Covalent bonding: Edexcel International A Level Chemistry questions

Every Edexcel International A Level Chemistry exam question on 3B Covalent bonding (specification points 3.10–3.15), 2019–2025, with its mark scheme and examiner’s report.

All 73 questions on Covalent bonding, as a list

June 2025, AS Unit 1, Q8 (1 mark): Which substance does not exist as a giant lattice? A silver (Ag) B sodium chloride (NaCl) C graphite (C) D buckminsterfullerene (C60)
June 2025, AS Unit 1, Q23(b)(i) (1 mark): Describe covalent bonding. (1)
June 2025, AS Unit 1, Q23(b)(ii) (3 marks): Methane, ammonia and water are covalently bonded compounds. Draw the dot-and-cross diagrams for the molecules of methane (CH4), ammonia (NH3) and water (H2O). (
January 2025, AS Unit 1, Q25(b)(i) (2 marks): State what is meant by the term polar molecule and why chlorine is not polar. (2)
January 2025, AS Unit 1, Q26(a) (1 mark): Give the name of the compound S2F10. (1)
January 2025, AS Unit 1, Q26(b) (2 marks): Molecules of S2F10 consist of two SF5 units linked by a S S bond. Complete the dot‑and‑cross diagram of S2F10 , showing the outer shell electrons. Use dots ()
January 2025, AS Unit 1, Q26(c) (2 marks): Draw a dot‑and‑cross diagram of SF4, showing all the outer shell electrons. Use dots () for the sulfur electrons and crosses (×) for the fluorine electrons. (2
October 2024, AS Unit 1, Q20(c)(ii) (3 marks): Explain why the melting temperature of carbon is high, with reference to its structure and bonding. (3)
October 2024, AS Unit 1, Q21(b)(ii) (3 marks): Draw the dot‑and‑cross diagram for Al2Cl6 . Use dots (•) for the electrons of aluminium and crosses (×) for the electrons of chlorine. (3)
October 2024, AS Unit 1, Q21(c) (3 marks): Thallium also forms ions containing chlorine, for example the TlCl4 In this ion, the thallium atom has 10 electrons in its outermost shell. Phosphorus in phosph
October 2024, Unit 5, Q18(b)(i) (2 marks): The dot-and-cross diagram for the thiocyanate ion can be drawn in more than one way. For example, the negative charge can be on the nitrogen atom as shown. – *
June 2024, AS Unit 1, Q17(a) (2 marks): Complete the dot-and-cross diagram by adding all the electrons in the outer shells of the five carbon atoms in a diamond tetrahedral unit. (2) C C C C C
June 2024, AS Unit 1, Q17(b) (2 marks): Draw a labelled 3D structure of graphite, showing two layers of at least 13 carbon atoms each and the forces between the layers. (2)
June 2024, AS Unit 1, Q17(c) (2 marks): Suggest why diamond has a greater density than graphite. (2)
June 2024, AS Unit 2, Q18(a)(i) (2 marks): Complete the dot‑and‑cross diagram for this structure. Use dots (•) for oxygen electrons and crosses (×) for chlorine electrons. (2) Cl O O
June 2024, Unit 4, Q15(a)(i) (2 marks): Complete the table, indicating the type of bonding in the reactants and products of this reaction. (2) Substance SiO2 Mg Mg2Si MgO Bonding type covalent
June 2024 (R), AS Unit 2, Q22(d) (2 marks): Urea, NH2CONH2 , can also be made from ammonia. Complete the dot‑and‑cross diagram for the urea molecule. (2) O C N N H H H H
January 2024, AS Unit 1, Q21(b)(i) (3 marks): Draw a dot‑and‑cross diagram for this molecule. Show outer electrons only. (3)
October 2023, AS Unit 1, Q5 (1 mark): What types of bonding are present in the compound ammonium chloride, NH4Cl? Ionic Covalent Dative covalent A    B    C    D   
October 2023, AS Unit 1, Q16 (1 mark): A cyclic hydrocarbon has the structure shown. How many pi (π) and sigma (σ) bonds are present in the molecule? pi (π) bonds sigma (σ) bonds A 2 11 B 2 5 C 4 3 D
October 2023, AS Unit 1, Q18(c)(i) (1 mark): Draw a dot-and-cross diagram of the molecule, BeCl2. (1)
October 2023, AS Unit 1, Q18(c)(iii) (2 marks): Draw a diagram to show how two beryllium chloride molecules bond together to form the dimer, Be2Cl4, stating the type of bond involved. (2) Type of bond
January 2023, AS Unit 1, Q12 (1 mark): Which is a use of graphene based on its electrical properties? A drill tips B pencils C touch screens D body armour
January 2023, AS Unit 1, Q14 (1 mark): Which molecule is polar? A 1,1‑dibromopropane B E‑1,2‑dibromoethene C hexafluoroethane D tetrachloromethane Use this space for any rough working. Anything you w
January 2023, AS Unit 1, Q23(b)(ii) (2 marks): Nitrogen molecules bind to zeolite using their outer electrons. Draw a dot‑and‑cross diagram of the bonding in a nitrogen molecule. Show outer electrons only. (
January 2023, AS Unit 1, Q25(a)(ii) (2 marks): Aluminium chloride can exist as a dimer formed from two molecules of aluminium trichloride. Draw a diagram of this dimer, showing the bonding between the two mo
January 2023, AS Unit 2, Q20(c)(i) (2 marks): Complete a possible dot-and-cross diagram for N3 Show outer electrons only. (2)   –    N N N       
October 2022, AS Unit 1, Q16(d)(ii) (2 marks): Germane can donate a proton to ammonia, forming the ion GeH3 –. NH3 + GeH4 → NH4 + + GeH3 – –. Show the outer electrons only. Draw a dot‑and‑cross diagram of th
June 2022, AS Unit 1, Q1 (1 mark): Elements in their most stable state exist as A atoms in giant structures only B atoms in molecules and atoms in giant structures only C isolated atoms and atoms
June 2022, AS Unit 1, Q12 (1 mark): At 180 °C, aluminium chloride exists as Al2Cl6 . What is the structure of Al2Cl6 ? − Cl + A Cl Al Cl Cl Al Cl Cl Cl Cl B Cl Al Al Cl Cl Cl Cl Cl Cl C Al Al Cl C
June 2022, AS Unit 1, Q20(c)(i) (2 marks): Draw a dot-and-cross diagram to show the bonding in a molecule of bromine. Only the outer electrons should be shown. (2)
June 2022, AS Unit 1, Q21(a)(i) (2 marks): Describe the covalent bond between a silicon atom and an oxygen atom in silicon dioxide, in terms of the particles involved. (2)
June 2022, AS Unit 1, Q21(a)(ii) (3 marks): Compare and contrast the covalent bonding in carbon dioxide and silicon dioxide in terms of orbital overlap. (3)
June 2022, AS Unit 1, Q21(b)(ii) (2 marks): Explain the polarity of the carbon–oxygen bond. (2)
June 2022, AS Unit 1, Q21(c)(i) (1 mark): Using your knowledge of the structure of diamond, suggest how the structure of silicon dioxide is similar to that of diamond. (1)
June 2022, AS Unit 1, Q21(c)(ii) (1 mark): Give a possible reason why silicon dioxide has a lower melting temperature than diamond, even though the Si O bond is stronger than the C C bond. (1)
January 2022, AS Unit 1, Q22(b)(i) (1 mark): In the elements silicon, phosphorus, sulfur and chlorine, the atoms are joined by covalent bonds. Describe the attraction between the atoms in a covalent bond.
January 2022, AS Unit 1, Q22(b)(ii) (3 marks): Explain why the melting temperature of silicon is much higher than that of phosphorus, by referring to their structures. (3)
January 2022, AS Unit 1, Q22(c)(i) (2 marks): Complete the dot-and-cross diagram of a molecule of sulfur dichloride. Use dots (•) for the chlorine electrons and crosses (×) for the sulfur electrons. Show th
January 2022, Unit 5, Q13(a) (1 mark): Draw a dot‑and‑cross diagram for arsine, AsH3 . (1)
October 2021, AS Unit 1, Q7(b) (1 mark): Ammonium sulfate is used in the preparation of the double salt. What types of bond are present in ammonium sulfate? (1) A ionic only B covalent and ionic only C
October 2021, AS Unit 1, Q12(b) (2 marks): In the gaseous state, beryllium chloride is molecular. Draw a dot-and-cross diagram to show the bonding in a molecule of beryllium chloride, BeCl2 . (2)
October 2021, AS Unit 1, Q12(c) (2 marks): In the solid state, beryllium chloride forms a polymeric structure. The diagram shows part of this structure. Cl Cl Cl Cl Cl Be Be Be Be Cl Cl Cl Cl Cl The diag
October 2021, AS Unit 1, Q13(b) (3 marks): Silicon dioxide, SiO2 , is the main constituent of sand and has a giant lattice structure similar to that of diamond. Key Silicon atom Oxygen atom Crystalline s
June 2021, AS Unit 1, Q10 (1 mark): Which substance has a giant lattice of atoms? A diamond B ice C poly(ethene) D sodium chloride
June 2021, AS Unit 1, Q11 (1 mark): Which compound has bonds that are the most polar? A H2O B H2S C NH3 D PH3
June 2021, AS Unit 1, Q22(c)(i) (1 mark): Draw a dot-and-cross diagram of a PCl4 Show only outer shell electrons. (1)
June 2021, AS Unit 2, Q22(a) (2 marks): Complete the dot-and-cross diagram to show the bonding in phosgene. (2) O C Cl Cl
January 2021, AS Unit 1, Q7 (1 mark): The Period 2 element with the highest melting temperature is A aluminium B boron C carbon D silicon
January 2021, AS Unit 1, Q11 (1 mark): Which of these does not have a structure formed by a giant lattice of carbon atoms? A C60 fullerene B diamond C graphene D graphite
January 2021, AS Unit 1, Q12 (1 mark): Which of these molecules is the most polar? A HF B OF2 C BF3 D CF4 Use this space for any rough working. Anything you write in this space will gain no credit.
January 2021, AS Unit 1, Q19(b)(ii) (2 marks): Draw a dot-and-cross diagram to show the bonding in a molecule of SbCl5 . Use dots (•) to represent the Sb electrons, and crosses (x) to represent the Cl electr
January 2021, AS Unit 1, Q19(c)(i) (1 mark): State what is meant by the term dative covalent bond. (1)
January 2021, AS Unit 1, Q19(c)(ii) (1 mark): Complete the diagram to show the dative covalent bonds in Sb2Cl10 . (1) Cl Cl Cl Cl Cl Sb Sb Cl Cl Cl Cl Cl
January 2021, AS Unit 1, Q19(d) (1 mark): Arsenic also forms a pentachloride with the formula AsCl5 . Give one possible reason why nitrogen is the only Group 5 element that does not form a pentachloride
January 2021, AS Unit 1, Q20(d)(i) (1 mark): Complete the diagram of bromine monochloride to show the dipole. (1) Br Cl
January 2021, AS Unit 2, Q20(b)(i) (3 marks): Explain the type of bonding that occurs between the nitrogen atom and the hydrogen ion, when the positive ion forms. (3)
October 2020, AS Unit 1, Q13 (1 mark): How many lone pairs of electrons are there in the outer shell of the sulfur atom in a molecule of H2S? A zero B one C two D four
October 2020, AS Unit 1, Q17 (1 mark): Which diagram best represents the electron density in a molecule of hydrogen chloride? A H Cl B H Cl C H Cl D H Cl
October 2020, AS Unit 1, Q19(c)(i) (2 marks): Draw a dot‑and‑cross diagram of the ammonium ion. Use dots (●) for the nitrogen electrons and crosses (×) for the hydrogen electrons. (2)
January 2020, AS Unit 1, Q11 (1 mark): Which of these forms of carbon does not contain delocalised electrons? A diamond B C60 fullerene C graphene D graphite
January 2020, AS Unit 1, Q16 (1 mark): What is the number of ı bonds and ʌ bonds in one molecule of this compound? ı bonds ʌ bonds A 15 3 B 39 3 C 15 6 D 39 6 Use this space for any rough working. An
January 2020, AS Unit 1, Q18(d) (1 mark): Chlorine occurs naturally as a diatomic molecule. Draw a dot-and-cross diagram to show the bonding in a molecule of chlorine. Show outer shell electrons only. (
January 2020, AS Unit 1, Q19(a)(ii) (3 marks): Explain, with reference to structure and bonding, why silicon has a very high melting temperature. (3)
June 2019, AS Unit 1, Q2 (1 mark): Which of these molecules is the most polar? A H H B H F C H Cl D H Br
June 2019, AS Unit 1, Q3 (1 mark): Covalent bonding is best described as the electrostatic attraction between A oppositely charged ions B positive ions and delocalised electrons C a shared pair o
June 2019, AS Unit 1, Q23(a) (1 mark): Draw an electron density map for a molecule of oxygen. (1)
June 2019, AS Unit 1, Q23(c)(i) (2 marks): Complete the dot-and-cross diagram for the POCl3 molecule. Use crosses ( ) for the phosphorus electrons, dots ( ) for the chlorine electrons and circles ( ) for
June 2019, AS Unit 1, Q23(e)(i) (4 marks): Explain two ways in which the physical properties of diamond and graphite differ. Refer to their structure and bonding in your answer. (4) diamond graphite
June 2019, AS Unit 1, Q23(e)(ii) (1 mark): State how the structure of graphene is related to the structure of graphite. (1)
June 2019, AS Unit 1, Q23(e)(iii) (2 marks): State a use for graphene, identifying the property that makes it suitable for that use. (2)
January 2019, AS Unit 1, Q22(b)(i) (1 mark): Draw a dot-and-cross diagram to show the bonding in a molecule of nitrogen. (1)
January 2019, AS Unit 1, Q24(d)(ii) (2 marks): Describe how two AlCl3 molecules are joined together in the dimer. Include a diagram in your answer. (2)

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