Covalent bonding

Lithium, carbon, nitrogen, fluorine and neon are elements in the same row of the periodic table.

What is the chemical symbol of lithium?

Use the periodic table.

Lithium has metallic bonding.

Which electrons are involved in metallic bonding?

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Lithium reacts with fluorine to produce lithium fluoride.

Draw one line from each substance to the particle diagram that represents the substance.

Table 2 shows the electrical conductivity of three substances.

Lithium fluoride is an ionic compound.

Which substance is lithium fluoride?

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Carbon can exist in different forms.

Figure 4 represents one form of carbon.

What is the name of the form of carbon in Figure 4 ?

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Carbon and fluorine form a compound with the formula CF₄

Calculate the relative formula mass (M_r) of CF₄

Relative atomic masses (A_r): C = 12 F = 19

Figure 5 represents a molecule of nitrogen.

What is the total number of shared electrons in the covalent bond shown in Figure 5 ?

Lithium and nitrogen form a compound with the formula Li₃N

Complete the sentence.

Choose the answer from the box.

Neon does not react with other elements to form compounds.

Why is neon unreactive?

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This question is about hydrogen chloride (HC l) and hydrogen chlorate (HOC l).

Hydrogen chloride and hydrogen chlorate both form acids when dissolved in water.

Hydrogen chloride gas dissolves in water to form hydrochloric acid.

Give the state symbols for:

• hydrogen chloride

• water

• hydrochloric acid.

A solution of hydrochloric acid has:

• a concentration of H⁺ ions of 3.16 × 10⁻³ mol/dm³.

What is the concentration of H⁺ ions in a solution of hydrochloric acid that has a pH of 3.5?

Figure 5 shows the outer shells in one molecule of hydrogen chlorate (HOC l).

Complete the dot and cross diagram to show the electrons in the outer shells.

Figure 5

Hydrogen chlorate dissolves in water to form a weak acid.

Explain why a weak acid has a higher pH than a strong acid of the same concentration.

Hydrogen chloride is produced in the reaction between methane and chlorine.

Figure 6 represents the equation for the reaction.

Table 4 shows the bond energies.

Calculate the overall energy change for the reaction.

Carbon is in Group 4 of the periodic table.

Methane contains carbon and hydrogen atoms.

A carbon atom has 4 electrons in the outer shell.

A hydrogen atom has 1 electron in the outer shell.

Complete the dot and cross diagram for a methane molecule.

Which diagram represents the structure of diamond?

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Figure 3 represents part of the structure of graphite.

In graphite each carbon atom forms covalent bonds.

How many covalent bonds does each carbon atom form in graphite?

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Graphite conducts electricity.

Which particles carry electrical charge through graphite?

Figure 4 represents the structure of a fullerene.

Where are fullerenes used?

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Describe the structure of the fullerene shown in Figure 4.

Nitrogen reacts with hydrogen to produce ammonia (NH₃).

Complete the dot and cross diagram for an ammonia molecule.

The equation for the reaction between nitrogen and hydrogen to produce ammonia is:

Calculate the mass of hydrogen that is needed to produce 25 g of ammonia.

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

Figure 7 shows the displayed formulae equation for the reaction of nitrogen

with hydrogen.

In the reaction the energy released forming new bonds is 93 kJ/mol greater than the energy needed to break existing bonds.

Table 3 shows bond energies.

Calculate the bond energy X for the H — H bond.

Use Figure 7 and Table 3.

Energy is released from the reaction to produce ammonia.

Figure 8 shows part of the reaction profile for the reaction between nitrogen and hydrogen to produce ammonia.

Complete Figure 8.

You should:

• complete the profile line

• label the energy level of the reactants and the product

• label the overall energy change.

Structure and bonding is used to explain properties of compounds.

Metal atoms react with non-metal atoms to form ions.

Which group of elements does not form ions? Tick (✓) one box.

Potassium reacts with chlorine to produce potassium chloride (KC l). Figure 6 shows what happens to the electrons in the outer shells when a potassium atom reacts with a chlorine atom.

Describe what happens when a potassium atom reacts with a chlorine atom to produce potassium chloride. Answer in terms of electrons.

In solid ionic compounds, oppositely charged ions attract to form a giant structure. Which structure represents the arrangement of ions in solid potassium chloride? Tick (✓) one box.

Non-metal atoms share electrons to form covalent bonds.

Water (H₂O) is a covalent molecule. Table 2 shows the number of electrons in the outer shells of hydrogen atoms and

Figure 7 shows part of a dot and cross diagram for a molecule of water. Complete the dot and cross diagram. You should only show electrons in the outer shells.

Figure 7

Silica has a giant covalent structure. Figure 8 represents the structure of silica.

Determine the ratio of silicon (Si) atoms to oxygen (O) atoms in silica. Use Figure 8.

Polymers have very large molecules. Figure 9 represents part of the structure of a polymer.

What holds polymer molecule 1 and polymer molecule 2 together in a polymer? Tick (✓) one box.

Describe the trend shown in Figure 10.

Group 7 elements are known as the halogens. All atoms of Group 7 elements contain protons, neutrons and electrons.

What is the order of discovery of the proton, neutron and electron? Tick (✓) one box.

Table 1 shows the mass of a proton and of an electron.

Calculate how many times heavier a proton is than an electron.

A bromine atom can be represented as⁸¹₃₅Br.

What is the number of neutrons in this bromine atom?

What is the number of electrons in a bromide ion ?

Chlorine has two isotopes. Table 2 shows the percentage abundance of the two isotopes of chlorine.

Calculate the relative atomic mass (A_r) of chlorine.

Figure 4 shows the outer shells in one molecule of chlorine (Cl₂). Complete the dot and cross diagram to show the electrons in the outer shells.

This question is about hydrogen chloride and sodium hydroxide.

A chlorine atom has 7 electrons in the outer shell. A hydrogen atom has 1 electron in the outer shell. Figure 4 represents part of a dot and cross diagram for a molecule of hydrogen chloride.

Complete the dot and cross diagram. Use dots (ο) and crosses (x) to represent electrons. You should show only the electrons in the outer shells.

Hydrogen chloride dissolves in water to produce hydrochloric acid. Hydrochloric acid reacts with sodium hydroxide solution. Complete the word equation for the reaction between hydrochloric acid and sodium hydroxide.

hydrochloric acid + sodium hydroxide → + water

Solutions of hydrochloric acid and sodium hydroxide are reacted and the temperature change is recorded.

In the reaction, 3.65 g of hydrogen chloride reacts with 4.00 g of sodium hydroxide. 1.80 g of water is produced. Calculate the mass of the other product.

Figure 5 shows part of the thermometer used to measure the temperature.

What is the temperature reading on the thermometer?

In the reaction, the temperature increases. What type of reaction is happening when the temperature increases?

Sodium hydroxide is an alkali. Which two ions are in sodium hydroxide solution? Tick (✓) two boxes.

This question is about hydrogen chloride and hydrochloric acid.

Complete the dot and cross diagram to represent the bonding in hydrogen chloride on Figure 7. Use dots (o) and crosses (x) to represent electrons. You should show only the electrons in the outer shells.

Hydrogen chloride dissolves in water to produce hydrochloric acid. Hydrochloric acid is a strong acid. What is meant by the term strong acid?

Describe how magnesium can be used to distinguish between a strong acid and a weak acid of the same concentration.

The concentration of hydrochloric acid is increased by a factor of 100 What is the change in pH?

Ethene and hydrogen chloride react to produce chloroethane. The displayed formulae equation for the reaction is:

The reaction is exothermic. In the reaction the energy released forming new bonds is 56 kJ/mol greater than the energy needed to break existing bonds. Table 1 shows some bond energies.

Calculate the bond energy X.

This question is about oxygen and compounds of oxygen.

What is the state symbol of oxygen at room temperature?

Figure 4 shows the percentage by mass of the elements calcium, carbon and oxygen in calcium carbonate.

What is the percentage by mass of calcium in calcium carbonate?

At high temperature, sodium nitrate decomposes into sodium nitrite and oxygen. A student heats three samples of sodium nitrate. The mass of each sample was 4.50 g The mass of solid after heating was recorded. Table 2 shows the mass of solid after heating in each experiment.

Calculate the mean mass of solid after heating. Give your answer to 3 significant figures.

Table 3 shows the electronic structure of hydrogen and oxygen.

Figure 5 shows part of a dot and cross diagram of a molecule of water (H₂O). Complete the dot and cross diagram. You should show only the electrons in the outer energy levels.

Oxygen and sulfur are examples of simple molecules.

Complete the sentence. Choose the answer from the box.

Figure 6 shows the relative sizes of an oxygen molecule and a sulfur molecule.

How does the boiling point of sulfur compare with the boiling point of oxygen? Complete the sentences.

than the intermolecular forces in oxygen.

This question is about oxygen.

Hydrogen reacts with oxygen.

Figure 2 shows the relative energies of the reactants and products at a certain temperature.

Label the activation energy on Figure 2.

Determine the overall energy change for the reaction between hydrogen and oxygen shown in Question 03.1 Use Figure 2.

Oxygen is in Group 6 of the periodic table. Figure 3 shows the outer energy levels in one molecule of oxygen (O₂). Draw the electrons in the outer energy levels in Figure 3.

The equation shows the decomposition of hydrogen peroxide. 2 H – O – O – H → 2 H – O – H + O=O Table 1 shows the bond energies.

Calculate the overall energy change for the reaction.

This question is about sodium.

Sodium reacts with chlorine. What is the balanced equation for the reaction?

Tick (✓) one box.

Hot sodium is put in a gas jar of chlorine. Describe the observations made before, during and after the reaction.

Explain why sodium is less reactive than potassium.

Chlorine reacts with sodium and with hydrogen. Compare the structure and bonding in sodium chloride and hydrogen chloride.

This question is about structure and bonding.

Figure 1 shows part of the structure of calcium oxide (CaO).

What type of bonding is present in calcium oxide?

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02

Figure 2 shows a particle of methane (CH₄).

What type of particle is present in Figure 2 ?

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Figure 3 shows the structure of C₆₀

Complete the sentence. Choose the answer from the box.

Figure 4 shows the structure of graphite.

What type of bond is labelled A in Figure 4 ? Tick one box.

In graphite, each carbon atom forms bonds with other carbon atoms as shown in

Figure 4

How many electrons does one carbon atom use to form one bond? Tick one box.

An electric current is passed through copper. Figure 5 shows the apparatus used.

Complete the sentence. Choose the answer from the box.

Complete the sentence. Choose the answer from the box.

Figure 6 shows the apparatus used to investigate the effect of electricity on sodium chloride solution.

Complete the sentence. Choose the answer from the box.

Sodium chloride is made up of ions. Figure 7 shows the apparatus used to investigate the effect of electricity on solid sodium chloride and molten sodium chloride.

Table 1 shows the results.

Draw one line from each statement to the correct reason.

This question is about the halogens.

Write the state symbol for chlorine at room temperature.

Figure 4 represents one molecule of fluorine. Complete the dot and cross diagram on Figure 4 You should show only the electrons in the outer shells.

19 A fluorine atom can be represented as 9 F What is the total number of electrons in a fluorine molecule (F₂)? Tick one box.

Aluminium reacts with bromine to produce aluminium bromide. Complete the balanced chemical equation for this reaction.

When chlorine reacts with potassium bromide, chlorine displaces bromine.

Explain why chlorine is more reactive than bromine.