Metallic Bonding (Cambridge (CIE) O Level Chemistry): Theory Questions

For each of the following unfamiliar elements predict one physical and one chemical property.

Caesium (Cs)

Physical property .............................................................................................................. Chemical property .............................................................................................................

Vanadium (V)

Physical property ..........................................................................................................

Chemical property ..........................................................................................................

Fluorine (F)

Physical property ..........................................................................................................

Chemical property ..........................................................................................................

Sodium, magnesium and aluminium are all metals.

Describe the structure of a typical metal.

Explain why sodium, magnesium and aluminium are good conductors of electricity.

Blocks of magnesium are attached to steel pipes to stop the pipes from rusting.

Explain how the magnesium stops the steel from rusting.

The table shows the melting points, boiling points and electrical properties of five substances, A to E.

Choose a substance from the table above to match each of the following descriptions. A substance may be used once,  more than once or not at all. Justify each choice with evidence from the table.

One has been completed as an example.

This substance is covalent and is a solid at room temperature (25 °C): D Evidence: Its melting point is above room temperature. It has a low melting point and it does not conduct as a liquid, so it is covalent.

This substance has a giant covalent structure:

Evidence:

This substance is a metal:

Evidence:

This substance is a liquid at room temperature.

Evidence:

This substance is an ionic solid. 

Evidence:

Chromium is a metal. Sodium chloride is an ionic compound.

Chromium conducts electricity when it is solid.

Explain why, in terms of the structure and bonding in chromium.

Sodium chloride does not conduct electricity when it is solid, but it does conduct electricity when it is molten.

Explain why.

Both chromium and sodium chloride form giant lattices.

State one similarity between a giant metallic lattice and a giant ionic lattice.

Aluminium is used to make overhead power cables.

Aluminium can be drawn out into long cables without breaking.

Explain, in terms of its structure and bonding, why aluminium is ductile.

Copper is a better conductor of electricity than aluminium.

Suggest why aluminium is used for overhead power cables instead of copper.

Aluminium is extracted from its ore by electrolysis rather than by heating the ore with carbon.

Explain why.

Lead is an excellent roofing material. It is malleable and resistant to corrosion. Lead rapidly becomes coated with basic lead carbonate which protects it from further corrosion.

Lead has a typical metallic structure which is a lattice of lead ions surrounded by a ‘sea’ of mobile electrons. This structure is held together by attractive forces called a metallic bond.

i) Explain why there are attractive forces in a metallic structure.

[2]

ii) Explain why a metal, such as lead, is malleable.

[2]

Basic lead(II) carbonate is heated in the apparatus shown below. Water and carbon dioxide are produced.

Silica gel absorbs water. Silica gel often contains anhydrous cobalt(II) chloride. When this absorbs water it changes from blue to pink. Suggest a reason.

Basic lead(II) carbonate has a formula of the type xPbCO₃.yPb(OH)₂ where x and y are whole numbers. Determine x and y from the following information.

PbCO₃  → PbO + CO₂
Pb(OH)₂ → PbO + H₂O

When heated, the basic lead(II) carbonate gave 2.112 g of carbon dioxide and 0.432 g of water.

Mass of one mole of CO₂ = 44 g
Mass of one mole of H₂O = 18 g

Number of moles of CO₂ formed = .....................

[1]

Number of moles of H₂O formed = .....................

[1]

x = ..................... and y = .....................

Formula of basic lead(II) carbonate is ........................................................................

[1]

An ore of the important metal zinc is zinc blende, ZnS. This is changed into zinc oxide which is reduced to the impure metal by carbon reduction.

i) How is zinc oxide obtained from zinc sulfide?

[2]

ii) Write a balanced equation for the reduction of zinc oxide by carbon.

[1]

iii) The major impurity in the zinc is cadmium. The boiling point of zinc is 907°C and that of cadmium is 767 °C.

Name a technique which could be used to separate these two metals.

[2]

In common with most metals, zinc is a good conductor of electricity. It is used as an electrode in cells.

i) Give two other uses of zinc.

[2]

ii) Describe the metallic bonding in zinc and then explain why it is a good conductor of electricity.

[4]

Table 1.1 shows the melting point and the electrical conductivity of three substances.

Table 1.1

Identify which substance is a metal.

Explain how the data in Table 1.1 supports your answer.

Explain, in terms of structure and bonding, how the bonding in tin differs from the bonding in diamond.

Tin and diamond both have giant structures, but only tin conducts electricity.

Explain why.

Silver is a metal.

Describe the bonding in silver.

Use your answer to (a) to explain why silver is a good conductor of electricity.

Silver can be hammered into thin sheets without breaking.

Use your answer to (a) to explain why silver is malleable.

Silver is used to make jewellery.

Suggest one property of silver, other than being malleable, that makes it suitable for this use.

Francium is a metal in Group I of the Periodic Table. It is so rare that its electrical properties have never been measured.

Predict whether francium conducts electricity.

Explain your prediction in terms of the structure and bonding in francium.

A student says that francium must conduct electricity better than aluminium, because francium is the more reactive metal.

Suggest why the student is wrong.

Francium is the most reactive metal in Group I.

Predict what would be observed if a small piece of francium were added to cold water.