Free Covalent bonding & giant structures questions for IGCSE Chemistry (0620), part of Atoms, elements & compounds. Each question has the answer and the marking points an examiner would look for.
Generate a full Covalent Bonding & Giant Structures worksheet →All Atoms, elements & compounds questionsWhich row describes silicon(IV) oxide?
| type of structure | melting point | conducts electricity when molten | |
|---|---|---|---|
| A | giant covalent | high | no |
| B | giant covalent | high | yes |
| C | giant ionic | high | yes |
| D | simple molecular | low | no |
Answer: A
Which substance has a giant covalent structure?
Answer: A
How many electrons are shared in covalent bonds in one molecule of ethene, C2H4?
Answer: D
Carbon dioxide has a double bond.
State the number of shared electrons between each oxygen atom and the carbon atom.
Compare the melting points of carbon dioxide and silicon(IV) oxide, and explain the difference.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 4 four (two pairs) B1 | 1 |
| (b) | CO₂ low; SiO₂ high; simple molecular vs giant covalent CO₂ has a low melting point, SiO₂ high B1 CO₂ is simple molecular with weak intermolecular forces B1 SiO₂ is giant covalent with many strong covalent bonds B1 | 3 |
Ammonia, NH₃, is a covalent compound.
Describe the bonding in ammonia using a dot-and-cross description.
Explain why ammonia is a gas at room temperature.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 3 shared pairs, 1 lone pair three single covalent bonds (shared pairs) between N and H B1 one non-bonding pair on N B1 | 2 |
| (b) | weak intermolecular forces simple molecules B1 weak intermolecular forces need little energy to overcome B1 | 2 |
Methane, CH₄, is a covalent compound.
Describe what is meant by a covalent bond.
Explain why methane has a low boiling point.
Explain why methane does not conduct electricity.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | shared pair of electrons a shared pair of electrons between two atoms B1 | 1 |
| (b) | weak intermolecular forces methane is a simple molecular substance B1 the intermolecular forces between molecules are weak and need little energy to overcome B1 | 2 |
| (c) | no ions or free electrons there are no ions or free electrons to carry charge B1 | 1 |
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