Covalent Bonding (Edexcel GCSE Chemistry)

Exam Questions

3 hours32 questions
1a1 mark

Figure 1 shows the bonding in ammonia. 

1-4-covalent-bonding-1a

Figure 1

What is the formula of ammonia? Draw a ring around the correct answer. 

NH NH2 NH3 N3H

1b1 mark

Use the correct answer from the box to complete the sentence.

delocalised                shared                 transferred

When a nitrogen atom and a hydrogen atom bond to produce ammonia, electrons are ...............................

1c1 mark

What is the type of bonding in ammonia?

1d1 mark

Ammonia only contains single bonds. Double bonds can also form between atoms in other molecules. 

Which of the following statements is correct?

Tick (one box. 

A double bond contains two electrons  
A double bond contains two pairs of electrons   

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2a2 marks

Hydrogen and carbon atoms form the hydrocarbon molecule methane. 

The diagram in Figure 1 shows how the outer electrons are arranged in an atom of hydrogen and carbon.  

1-4-covalent-bonding-2a-a

Figure 1

Complete Figure 2 to show how the outer electrons are arranged in a molecule of methane (CH4). 

1-4-covalent-bonding-2a-b

Figure 2

2b1 mark

What is the type of bond in a molecule in methane? 

Tick (one box. 

Metallic  
Ionic   
Covalent   
2c3 marks

Methane has a boiling point of -162 °C. At room temperature it is a gas.

Explain why methane is a gas at room temperature.

2d1 mark

Methane is a simple molecule and it does not conduct electricity. 

Which statement is the correct reason for this? 

Tick (one box. 

Electrons are fixed in position  
The ions are free to move and carry a charge   
There are no free electrons to carry the charge   
The bonds contain no electrons   

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3a1 mark

Figure 1 shows the dot and cross diagram for an oxygen molecule.

edx-1-4e-paper-2-q3a-oxygen-molecule-diagram

Figure 1

Complete the sentence:

The dots and crosses in Figure 1 represent …………..

3b1 mark

State the formula for an oxygen molecule.

3c2 marks

Figure 2 shows the electron shell of a hydrogen atom.

edx-1-4e-paper-1-q4a-hydrogen-atom-diagram

Figure 2

Two hydrogen atoms join to form a molecule.

Draw a dot and cross diagram for a hydrogen molecule.

3d1 mark

When hydrogen burns in oxygen water is formed.

The formula for a water molecule is H2O.

State how many hydrogen and oxygen atoms are in a molecule of water

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4a1 mark

Nanometres (nm) are a unit of length.

1 nm =  0.000000001 m

Scientists use nanometres and not metres to measure the size of atoms and molecules.

Give a reason why.

4b3 marks

Draw one straight line from each object to its correct size.

edx-1-4e-paper-2-q4b-table

4c1 mark

Carbon atoms have four electrons on their outer shell.

Oxygen atoms have six electrons on their outer shell.

Figure 1 shows a partially completed dot and cross diagram for a carbon dioxide molecule.

edx-1-4e-paper-2-q4d-carbon-dioxide-diagram

Figure 1

Complete Figure 1 to show all the electrons.

4d1 mark

How many non-bonding electrons does each oxygen atom have?

A

2

B

4

C

5

D

6 

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5a2 marks

Molecules contain covalent bonds.

Describe what a covalent bond is.

5b1 mark

Figure 1 shows a molecule made up of sulfur and hydrogen.

edx-1-4e-paper-2-q5b-molecule-diagram

Figure 1

Give the formula of the molecule.

5c1 mark

What is the molecule called?

A

Hydrogen sulfide

B

Hydrogen sulfur

C

Sulfur hydride

D

Sulfur hydrogen

5d2 marks

Which statements are true about the molecule in Figure 1?

Tick (✓) two boxes.

All atoms in the molecule are non-metals

 

The molecule contains double covalent bonds

 

All the electrons in the atoms are shown

 

There are 4 non-bonding electrons

 

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11 mark

An oxygen molecule, O2, is formed when two oxygen atoms covalently bond together.

How many electrons need to be shared between these two oxygen atoms?

q4-1-4-oxygen-molecule-figure

 
  A 2
  B 3
  C 4
  D 6

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21 mark

Hydrogen, carbon, oxygen and chlorine can all form covalent bonds by sharing electrons.

How many electrons does each element need to share in order to complete its outer shell?

 
      hydrogen carbon oxygen chlorine
  A 1 4 6 7
  B 1 4 2 1
  C 1 4 4 2
  D 1 2 6 2

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3a3 marks

Figure 1 shows the displayed structure of ethanol 

1-4-3a-m-ethanol-dot-cross-diagram-a

Complete the dot and cross diagram in Figure 2 to show the bonding in ethanol. Show the outer shell electrons only.

1-4-3a-m-ethanol-dot-cross-diagram-b

3b3 marks

Ethanol has a boiling point of 79 °C. Explain why ethanol has a low boiling point.

3c2 marks

Explain, in terms of particles, why ethanol does not conduct electricity.

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41 mark

Methane and water are both simple molecules containing covalent bonds.

Which statement is not correct?

  A weak intermolecular forces of attraction exist between molecules
  B a covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the atoms involved
  C methane and water do not conduct electricity as they have no free electrons
  D there is a strong electrostatic attraction within the molecule between oppositely charged ions

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5a4 marks

This question is about substances with covalent bonds.

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)
5b5 marks

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)

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61 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?

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

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7a2 marks

Sulfur can form covalent bonds.

Complete the dot and cross diagram in Figure 1 to show the covalent bonding in a molecule of hydrogen sulfide.

1-4-7a-m-blank-so2-dot-cross-diagram


Show the outer shell electrons only.

7b1 mark

Which of the following set of properties is most likely to be hydrogen sulfide?

    Boiling point in °C Does it conduct electricity in the liquid state?
A 2230 No
B 100 No
C -60 No
D 2750 Yes

7c2 marks

The atoms in carbon dioxide are held together by covalent bonds.

Describe the forces of attraction in a covalent bond.

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1a1 mark

Diamond is made up of carbon atoms.

Figure 1 shows the structure of diamond.

The black dots represent the carbon atoms.

The lines represent bonds.

edx-1-4h-paper-2-q1a-diamond-diagram

Figure 1

Name the type of bonding in diamond.

1b3 marks

Explain why each carbon atom forms four bonds.

1c2 marks

Carbon can also form compounds like methane (CH4).

Draw a dot and cross diagram to show the bonding in methane.

Show the outer electrons only.

1d4 marks

The melting point of diamond is around 4500°C.

The melting point of methane is -182°C.

Explain this difference using your knowledge of bonding.

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2a1 mark

Ethanoic acid is the acid found in vinegar.

Figure 1 shows the dot and cross structure of ethanoic acid.

edx-1-4h-paper-2-q2a-ehtanoic-acid-dot-and-crossFigure 1

State what each dot and cross represents.

2b2 marks

Complete Figure 2 to show the structure of an ethanoic acid molecule.

Use a single line to show each bond.

edx-1-4h-paper-2-q2b-ethanoic-acid-structure

Figure 2

2c1 mark

Determine the empirical formula of ethanoic acid.

2d2 marks

The boiling point of ethanoic acid is 118°C.

The boiling point of water is 100°C.

Use your knowledge of bonding to suggest a reason for the difference.

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3a1 mark

An atom has a length of 0.1 nm.
A grain of sand has a length of 1 mm.
1 mm = 1 million nm

Calculate how many atoms could line up next to each other on a grain of sand.

3b1 mark

Calculate the order of magnitude between the length of an atom and a grain of sand.

3c2 marks

Atoms bond together to form molecules.

Show the bonding in a chlorine molecule.
Only include the electrons in the outer shell.

3d3 marks

Chlorine is found in Group 7 of the Periodic Table.
All elements in Group 7 form molecules with two atoms.

Explain how the size of the molecule changes as you go down Group 7.

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4a1 mark

Figure 1 shows the structure of hydrogen peroxide.

edx-1-4h-paper-2-q4a-hydrogen-peroxide-structureFigure 1

The lines represent covalent bonds.

Explain why hydrogen peroxide contains covalent, not ionic bonds.

4b1 mark

Calculate the relative formula mass of hydrogen peroxide.

(Mr H = 1, Mr O = 16)

4c2 marks

Complete Figure 2 to show the dot and cross diagram for hydrogen peroxide.

edx-1-4h-paper-2-q4c-hydrogen-peroxide-dot-and-cross

Figure 2

4d1 mark

A student said ‘Covalent bonds only exist between atoms of different elements’.

Use an example to show that this statement is incorrect.

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5a2 marks

This question is about trends in the sizes of atoms.

Group 0 of the Periodic table contains the noble gases.

i)
Predict how the size of the atoms changes as you go down Group 0.

 [1]

ii)
Explain your answer to part i)
[1]
5b4 marks

Figure 1 is a graph that shows how the length of atoms changes as you go across Period 3 of the Periodic Table.

edx-1-4h-paper-2-q5b-atom-length-graph

Figure 1

i)
Describe what the graph shows.

[1]

ii)
Suggest a reason for this trend.
[3]
5c2 marks

Group 7 contains the halogens.

Hydrogen reacts with halogens to form simple covalent molecules called hydrogen halides.

Draw a dot cross diagram to show the bonding in the molecule formed when hydrogen reacts with chlorine

5d3 marks

Higher Tier Only

Figure 2 shows the bond energies in hydrogen halides.

Bond

Bond energy in kJ/mol

H-F

568

H-Cl

432

H-Br

366

H-I

298

 

Figure 2

Suggest an explanation for the trend shown in Figure 2.

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