Structure & Bonding (Double) quiz

1. What is needed to complete this diagram to show the ionic bonding in potassium oxide, K₂O ?

1) eight electrons around the oxide (six dots and two cross) 2) A charge of +2 on the potassium and -1 on the oxide 3) A second potassium ion the same as the first

1) eight electrons around the oxide (six dots and two cross) 2) A charge of +1 on the potassium and -2 on the oxide 3) A second oxide ion the same as the first

1) eight electrons around the oxide (six dots and two cross) 2) A charge of +1 on the potassium and -2 on the oxide 3) A second potassium ion the same as the first

1) eight electrons around the potassium (any combination of dots and one crosses) 2) A charge of +2 on the oxide and -1 on the potassium 3) A second potassium ion the same as the first

Question 1 of 12

2. Why is the melting point of a smaller molecule lower than that of a larger molecule?

Larger molecules have more attractions between them. These take less energy to overcome.

Larger molecules have fewer attractions between them. These take more energy to overcome.

Larger molecules have more attractions between them. These take more energy to overcome.

Larger molecules have fewer attractions between them. These take less energy to overcome.

Question 2 of 12

3. Explain why Silica, SiO₂ is a solid with a high melting point

Silica has a giant metallic structure with weak forces of attraction between layers

Silica has a simple molecular structure with weak intermolecular forces that require little energy to overcome

Silica has a simple molecular structure with strong intermolecular forces that require a lot of energy to overcome

Silica has a giant covalent structure with many strong covalent bonds that need a lot of energy to break

Question 3 of 12

4. In the dot and cross diagram of the outer electrons showing the covalent bonding in a molecule of methane (CH₄), how many electrons should be shown in areas 1, 2, 3, and 4?

There should be two electrons in each of the areas 1, 2, 3 and 4, and an additional 6 electrons around the outside of each hydrogen atom

There should be one electron in each of the areas 1, 2, 3 and 4

There should be four electrons in each of the areas 1, 2, 3 and 4

There should be two electrons in each of the areas 1, 2, 3 and 4

Question 4 of 12

5. Explain, in terms of structure and bonding, why sodium chloride has a very high melting point

NaCl has a simple molecular structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break

NaCl has a simple molecular structure with weak intermolecular forces that require little energy to break

NaCl has a giant ionic structure with weak electrostatic forces between oppositely charged ions that require little energy to break

NaCl has a giant ionic structure with strong electrostatic forces between oppositely charged ions that require a lot of energy to break

Question 5 of 12

6. Describe the formation of a covalent bond

The electrostatic attraction between positive metal ions and a sea of delocalised electrons

The sharing of a single electron between two nuclei

The transfer of electrons from one atom to another

The sharing of a pair of electrons between two nuclei

Question 6 of 12

7. Explain why methane gas, CH₄, is a gas at room temperature

Methane has a giant covalent structure with many weak covalent bonds which require little energy to overcome

Methane has a giant covalent structure with many strong covalent bonds which require a lot of energy to overcome

Methane has a simple molecular structure with strong intermolecular forces that require a lot of energy to overcome

Methane has a simple molecular structure with weak intermolecular forces that require little energy to overcome

Question 7 of 12

8. A substance is found not to conduct electricity even when molten. What type of bonding does the substance have?

Metallic

Covalent or ionic

Covalent

Ionic

Question 8 of 12

9. Explain, in terms of its structure, why graphite can act as a lubricant.

Graphite is a smooth metal so creates a surface with little friction

Graphite has strong forces of attraction between layers. These layers can slide over each other

Graphite has a low melting point so becomes liquid when heated by friction

Graphite has weak forces of attraction between layers. These layers can slide over each other

Question 9 of 12

10. When can ionic substances conduct electricity?

In any state

Never

When molten or dissolved

Only when molten

Question 10 of 12

11. Explain the term ionic bond

An ionic bond is the strong electrostatic attraction between similarly charged ions

An ionic bond is the strong electrostatic attraction between a shared pair of electrons and two nuclei

An ionic bond is the strong magnetic attraction between oppositely charged ions

An ionic bond is the strong electrostatic attraction between oppositely charged ions

Question 11 of 12

12. Give the definition of a covalent bond

Strong electrostatic attraction between oppositely charged ions

Strong electrostatic attraction between a postive ion and a sea of delocalised positive ions

Strong electrostatic attraction between a shared pair of electrons and a nucleus

Strong electrostatic attraction between a shared pair of electrons and two nuclei

Question 12 of 12

Structure & Bonding (Double) quiz

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