CIE A Level Chemistry
CIE A Level Chemistry The Periodic Table: Chemical Periodicity Exam Questions
Free CIE A Level Chemistry exam questions for The Periodic Table: Chemical Periodicity, with a mark scheme for every pack. Covers period 3 trends in radius, melting point, conductivity and ionisation energy, and reactions of the elements, oxides and chlorides.
The Periodic Table: Chemical Periodicity exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
StemUp mark scheme flashcards
A-Level Chemistry Flashcards for 2027 Onwards
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Then test yourself with the questions on this page.
From £10.99View flashcards
About CIE A Level Chemistry The Periodic Table: Chemical Periodicity
Chemical periodicity in Cambridge International 9701 focuses on the elements sodium to argon in Period 3. You must explain trends in atomic radius, ionic radius, melting point, electrical conductivity and first ionisation energy in terms of structure and bonding. The topic then covers the reactions of the elements with oxygen, chlorine and water, and the acid-base behaviour of the oxides and hydroxides, including the amphoteric nature of aluminium oxide. The chlorides are studied for their reactions with water. This AS topic builds on atomic structure and chemical bonding, and examiners often ask you to write equations and to deduce the position of an unknown element from its properties.
What you need to know
- Physical trends Atomic radius decreases from Na to Cl as nuclear charge increases with the same shielding. Melting point rises from Na to Si (giant metallic then giant covalent) then falls sharply to P4, S8, Cl2 and Ar (simple molecular).
- Electrical conductivity Conductivity increases from Na to Al as the number of delocalised electrons per atom rises. Si is a semiconductor and the non-metals from P to Ar do not conduct.
- Reactions with oxygen Na burns with a yellow flame to form Na2O, Mg with a bright white flame to MgO, and Al, Si, P and S form Al2O3, SiO2, P4O10 and SO2. Oxidation numbers rise to the group number in the oxides.
- Oxides with water Na2O gives NaOH (pH about 13) and MgO gives slightly alkaline Mg(OH)2 (pH about 9). Al2O3 and SiO2 are insoluble, while P4O10 and SO2 or SO3 form acidic solutions (pH about 2).
- Acid-base behaviour Na2O and MgO are basic, Al2O3 is amphoteric (reacts with HCl and NaOH), and SiO2, P4O10 and SO3 are acidic. SiO2 reacts with hot concentrated NaOH.
- Chlorides with water NaCl dissolves to give a neutral solution and MgCl2 a slightly acidic one. AlCl3, SiCl4 and PCl5 are hydrolysed, releasing HCl fumes, for example SiCl4 + 2H2O → SiO2 + 4HCl.
Common mistakes in The Periodic Table: Chemical Periodicity
- Saying chlorine has a higher melting point than sulfur because of stronger covalent bonds; both are simple molecular and S8 has more electrons so stronger van der Waals forces.
- Describing SiO2 as reacting with water; it is insoluble and the pH stays at 7.
- Forgetting that Al2O3 is amphoteric and needs two equations, one with acid and one with alkali.
- Writing the formula of phosphorus(V) oxide as P2O5 in equations when P4O10 is the molecular formula expected.
- Saying atomic radius decreases across the period because of more electrons; the key factor is increasing nuclear charge with similar shielding.
Try three The Periodic Table: Chemical Periodicity exam-style questions
1. Write equations for the reactions of aluminium oxide with hydrochloric acid and with sodium hydroxide solution. (2 marks)
Show the mark scheme answer
Al2O3 + 6HCl → 2AlCl3 + 3H2O; Al2O3 + 2NaOH + 3H2O → 2NaAl(OH)4.
2. Explain the large difference in melting point between silicon and phosphorus. (3 marks)
Show the mark scheme answer
Silicon is giant covalent (macromolecular); many strong covalent bonds must be broken; phosphorus is simple molecular (P4), only weak van der Waals forces between molecules are overcome.
3. Describe what you would observe when silicon tetrachloride is added to water and give the equation. (2 marks)
Show the mark scheme answer
White fumes (of HCl) and a white solid forms, solution is strongly acidic; SiCl4 + 2H2O → SiO2 + 4HCl.
The Periodic Table: Chemical Periodicity FAQs
What does Cambridge AS & A Level Chemistry Chemical periodicity cover?
It covers Period 3 trends in physical properties and the reactions of the elements, oxides, hydroxides and chlorides, including acid-base behaviour.
How do I revise Period 3 oxides and chlorides?
Make a table with formula, structure, oxidation number, reaction with water and pH for each compound, then practise writing the equations from memory.
Which equations do I need for periodicity?
Reactions of Na, Mg, Al, Si, P and S with oxygen, Na and Mg with water, the oxides with water, Al2O3 with acid and alkali, and the chlorides with water.
