IGCSE QUESTIONS SET X (Structure)
The structures of diamond and graphite are drawn below.
= carbon atom
Strong bonds
Weak bonds
Diamond graphite
(a) Name the type of strong bond shown on the diagram.
......................................................................................................................................[1]
(b) Diamond has a melting point of about 3700 C and graphite has a melting point of about
3300 C.
(i) Explain why both diamond and graphite have very high melting points.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(ii) Suggest why the melting point of graphite is lower than that of diamond.
...................................................................................................................................
...................................................................................................................................
[3]
(c) Compare the electrical conductivity of diamond and graphite.
Explain your answer.
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[2]
Total / 6
IGCSE QUESTIONS SET X (Structure)
Diamond and graphite are allotropes of carbon. They are both composed of
macromolecules.
Diamond Graphite
(a) Explain the meaning of the following terms.
(i) allotropes
...................................................................................................................................
...................................................................................................................................
(ii) macromolecule
...................................................................................................................................
...................................................................................................................................
[2]
(b) Graphite is used to make lubricants for engines.
Explain, in terms of its structure, why graphite can act as a lubricant.
..........................................................................................................................................
......................................................................................................................................[2]
(c) Give one use of diamond which depends on its hardness.
......................................................................................................................................[1]
Total / 5
IGCSE QUESTIONS SET X (Structure)
1 The structures of some substances are shown below.
Na+ I Na+ I Na+
I Na+ I Na+ I
H H H H
Na+ I
Na +
I
Na +
C H C C C H
H H I Na+ Na+
I I H
H
A B
B C
C
C C
C C C
C C C
C C C C
C C C
C C C
C C
C C C C
C C C C
C C C CC C CC
H Br C C C C
D E
(a) Answer these questions using the letters A, B, C, D or E.
(i) Which structure is methane? [1]
(ii) Which two structures are giant structures? and [1]
(iii) Which two structures are hydrocarbons? and [1]
(iv) Which structure contains ions? [1]
(v) Which two structures have very high melting points?
and [1]
Total / 5
2 Calcium and other minerals are essential for healthy teeth and bones. Tablets can be taken to
provide these minerals.
Healthy
Bones
Each tablet
contains
calcium
magnesi
um zinc
cop
per
bo
ro
n
(a) Boron is a non-metal with a macromolecular structure.
(i) What is the valency of boron?
...........................................................................
(ii) Predict two physical properties of boron.
...................................................................................................................................
...................................................................................................................................
(iii) Name another element and a compound that have macromolecular
structures. element ..
compound
(iv) Sketch the structure of one of the above macromolecular substances.
(b) Describe the reactions, if any, of zinc and copper(II) ions with an excess of aqueous sodium
hydroxide.
(i) zinc ions
addition of aqueous sodium hydroxide .....................................................................
...................................................................................................................................
excess sodium hydroxide ..........................................................................................
...................................................................................................................................
(ii) copper(II) ions
addition of aqueous sodium hydroxide .....................................................................
...................................................................................................................................
excess sodium hydroxide ..........................................................................................
...............................................................................................................................[4]
(c) Each tablet contains the same number of moles of CaCO3 and MgCO3. One tablet
reacted with excess hydrochloric acid to produce 0.24 dm3 of carbon dioxide at r.t.p.
CaCO3 + 2HCl CaCl2 + CO2 + H2O
MgCO3 + 2HCl MgCl2 + CO2 + H2O
(i) Calculate how many moles of CaCO3 there are in one tablet.
number of moles CO2 = ..............
number of moles of CaCO3 and MgCO3 = ..............
number of moles of CaCO3 = ..............
[3]
(ii) Calculate the volume of hydrochloric acid, 1.0 mol / dm3, needed to react with
one tablet.
number of moles of CaCO3 and MgCO3 in one tablet = ..............
Use your answer to (c)(i).
number of moles of HCl needed to react with one tablet = ..............
1 It was reported from America that a turbine engine, the size of a button, might replace batteries.
The engine would be built from silicon which has suitable properties for this purpose.
(a) (i) Why are batteries a convenient source of energy? [1]
[1]
(ii) The engine will run on a small pack of jet fuel. What other chemical is needed to
burn this fuel?
[1]
(b) Silicon has the same type of macromolecular structure as diamond.
(i) Explain why one atom of either element can form four covalent bonds.
[2]
(ii) Predict two physical properties of silicon.
[2]
(iii) Name a different element that has a similar structure and properties to silicon.
[1]
(c) Silicon is made by the carbon reduction of the macromolecular compound, silicon(IV)
oxide.
(i) Balance the equation for the reduction of silicon(IV) oxide.
SiO2 + C Si + CO [1]
(ii) Explain why the silicon(IV) oxide is said to be reduced.
[1]
(iii) Describe the structure of silicon(IV) oxide. You may use a diagram.
. [2]
5 (a) Copper has the structure of a typical metal. It has a lattice of positive ions and a sea
of mobile electrons. The lattice can accommodate ions of a different metal.
(
i
Give a different use of copper that depends on each of the following. )
t
he ability of the ions in the lattice to move past each other
[1]
(ii) the presence of mobile electrons
[1]
(iii) the ability to accommodate ions of a different metal in the lattice
[1]
(b) Aqueous copper(II) sulphate solution can be electrolysed using carbon electrodes. The
ions present in the solution are as follows.
Cu 2+(aq), SO42 (aq), H +(aq), OH (aq)
(i) Write an ionic equation for the reaction at the negative electrode (cathode).
[1]
(ii) A colourless gas was given off at the positive electrode (anode) and the solution
changes from blue to colourless.
Explain these observations.
[2]
(c) Aqueous copper(II) sulphate can be electrolysed using copper electrodes. The reaction at
the negative electrode is the same but the positive electrode becomes smaller and the solution
remains blue.
[1]
(i) Write a word equation for the reaction at the positive electrode.
[1]
(ii) Explain why the colour of the solution does not change.
[2]
(iii) What is the large scale use of this electrolysis?
[1]
4 The first three elements in Group IV are
carbon,
silicon,
germanium.
(a) The element germanium has a diamond-type structure. Describe the structure of
germanium. A diagram is acceptable.
[2]
(b) Unlike diamond, graphite is soft and is a good conductor of electricity.
(i) Explain why graphite has these properties.
[3]
(ii) Give a use of graphite that depends on one of these properties.
property
use [1]
(c) Carbon dioxide and silicon(IV) oxide have similar formulae but different types of
structure.
(i) Give the formulae of these oxides.
[1]
(ii) How are their structures different?
[2]
(d) All these elements form compounds with hydrogen called hydrides. The saturated
hydrides of carbon are the alkanes. Predict the formula of the hydride of germanium
which contains two germanium atoms.
[1]
[1
This question is about diamond and graphite.
Look at the diagrams. They show the structure of diamond and graphite.
(a) Diamond and graphite are forms of the same element.
Write down the name of this element.
..........................................................................................................................................[1]
(b) Diamond and graphite have several important uses.
Draw a straight line from each use to the reason why diamond or graphite is suitable for
this use.
use reason
Graphite is used in pencil because it conducts
leads electricity
Diamond is used in cutting because it sparkles and is
tools transparent
because it is has a high
Graphite is used as an
melting point and is very
electrode in electrolysis
hard
because it is slippery
Diamond is used in
jewellery
[3]
[Total: 4]
2 Diamond and graphite have different properties and different uses.
Look at the table.
It shows some information about the properties of diamond and graphite.
property diamond graphite
state at room temperature solid
.........................................
appearance at room
colourless, clear and lustrous dull black
temperature
melting point very high
.........................................
hardness very hard soft
solubility in water insoluble insoluble
electrical conductivity does not conduct good conductor
(a) Complete the table by writing in
the state of graphite at room temperature
the melting point of graphite.
[2]
(b) Diamond is used in jewellery.
This is because diamond is colourless, clear and
lustrous. Diamond is also used to make cutting tools.
Write about two properties of diamond that make it suitable for making cutting
tools. Use the table to help you.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
[Total: 4]
1 Diamond and graphite have different properties and different uses.
Look at the table.
It shows some information about the properties of diamond and graphite.
property diamond graphite
state at room temperature solid solid
appearance at room
colourless, clear and lustrous dull black
temperature
melting point very high very high
hardness very hard soft
solubility in water insoluble insoluble
electrical conductivity does not conduct good conductor
(a) Diamond is used in jewellery.
This is because diamond is colourless, clear and
lustrous. Diamond is also used to make cutting tools.
Write about two properties of diamond that make it suitable for cutting
tools. Use the table to help you.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) Look at the structures of diamond and graphite.
= carbon atom
strong bond
strong bond
weak bond
(i) Diamond and graphite both have very high melting points.
Explain why.
Use ideas about their structure.
...........................................................................................................................................
.......................................................................................................................................[1]
(ii) Graphite conducts electricity.
Explain why.
Use ideas about its structure.
...........................................................................................................................................
.......................................................................................................................................[1]
[Total: 4]
2 Diamond and graphite have different properties and different uses.
Look at the table.
It shows some information about the properties of diamond and graphite.
property diamond graphite
state at room temperature solid
.........................................
appearance at room
colourless, clear and lustrous dull black
temperature
melting point very high
.........................................
hardness very hard soft
solubility in water insoluble insoluble
electrical conductivity does not conduct good conductor
(a) Complete the table by writing in
the state of graphite at room temperature
the melting point of graphite.
[2]
(b) Diamond is used in jewellery.
This is because diamond is colourless, clear and
lustrous. Diamond is also used to make cutting tools.
Write about two properties of diamond that make it suitable for making cutting
tools. Use the table to help you.
.................................................................................................................................................
..
.................................................................................................................................................
..
.................................................................................................................................................
..
...............................................................................................................................................
[2]
[Total:
4]
1 Diamond and graphite have different properties and different uses.
Look at the table.
It shows some information about the properties of diamond and graphite.
property diamond graphite
state at room temperature solid solid
appearance at room
colourless, clear and lustrous dull black
temperature
melting point very high very high
hardness very hard soft
solubility in water insoluble insoluble
electrical conductivity does not conduct good conductor
(a) Diamond is used in jewellery.
This is because diamond is colourless, clear and
lustrous. Diamond is also used to make cutting tools.
Write about two properties of diamond that make it suitable for cutting
tools. Use the table to help you.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) Look at the structures of diamond and graphite.
= carbon atom
strong bond
strong bond
weak bond
diamond graphite
(i) Diamond and graphite both have very high melting points.
Explain why.
Use ideas about their structure.
...........................................................................................................................................
.......................................................................................................................................[1]
(ii) Graphite conducts electricity.
Explain why.
Use ideas about its structure.
...........................................................................................................................................
.......................................................................................................................................[1]
[Total: 4]
(b) Structure E is a form of carbon.
(i) What is the name of this structure?
Put a ring around the correct answer.
carbide graphite lead poly(hexene) [1]
(ii) Name another form of carbon.
[1]
(c) Write the simplest formula for substance B.
[1]
(d) Is substance D an element or a compound?
Explain your answer.
[1]
(b) Structure F is lead.
(i) What is the source of the small amount of lead present in the air?
[1]
(ii) State an adverse effect of lead on health.
[1]
(c) Structure A is sulphur. Explain why burning fossil fuels containing sulphur is harmful to
the environment.
[2]
[Total: 11]
2 Complete the following table.
electrical electrical
type of
particles present conductivity conductivity of example
structure
of solid liquid
positive and negative
ionic poor
ions
atoms of two different
macro
elements in a giant poor poor
molecular
covalent structure
metallic and good copper
[Total: 6]
(c) State the chemical name of structure B.
[1]
(d) Structure F has several uses. Which one of the following is a correct use of structure F?
Tick one box.
for cutting metals
as a lubricant
for filling balloons
as an insulator
[1]
(e) The structures A to E are compounds. What do you understand by the term compound?
[1]
(f) State the type of bonding in structure A.
[1]
[Total: 10]
