Chemical bonds

Sodium chloride is an ionic compound.

Sodium chloride is made from sodium ions, Na +, and chloride ions, C l –. (a)

Fig. 13.1 shows a model for the ionic lattice of sodium chloride.

Complete by writing in the missing sodium ions, Na +, and chloride ions, C l –. Fig. 13.1

Fig. 13.1

What is the formula of sodium chloride?

Sodium chloride can be split up into its elements using electrolysis.

During electrolysis, sodium chloride must be heated until it is a liquid.

The table shows the melting point and boiling point of sodium chloride.

Suggest a temperature that sodium chloride should be heated to so it is a liquid.

Fig. 13.2 shows a diagram for the electrolysis of molten sodium chloride.

Fig. 13.2

What is the name of the piece of equipment, X ?

Name the gas produced at the anode.

A student thinks that the electrodes (anode and cathode) should be inert and made from graphite.

Complete the sentences to explain why the student is correct.

Graphite is reactive / unreactive. It is an electrical conductor / electrical insulator.

Sodium chloride contains 39% sodium.

Calculate the mass of sodium that is produced from the electrolysis of 160 kg of sodium chloride.

Give your answer to 2 significant figures.

* Fig. 13.3 shows the dot and cross diagram for sodium chloride.

Fig. 13.3

Sodium atom Chlorine atom Sodium ion Chloride ion

Explain how sodium and chlorine atoms form sodium and chloride ions.

Use information:

• from Fig. 13.3

• your knowledge of chemical bonding

• ideas about the electron arrangement in the atoms and ions.

Atoms are made up of protons, neutrons and electrons.

The table shows the relative mass and relative charge for a proton and electron.

Complete the table to show the relative mass and relative charge of a neutron.

Use numbers from the list.

The mass of a proton is 1.67 × 10^–27 kg. (b)

An electron is 0.0005 times lighter than a proton.

Calculate the mass of an electron in kg.

Give your answer in standard form.

The symbol for an atom of nitrogen is:

The table shows the number of protons in this atom of nitrogen.

Complete the table by writing in the number of neutrons and number of electrons.

Nitrogen reacts with hydrogen to form ammonia, NH₃.

This is the equation for the reaction.

What is the missing number that balances the equation?

Tick (✓) one box.

Calculate the relative formula mass, M_r, of ammonia, NH₃.

Relative atomic masses (A_r): H = 1 N = 14

A student thinks that the empirical formula of ammonia is NH₃.

Explain why the student is correct.

Tick (✓) one box.

Fig. 14.1 shows the ball and stick model for a molecule of ammonia.

Fig. 14.1

Which statements about a ball and stick model are true, and which are false ?

Tick (✓) one box in each row.

Fig. 14.2 shows the structure of a molecule of ammonia.

Fig. 14.2

Complete the dot and cross diagram for a molecule of ammonia.

Only show the outer shell electrons.

The properties of materials depend on their structure and bonding.

The table shows some information about four materials.

Draw four lines to connect each material with its correct structure.

Ethene, C₂H₄, has this structure.

Complete the dot and cross diagram for a molecule of ethene.

Only show the outer shell electrons.

Explain why ethene has a low boiling point.

Use ideas about structure and bonding.

The equation shows how ethene can be produced.

The table shows some bond energies.

Calculate the total energy transferred to break all the bonds in the reactant.

Energy transferred to break all the bonds =........ kJ / mol

Calculate the total energy transferred to make all the bonds in the products.

Energy transferred when all the bonds are made =........ kJ / mol

Use your answers to parts (i) and (ii) to calculate the energy change for the reaction.

Energy change =........ kJ / mol

Lithium reacts with oxygen to form lithium oxide.

The symbols for lithium and oxygen on the Periodic Table are:

Explain how the positions of lithium and oxygen in the Periodic Table are used to decide that lithium is a metal and oxygen is a non-metal.

Use the Periodic Table on the Data Sheet.

Lithium reacts with oxygen to make lithium oxide.

Complete the balanced symbol equation for the reaction.

Write the electron arrangement for an atom of lithium.

A student thinks that sodium reacts in a similar way to lithium.

Explain why they are correct.

Use the Periodic Table on the Data Sheet.

Lithium can exist as two isotopes.

Explain what isotope means.

Lithium can be added to aluminium to make an alloy. One alloy contains 2% lithium.

A student draws a diagram of the alloy.

Calculate the percentage of lithium atoms in the alloy drawn by the student.

Suggest a reason why the student’s diagram is incorrect.

Lithium reacts with oxygen to form lithium oxide.

The symbols for lithium and oxygen on the Periodic Table are:

Explain how the positions of lithium and oxygen in the Periodic Table are used to decide that lithium is a metal and oxygen is a non-metal.

Use the Periodic Table on the Data Sheet.

Lithium reacts with oxygen to make lithium oxide.

Complete the balanced symbol equation for the reaction.

Write the electron arrangement for an atom of lithium.

When an atom of lithium reacts with oxygen it forms a lithium ion, Li +. (d)

Describe how an atom of lithium forms a lithium ion.

A student thinks that sodium reacts in a similar way to lithium.

Explain why they are correct.

Use the Periodic Table on the Data Sheet.

Lithium can exist as two isotopes.

Explain what isotope means.

Lithium can be added to aluminium to make an alloy. One alloy contains 2% lithium.

A student draws a diagram of the alloy.

Calculate the percentage of lithium atoms in the alloy drawn by the student.

Suggest a reason why the student’s diagram is incorrect.

Fig. 11.1 shows the particle model for an element.

Fig. 11.1

Solid Liquid Gas

Complete Fig. 11.1 by drawing in the particles of the element when it is a gas.

Describe how the particles of the element move in a solid.

Name the change of state labelled X on Fig. 11.1.

The table shows the state of the element chlorine at three different temperatures.

Use the information in the table to estimate the melting point of chlorine.

Tick (✓) one box.

A particle of chlorine has the formula Cl₂.

Fig. 11.2 shows some of the outer electrons in a particle of chlorine.

Fig. 11.2

Complete Fig. 11.2 by drawing in the missing outer electrons.

Complete the sentences about the bonding in a particle of chlorine.

The particles of chlorine are called isotopes / molecules / polymers.

The atoms of chlorine are joined together by a covalent / ionic / metallic bond.

Which test is used to identify chlorine?

Tick (✓) one box.

Atoms of the same element can have different structures.

Fig. 15.1 shows the structure of two different atoms, Y and Z, of the same element.

Fig. 15.1

What name is given to different atoms of the same element such as Y and Z ?

Write the number of protons, neutrons and electrons in an atom of Z.

Write the mass number of an atom of Z.

Write the name of the element that contains atoms of Y and Z.

Use the Periodic Table.

Complete Fig. 15.2 to show the arrangement of electrons in the ions.

What is the formula of the ionic compound formed when atoms of sodium react with atoms of Y ?

Tick (✓) one box.

Why does sodium react with Y and Z in a similar way?

Tick (✓) one box.

The ionic compound formed in Fig. 15.2 has a high melting point.

Explain why. Use ideas about structure and bonding.

Atoms of the same element can have different structures.

Fig. 11.1 shows the structure of two different atoms, Y and Z, of the same element.

Fig. 11.1

What name is given to different atoms of the same element such as Y and Z ?

Write the number of protons, neutrons and electrons in an atom of Z.

Write the mass number of an atom of Z.

Write the name of the element that contains atoms of Y and Z.

Use the Periodic Table.

Complete Fig. 11.2 to show the arrangement of electrons in the ions.

What is the formula of the ionic compound formed when atoms of sodium react with atoms of Y ?

Tick (✓) one box.

Why does sodium react with Y and Z in a similar way?

Tick (✓) one box.

The ionic compound formed in Fig. 11.2 has a high melting point.

Explain why. Use ideas about structure and bonding.

Diamond and graphite are different forms of the same element.

The diagrams show the structures of diamond and graphite.

Describe and explain one property of graphite that is different from diamond.

Describe and explain one property that is similar for both diamond and graphite.

A student thinks that the models used to represent diamond and graphite have limitations.

Give one reason why they are correct.

Complete each sentence to describe the formation of nitrogen dioxide.

Use the words or phrases in the list.

The molecules of nitrogen and oxygen........

The atoms then........ to form nitrogen dioxide.

This is called a........

The equation shows the formation of nitrogen dioxide.

Complete the balanced symbol equation for the reaction.

Use Fig. 11.1.

The table shows the melting point and boiling point of pure nitrogen dioxide.

Which state symbol shows the physical state of nitrogen dioxide at –2 °C?

Tick (✓) one box.

A scientist measures the melting point of a sample of nitrogen dioxide.

The result shows that the sample of nitrogen dioxide is impure.

Which temperature could be the melting point of the impure nitrogen dioxide?

Tick (✓) one box.

A molecule of nitrogen dioxide has the formula NO₂.

Calculate the relative formula mass for nitrogen dioxide.

Relative atomic mass (A_r): N = 14.0 O = 16.0

Nitrogen dioxide is made from the reaction of nitrogen with oxygen.

Fig. 11.2 shows the bonding in a molecule of oxygen, O₂.

Fig. 11.2

Fig. 11.3 shows an incomplete dot and cross diagram for oxygen.

Fig. 11.3

Complete Fig. 11.3 to show the arrangement of the electrons in a molecule of oxygen.

Fullerenes are allotropes of carbon that have many uses.

Fig. 15.1 shows a molecule of a fullerene.

Fig. 15.1

Which group of allotropes contain this fullerene?

Tick one (✓) box.

The carbon atoms in fullerenes are joined by covalent bonds.

Explain how two atoms of carbon form a covalent bond.

How many covalent bonds does one atom of carbon form in a molecule of fullerene, as shown in Fig. 15.1 ?

The model used to show the molecule of fullerene in Fig. 15.1 has limitations.

The table shows some statements about the model.

Which statements about this model are true, and which are false ?

Tick (✓) one box in each row.

Fullerenes can be used as lubricants. Lubricants reduce the friction between moving parts.

Fig. 15.2 shows a lubricant being sprayed onto the chain of a motorbike.

Fig. 15.2

Explain why fullerenes can be used as lubricants.

Use ideas about the structure and bonding of the fullerene shown in Fig. 15.1 in your answer.

A lubricant may need to be used at high temperatures.

Explain why fullerenes can be used at high temperatures.

Use ideas about the structure and bonding of the fullerene shown in Fig. 15.1 in your answer.

Fullerenes are allotropes of carbon that have many uses.

Fig. 11.1 shows a molecule of a fullerene.

Fig. 11.1

Which group of allotropes contain this fullerene?

Tick one (✓) box.

The carbon atoms in fullerenes are joined by covalent bonds.

Explain how two atoms of carbon form a covalent bond.

How many covalent bonds does one atom of carbon form in a molecule of fullerene, as shown in Fig. 11.1 ?

The model used to show the molecule of fullerene in Fig. 11.1 has limitations.

The table shows some statements about the model.

Which statements about this model are true, and which are false ?

Tick one (✓) box in each row.

Fullerenes can be used as lubricants. Lubricants reduce the friction between moving parts.

Fig. 11.2 shows a lubricant being sprayed onto the chain of a motorbike.

Fig. 11.2

Explain why fullerenes can be used as lubricants.

Use ideas about the structure and bonding of the fullerene shown in Fig. 11.1 in your answer.

A lubricant may need to be used at high temperatures.

Explain why fullerenes can be used at high temperatures.

Use ideas about the structure and bonding of the fullerene shown in Fig. 11.1 in your answer.

Potassium chloride, KC l, is an ionic compound.

It is made from potassium ions, K +, and chloride ions, C l –.

Explain why potassium is found in Group 1 of the Periodic Table.

Use ideas about the arrangement of electrons in an atom of potassium.

Explain how an atom of potassium reacts with an atom of chlorine to make potassium chloride.

A student electrolyses potassium chloride.

The diagram shows the equipment they use.

Describe and explain two ways the student could change the experiment to make it work.

In the successful electrolysis of potassium chloride, potassium is made at the cathode.

Explain how potassium atoms are made from potassium ions.

Calcium is a metal found in Group 2 of the Periodic Table.

Draw the arrangement of electrons in an atom of calcium.

Calcium is a metal which can conduct electricity.

Describe the structure and bonding in a metal and explain why metals can conduct electricity.

You can include a diagram in your answer.

Calcium reacts with water to form a solution of calcium hydroxide, Ca(OH)₂, and hydrogen.

Write the balanced symbol equation for the reaction of calcium with water.

Include state symbols in your equation.

A solution of calcium hydroxide is also called limewater.

Name the gas limewater is used as a test for.

Calculate the number of moles in 1.88 g of calcium hydroxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): H = 1.0 O = 16.0 Ca = 40.1

Use your answer to part (d)(i) to calculate the concentration of calcium hydroxide in the solution formed.

Give your answer in mol / dm³.

Concentration of solution =........ mol / dm³

A student adds an excess of dilute hydrochloric acid, HC l, to a solution of calcium hydroxide, Ca(OH)₂.

Write the balanced ionic equation for the reaction of dilute hydrochloric acid and a solution of calcium hydroxide.

Describe and explain how the pH of the solution of calcium hydroxide changes as the dilute hydrochloric acid is added until it is in excess.

The diagram shows the ‘ball and stick’ model for an ionic compound.

Which statement about the ‘ball and stick’ model is correct?

A It shows all the forces between the ions.

B It shows the arrangement of the ions.

C It shows the charges on the ions.

D It shows the sizes of the ions.

Complete the balanced symbol equation for the reaction of sodium and chlorine to make sodium chloride.

Sodium chloride has a high melting point.

Explain why.

Use ideas about the structure and bonding in sodium chloride in your answer.

Write in the table the state symbol for the solution of sodium chloride.

Tick (✓) one box in each column of the table to show if solid sodium chloride and a

solution of sodium chloride conduct electricity.

Complete the table by writing in the explanation for the student’s results.

Use ideas about the structure and bonding in sodium chloride in your answer.

The diagram shows the ‘ball and stick’ model for an ionic compound.

Which statement about the ‘ball and stick’ model is correct?

A It shows all the forces between the ions.

B It shows the arrangement of the ions.

C It shows the charges on the ions.

D It shows the sizes of the ions.

Carbon dioxide, CO₂, is a covalently bonded molecule.

Explain what is meant by a covalent bond.

Look at the diagram. It shows the structure of carbon dioxide.

Complete the dot and cross diagram for carbon dioxide.

The equation shows the formation of 1 mole of carbon dioxide from carbon monoxide and oxygen.

The table shows the bond energies of some bonds.

Calculate the energy change for the formation of 1 mole of carbon dioxide.

Energy change =........ kJ / mol

Explain the term activation energy.

Look at your calculation in (c).

Suggest a value for the activation energy for the formation of 1 mole of carbon dioxide in this reaction.

Table 14.1 shows the melting points of some of the Group 1 metals.

Plot the data in Table 14.1 on the grid in Fig. 14.1.

Draw a line of best fit.

Describe the relationship between the atomic number of the Group 1 metals and their melting points shown in Fig. 14.1.

Describe the metallic bonding in sodium.

Use information from Fig. 14.2 in your answer.

Look at the melting points of sodium and lithium in Table 14.1.

Suggest a reason for the difference in their melting points.

Atoms are made of particles called protons, neutrons and electrons.

Complete the table to show the relative charges of protons, neutrons and electrons.

Sodium is a metal in the Periodic Table.

Sodium is an example of an atom that can form an ion.

Describe what happens to a sodium atom when it becomes an ion.

Look at this statement about the Periodic Table.

‘Atoms are placed in groups according to the total number of electrons they have.’

Explain why this statement is incorrect.

A new element has been discovered and has these properties:

• a high melting point

• reacts with oxygen to form oxides

• conducts electricity

• solid at room temperature.

Suggest what type of bonding the new element has.

Explain your answer.

What is the melting point of substance X ?

What is the state of matter of substance X at 70 °C?

Tick (✓) one box.

In which state of matter do the particles of X have the most energy?

Tick (✓) one box.

Another substance, Y, is heated.

Substance Y is an ionic compound.

Substance Y has a much higher melting point than substance X.

Substance X is a simple covalent compound.

Which substance, X or Y, is made up of molecules ?

Tick (✓) one box.

Explain your answer.

Explain the difference between the melting points of substances X and Y.

Use ideas about the forces between the particles.

A student investigates three reactions.

She wants to find out if the reactions are exothermic or endothermic.

Look at her results.

Which reaction, X, Y or Z, is endothermic ?........

Explain your answer.

Draw a labelled reaction profile for an endothermic reaction.

Use the following labels on your reaction profile:

• products

• energy change

• activation energy.

Another student repeats the same reactions.

The student does the experiment in a polystyrene cup instead of a beaker.

Explain why using a polystyrene cup is an improvement to the method.

The reaction between iron oxide and aluminium is very exothermic.

Look at the equation for the reaction.

During this reaction the aluminium is oxidised.

Explain what is meant by the term oxidised.

Pure iron metal is produced in the reaction.

Draw a diagram to show the bonding in a metal.

Label your diagram clearly.

Which diagram correctly shows the bonding in a molecule of hydrogen fluoride?

A student investigates three reactions.

She wants to find out if the reactions are exothermic or endothermic.

Look at her results.

Which reaction, X, Y or Z, is endothermic ?........

Explain your answer.

Draw a labelled reaction profile for an endothermic reaction.

Use the following labels on your reaction profile:

• products

• energy change

• activation energy.

Another student repeats the same reactions.

The student does the experiment in a polystyrene cup instead of a beaker.

Explain why using a polystyrene cup is an improvement to the method.

The reaction between iron oxide and aluminium is very exothermic.

Look at the equation for the reaction.

During this reaction the aluminium is oxidised.

Explain what is meant by the term oxidised.

Pure iron metal is produced in the reaction.

Draw a diagram to show the bonding in a metal.

Label your diagram clearly.