Metallic Bonding

5 marks · Hard

Zinc is used to galvanise iron to prevent rusting because it is strong and resistant. Answer the following about the properties of zinc metal and its bonding.

(a)

State and explain, in terms of metallic bonding, why zinc conducts electricity.

[2 marks]

(b)

Zinc can be hammered into thin sheets. Explain why this is possible, referring to its structure and bonding.

[2 marks]

(c)

Zinc has a high melting point. Explain this property in terms of attraction between its particles.

[1 mark]

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(a) —

(b) —

Common mistakes: Not mentioning delocalised electrons; Referring to layers for properties like conductivity

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Mentions delocalised electrons moving through the structure.

A1 (a) · 1 mark · Links movement of electrons to electrical conductivity.

M2 (b) · 1 mark · Mentions layers of positive ions (or particles) can slide over each other.

A2 (b) · 1 mark · Explains metallic bonding is unchanged as ions remain attracted to delocalised electrons.

A3 (c) · 1 mark · States there are strong electrostatic attractions between ions and delocalised electrons (requiring much energy to break).

Worked solution

a) In zinc metal, delocalised electrons are free to move throughout the structure. This movement of electrons allows zinc to conduct electricity.

b) Zinc can be hammered into thin sheets because the layers of positive ions in its lattice can slide over each other when a force is applied. The metallic bonding does not break, because the positive ions remain surrounded by the delocalised electrons.

c) Zinc has a high melting point because strong electrostatic attractions between positive ions and delocalised electrons require a lot of energy to overcome.