IGCSEChemistry: Double ScienceEdexcelTopic Questions1. Principles of Chemistry1.7 Covalent Bonding

Covalent Bonding (Edexcel IGCSE Chemistry: Double Science)

Topic Questions

DownloadView
Medium
Hard
Medium
Hard
1a
Sme Calculator2 marks

Halon 1301 is a compound used in some fire extinguishers.

Halon 1301 has the percentage composition by mass of

C 8.05%   Br 53.69%   F 38.26%

a)
Show, by calculation, that the empirical formula of this compound is CBrF3 
 
(2)

How did you do?

1b2 marks
b)
The diagram shows the displayed formula of a molecule of Halon 1301.
 
cbrf3-halon-1301
 
Draw a dot-and-cross diagram to show all the outer electrons in this molecule.
 
(2)

How did you do?

1c2 marks
c)
The boiling point of Halon 1301 is —58°C.
 
Explain why Halon 1301 has a low boiling point.
 
(2)

How did you do?

Did this page help you?

1a2 marks

Diamond, graphite and silicon dioxide all have giant covalent structures.

The diagram shows the structures of these three substances.

covalent-structures-edexcel-2019ju1c

a)
Explain why silicon dioxide has a high melting point.
 
(2)

How did you do?

1b2 marks
b)
Explain why graphite conducts electricity. 
 
 (2)

How did you do?

1c2 marks
c)
State why diamond is hard but graphite is soft.
 
(2)

How did you do?

Did this page help you?

2a3 marks
a)
Carbon dioxide changes directly from a solid to a gas without becoming a liquid.

i)
Give the name of the change of state from solid to gas.

[1]

ii)
Describe the test for carbon dioxide gas.

[2]

How did you do?

2b2 marks
b)

Carbon dioxide is a simple molecular covalent substance.

Explain why carbon dioxide turns from a solid to a gas at a very low temperature.

[2]

How did you do?

2c6 marks
c)
Diamond and graphite are both giant covalent substances made up of carbon atoms.

  • diamonds are used in cutting tools
  • graphite is used in pencils to make marks on paper
Explain, with reference to structure and bonding, why each substance is suitable for its particular use.

[6]

How did you do?

Did this page help you?

3a2 marks
a)
Chlorine, bromine and iodine are elements in the Periodic Table.
 
Explain how the position of these elements in the Periodic Table depends on their electronic configurations.
 
(2)

How did you do?

3b8 marks
b)
Chlorine reacts with methane to form CH3Cl and HCl
 
i)
State the condition necessary for this reaction.
 
(1)
 
ii)
Give the equation for this reaction.
 
(1)
 
iii)
The bonds in a molecule of CH3Cl are covalent.
 
Explain, in terms of electrostatic attractions, what is meant by a covalent bond.
 
(2)
 
iv)
Draw a dot‐and‐cross diagram for a molecule of CH3Cl
 
Show only the outer electrons of the atoms.
 
(2)
 
chloromethane-dot-and-cross-blank
 
v)
CH3Cl has a simple molecular structure.
 
Explain why CH3Cl has a low boiling point.
 
(2)

How did you do?

3c2 marks
c)
Graphite is another substance that contains covalent bonds.
 
The diagram shows the structure of graphite.
 
graphite-edxcel-2020nov1c
 
Most covalent substances do not conduct electricity.
 
Explain why graphite is able to conduct electricity.
 
(2)

How did you do?

Did this page help you?

4a4 marks

This question is about substances with covalent bonds.

a) i)
Draw a dot and cross diagram to show the outer shell electrons in a molecule of nitrogen, N2
 
(2)
 
blank-diatomic-dot-and-cross
 
ii)
Describe the forces of attraction in a covalent bond.
 
(2)

How did you do?

4b5 marks
b)
The diagram shows three different structures of carbon.
 
diamond graphite fullerene
Structure A Graphite C60 Fullerene
 
i)
Name structure A.
 
(1)
 
ii)
Graphite and C60 fullerene contain covalent bonds, but have different structures.
 
Explain why C60 fullerene has a much lower melting point than graphite.
 
Refer to structure and bonding in your answer.
 
(4)

How did you do?

Did this page help you?

51 mark

Carbon dioxide contains covalent bonds.

The covalent bonds in a molecule of carbon dioxide can be represented by a dot-and-cross diagram.

Which is the correct dot-and-cross diagram for carbon dioxide?

(1)

  ☐ A co2-bonding-option-a
  ☐ B co2-bonding-option-b
  ☐ C co2-bonding-option-c
  ☐ D co2-bonding-option-d

How did you do?

Did this page help you?

6a3 marks
a)
Diamond is a naturally‐occurring form of carbon.

It has a giant molecular structure.

Explain, with reference to its structure and bonding, why diamond has a high melting point.

(3)

How did you do?

6b3 marks
b)
C60 fullerene is another form of carbon.

The diagram shows a molecule of C60 fullerene.

2019-ju1cr-q9b

i)
Explain why C60 fullerene has a much lower melting point than diamond.

(2)

ii)
C60 fullerene is used by doctors when injecting medicines into their patients.

C60 fullerene allows medicines, which might damage some parts of the body, to reach the part of the body where they are needed.

Suggest why C60 fullerene is suitable for this purpose.

(1)

How did you do?

6c5 marks
c)
Graphite is another naturally‐occurring form of carbon.
Graphite can be used in pencils because it is soft and can leave marks on paper.
Graphite can also be used as a conductor of electricity.

Explain why graphite is soft and conducts electricity.
Refer to structure and bonding in your answer.
(5)

How did you do?

Did this page help you?

7a4 marks

This question is about carbon and its compounds.

a) i)
Draw a dot-and-cross diagram to show the outer shell electrons in a molecule of carbon dioxide, CO2.
 

(2)

ii)
The atoms in carbon dioxide are held together by covalent bonds.
Describe the forces of attraction in a covalent bond.

(2)

How did you do?

7b7 marks
b)
The diagram shows three different structures of carbon.
 
allotropes-of-carbon
i)
Explain why graphite conducts electricity.

(2)

ii)
Explain why diamond has a much higher melting point than C60 fullerene.
Refer to structure and bonding in your answer.

(5)

How did you do?

Did this page help you?

81 mark

Silicon dioxide, SiO2, and silicon(IV) chloride, SiCl4, are both covalently bonded compounds.

The table below shows the melting point and boiling point of these compounds.

Compound Melting point / o C Boiling point / o C
Silicon dioxide 1710 2230
Silicon(IV) chloride -69 58

Which statement is not correct about the two compounds?

(1)

  ☐ A at room temperature silicon dioxide is a solid and silicon(IV) chloride is a liquid
  ☐ B silicon dioxide has a giant covalent structure
  ☐ C silicon(IV) chloride has a lower melting point as it has fewer covalent bonds to overcome
  ☐ D silicon(IV) chloride has a simple molecular structure

How did you do?

Did this page help you?

9a2 marks

This question is about some compounds of the elements in Group 4 of the Periodic Table.

a)
When carbon dioxide dissolves in water, a weak acid forms.

i)
Which of these could be the pH of this weak acid?

(1)

  ☐ A 1
  ☐ B 5
  ☐ C 7
  ☐ D 9

ii)
Which of these is a correct statement about acids?
(1)
  ☐ A acids contain OH− ions
  ☐ B acids are electron donors
  ☐ C acids are proton acceptors
  ☐ D acids are proton donors

How did you do?

9b2 marks
b)
When lead(II) carbonate is heated, lead(II) oxide and carbon dioxide form.

i)
Give the name of this type of reaction.
(1)
ii)
Complete the equation for this reaction.
(1)

PbCO3 → .............................................. + ..............................................

How did you do?

9c7 marks
c)
Silicon dioxide, SiO2, and silicon(IV) chloride, SiCl4, are both covalently bonded compounds. The table shows the melting and  boiling points of these two compounds, and the physical state of silicon dioxide at room temperature.

Compound Melting point in °C Boiling point in °C Physical state at
room temperature
SiO2 1710 2230 solid
SiCl4 −69 58  

i)
Complete the table by giving the physical state of silicon(IV) chloride at room temperature.

(1)

ii)
Explain, in terms of structure and bonding, why silicon dioxide has a much higher melting point than silicon(IV) chloride.

(6)

How did you do?

Did this page help you?

101 mark

#The diagram shows the structures of three substances that have giant covalent structures.

1-7-q4-edexcel-igcse-chemistry 

Which does not provide the correct explanation of the property of a substance?

  Substance Property Explanation
A graphite conducts electricity its ions are free to move through the layers
B diamond hard each carbon atom is covalently bonded to four other carbon atoms
C silicon dioxide high melting point it has many strong covalent bonds which require a large amount of energy to break
D graphite soft its layers can slide over each other

(1)

  ☐ A  
  ☐ B  
  ☐ C  
  ☐ D  

How did you do?

Did this page help you?

111 mark

Ammonia, NH3, is a small covalent molecule.

How many non-bonding, outer-shell electrons are present in one molecule of ammonia?

(1)

  ☐ A 0
  ☐ B 2
  ☐ C 5
  ☐ D 6

How did you do?

Did this page help you?