity but diamond does not. [5]
Total = 21
Cambridge International AS Level Chemistry
2 The structures of carbon dioxide and silicon dioxide are shown in the diagram below.
O C O
B low ii iii iv
i Why is aluminium more suitable than steel for building aeroplane bodies? [1]
ii Explain why overhead electricity cables are made from aluminium with a steel core rather than
just from copper. [5]
d The effect of alloying copper with zinc on the strength of the alloy is shown in the table below.
iDescribe and explain the change in tensile strength as the percentage of zinc increases from
0% to 40%. [5]
ii State the name of the alloy of copper with zinc. [1]
e Many metals, such aluminium, can be recycled. Give three reasons why about 90% of aluminium is
made by recycling rather than extracting it from its ore. [3]
Total = 21
Cambridge International AS Level Chemistry
Use the diagrams and your knowledge of structure and bonding to answer the following questions.
a Explain why both diamond and graphite have high melting points. [2]
b i Why is graphite used in making handles for tennis racquets? [3]
ii Explain why graphite is used in pencil ‘leads’ for writing. [4]
c Explain why diamond is used on the tips of high-speed drills. [5]
Total = 14
A B C
a Give the name of allotrope A, which has the formula C60. [1]
b Explain in terms of structure and bonding why structure A is gaseous at 800 °C but diamond is not. [6]
c Structure B shows an allotrope of carbon in the form of tubes.
i Give the name of this allotrope of carbon. [1]
ii Describe the similarities and differences between structure B and graphite. [4]
d Structure C is stronger than structure B when a force is applied in the same direction as the long axis of the tube.
Explain why structure C is stronger. [5]
Total = 17