Group 7 (Edexcel GCSE Combined Science: Chemistry): Exam Questions

A chlorine atom contains 17 electrons, 18 neutrons and 17 protons.

i) State the mass number of this chlorine atom. (1)

ii) Give the electronic configuration of this chlorine atom. (1)

Describe what you would see if damp, blue litmus paper is placed into chlorine gas.

Chlorine exists as diatomic molecules. In a molecule, two chlorine atoms are joined by a covalent bond.

i) Describe what is meant by a covalent bond. (2)

ii) Explain why chlorine is a gas, rather than a liquid, at room temperature. (3)

When the gas hydrogen chloride, HCl, is dissolved in water, a solution forms. Blue litmus paper dipped in this solution turns red.

State why the litmus paper turns red.

i) Figure 13 lists the halogens in the order in which they appear in group 7 of the periodic table.

The melting points of four of the halogens are given.

Figure 13

Estimate the melting point of iodine.

(1)

........................ °C

ii) Bromine reacts with heated iron.

Give the name of one halogen that would react with iron more vigorously than bromine.

(1)

A student carried out a displacement reaction using an unknown halogen and a salt containing a halide ion.

As the reaction progressed they observed the formation of a dark brown solution.

Which halogen and salt did the students react together?  

The boiling point of the halogens increases down Group 7.

Which statement explains why?

Complete the following sentences.

i) The name given to group 7 in the periodic table is ............................................... .

(1)

ii) The name given to group 0 in the periodic table is ............................................... .

(1)

Which of the following rows gives the colours of the group 7 elements chlorine and bromine at room temperature?

Figure 2 shows the melting and boiling points of bromine and iodine. 

Figure 2

 Using the information in Figure 2, which row shows the physical states of these elements at 50°C? 

The densities of some elements in group 0 are shown in Figure 3.

 
Figure 3

Use the information in Figure 3 to suggest the density of krypton.

For many years, argon was used to fill filament light bulbs.
A filament light bulb is shown in Figure 4.

 Figure 4

 When the bulb is in use the metal filament becomes extremely hot. 

Explain why argon, rather than air, was used to fill filament light bulbs.

Higher Only

Chlorine reacts with potassium iodide to form potassium chloride and iodine. 

Cl₂ (g)    +    2KI (aq)        →      2KCl (aq)     +     I₂ (aq)

Which species has been reduced? 

Fluorine, chlorine, bromine, iodine and astatine are elements in group 7.

Describe the test to show that a gas is chlorine.

Bromine reacts with hydrogen to form hydrogen bromide. Hydrogen bromide dissolves in water to form a solution.

State the name of the solution formed.

There is a trend in the colour and the state of the halogens at room temperature. 

Predict the colour and state of astatine at room temperature. 

colour ..............................

state ..............................

Bromine, chlorine and iodine are dissolved in water to make aqueous solutions. Potassium iodide solution is added to each of these solutions.

Figure 6 shows the observations.

Figure 6

Explain the observations shown in the table.

Fluorine reacts vigorously with iron to produce iron(III) fluoride, FeF₃.

Write the balanced equation for this reaction.

Which test is used to confirm the presence of chlorine gas during a reaction?

Fluorine, chlorine, bromine and iodine are elements in group 7 of the periodic table.

i) State the name given to the group 7 elements.

(1)

ii) Name one other element that is in group 7. Use the periodic table on the back of this exam paper to help you.

(1)

iii) Which element is liquid at room temperature and pressure?

(1)

iv) Which element is dark-grey in colour at room temperature and pressure?

(1)

Tin reacts with chlorine to form tin chloride. A sample of tin chloride contains 1.19 g of tin and 1.42 g of chlorine.

Calculate the empirical formula of this tin chloride. (relative atomic masses: Cl = 35.5, Sn = 119.0) You must show your working.

Tin also reacts with fluorine. The reaction between fluorine and tin is much more vigorous than the reaction between chlorine and tin.

Figure 8 shows the electronic configurations of fluorine and chlorine.

Figure 8

Explain, in terms of their electronic configurations, why fluorine reacts with tin more vigorously than chlorine reacts with tin.

Bromine can react with hydrogen to form hydrogen bromide. 

Which statement is not true about hydrogen bromide? 

This question is about some of the elements in group 7 of the periodic table.

Which row in the table correctly shows the colours and physical states of the elements at room temperature?

The compound phosphorus oxychloride has the formula POCl₃.

Calculate the percentage by mass of chlorine in phosphorus oxychloride. (relative atomic masses: O = 16.0, P = 31.0, Cl = 35.5)

percentage by mass of chlorine = .......................................

Higher Only

When iron reacts with chlorine, iron chloride is formed. Two possible equations for this reaction are

A      Fe + Cl₂→ FeCl₂

B      2Fe + 3Cl₂→ 2FeCl₃

In an experiment, 8.40 g iron reacts with chlorine to form 19.05 g iron chloride.

Show, using a calculation, which reaction, A or B, is taking place. You must show your working.
(relative atomic masses: Cl = 35.5, Fe = 56.0)

Group 1 metals react with the elements from group 7 to form salts.

Some examples of these reactions are shown in Figure 10.

Figure 10

You will find the position of these elements in their groups on the periodic table.

Explain, in terms of their electronic configurations and the relative reactivity of these elements, which of the reactions shown in Figure 10 would be the most violent.

A student adds some drops of bromine water to a solution of potassium iodide. 

Which statement is correct?