Metallic Bonding (Cambridge (CIE) O Level Chemistry): Exam 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 ..........................................................................................................

The table below shows the elements in the third period of the Periodic Table, the number of electrons in their outer energy  level, their oxidation state in their common compounds and their melting points.

Describe and explain the variation in oxidation state across the period.

The first three elements, Na, Mg and Al, are metals.

Describe the structure of a typical metal.

Explain why Na, Mg and Al are good conductors of electricity.

Which element exists as diatomic molecules of the type X₂?

Silicon has a similar structure to diamond.

Explain why silicon has the highest melting point in the period.

Sodium chloride is a crystalline solid with a high melting point. It dissolves in water to give a neutral solution. Phosphorus trichloride is a liquid at room temperature. It reacts with water to form an acidic solution.

Suggest an explanation for these differences in properties.

Describe how you could show that magnesium oxide is a basic oxide and not an amphoteric oxide.

Draw a dot-and-cross diagram showing the bonding in magnesium oxide. Show outer electrons only.

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.

This substance is an ionic solid. 

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.

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

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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 ........................................................................

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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?

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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.

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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.

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

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