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CAIE A-Level Chemistry 9.2 Period 3 Chemical Property Trends

Practise equations and explanations for Period 3 elements, oxides and chlorides, including acid–base behaviour.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • write balanced reactions of selected Period 3 elements with oxygen, chlorine and water
  • track maximum oxidation number across specified oxides and chlorides using valence electrons
  • explain oxide and chloride reactions with water, acids or bases through bonding and electronegativity

Covered syllabus points

9.2.1—Reactions of the elements with oxygen (to9.2.2—The variation in the oxidation number9.2.3—Reactions/equations: the reactions, if any,9.2.4—Reactions/equations: the acid / base behaviour9.2.5—Reactions of the chlorides NaCl, MgCl2, Al9.2.6—Variations and trends in 9.2.2, 9.2.3, 9.2.49.2.7—Suggest the types of chemical bonding present

9.2 Periodicity of chemical properties of the elements in Period 3 question 1

[Maximum number: 3]

The Group 17 elements are oxidising agents.

Question (a)

(a)

Write an equation to show the reaction in which Cl2\mathrm{Cl}_{2} oxidises aluminium metal.

[ 1 ]

Question (b)

(b)

Table 1.3 gives some information about MgCl2\mathrm{MgCl}_{2} and SiCl4\mathrm{SiCl}_{4}.

Table 1.3

Table 1.3

[ 2 ]

Question (i)

(i)

Suggest the pH of the solutions that form when each chloride is added to water.
MgCl2\mathrm{MgCl}_{2}SiCl4\mathrm{SiCl}_{4}

[ 2 ]

9.2 Periodicity of chemical properties of the elements in Period 3 question 2

[Maximum number: 6]

Oxygen is a Group 16 element.

Question (a)

(a)

Write equations for the following reactions.
- sodium and oxygen
- sulfur and oxygen

[ 2 ]

Question (b)

(b)

The maximum oxidation state of the Period 3 elements in their oxides varies across the period.

State and explain the variation.

[ 2 ]

Question (c)

(c)

H2O\mathrm{H}_{2} \mathrm{O} reacts with both inorganic and organic compounds.

[ 2 ]

Question (i)

(i)

Complete Table 2.1 to give details of the reactions of some Period 3 oxides with H2O\mathrm{H}_{2} \mathrm{O}.

Table 2.1

Table 2.1

[ 2 ]

9.2 Periodicity of chemical properties of the elements in Period 3 question 3

[Maximum number: 2]

The Pauling electronegativity values of elements can be used to predict the chemical properties of compounds.

Use the information in Table 1.1 to answer the following questions.

Table 1.1

Table 1.1

Question (a)

(a)

CO2\mathrm{CO}_{2} and SO2\mathrm{SO}_{2} are acidic gases.

[ 2 ]

Question (i)

(i)

Write an equation for the reaction of SO2\mathrm{SO}_{2} with H2O\mathrm{H}_{2} \mathrm{O}.

[ 1 ]

Question (ii)

(ii)

Write an equation for the reaction of SO2\mathrm{SO}_{2} with NaOH .

[ 1 ]
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