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Edexcel IGCSE Chemistry G Covalent Bonding Questions

Practise covalent bonding through definitions, dot-and-cross diagrams, molecular boiling points and giant covalent structure-property links.

Syllabus
First assessment 2019
Course
Chemistry 4CH1

Exam points

  • describe covalent bonds as attractions between shared electron pairs and two nuclei
  • draw dot-and-cross diagrams showing outer-shell shared pairs in small molecules
  • explain boiling point, hardness or conductivity from molecular, giant covalent or graphite structures

Covered syllabus points

1.44 Covalent bonds1.45 Covalent electrostatic attractions1.46 Covalent dot-and-cross diagrams1.47 Simple molecular structures1.48 Molecular mass and boiling point1.49 Giant covalent structures1.50 Diamond, graphite and fullerene1.51 Covalent conductivity

Question 1

[Maximum number: 4]

Question (a)

(a)

The atoms in methanol are held together by covalent bonds.

[ 4 ]

Question (i)

(i)

State what is meant by the term covalent bond.

[ 2 ]

Question (ii)

(ii)

Draw a dot-and-cross diagram to show the bonding in a molecule of methanol.

Show only the outer electrons of each atom.

[ 2 ]

Question 2

[Maximum number: 11]

This question is about the covalent compounds hydrogen chloride and silicon dioxide.

Question (a)

(a)

Describe the forces of attraction in a covalent bond.

[ 2 ]

Question (b)

(b)

Hydrogen chloride has the formula HCl

[ 4 ]

Question (i)

(i)

Draw a dot-and-cross diagram to show the bonding in a hydrogen chloride molecule.

Show only the outer shell electrons in each atom.

[ 2 ]

Question (ii)

(ii)

Explain why the boiling point of hydrogen chloride is low.

[ 2 ]

Question (c)

(c)

The diagram shows part of the structure of silicon dioxide.

Figure for Question (c) — Edexcel IGCSE Chemistry
[ 5 ]

Question (i)

(i)

Silicon dioxide has the same structure as diamond.

Silicon dioxide is very hard and has a very high melting point.
Explain these properties.
Refer to the structure and bonding of silicon dioxide in your answer.

[ 5 ]

Question 3

[Maximum number: 2]

A student uses this apparatus to investigate the decomposition of hydrogen peroxide solution.

Figure for Question 3 — Edexcel IGCSE Chemistry

This is the equation for the reaction.

2H2O2→2H2O+O22 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}

Complete the dot-and-cross diagram for a molecule of hydrogen peroxide.

Show outer electrons only.

Figure for Question 3 — Edexcel IGCSE Chemistry
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