Ions and ionic bonds — Paper 3 · IGCSE Science - Combined 0653

8 (a) An atom of chlorine is represented by the symbol: 1735Cl (i) State the number of electrons, neutrons and protons in this atom. electrons … neutrons … protons … [2] (ii) Complete Table 8.1 to show the relative charges and approximate relative masses of electrons, neutrons and protons. Table 8.1 particle relative charges approximate relative masses electrons neutrons protons [2] (b) Chlorine is a non-metallic element. State the types of bond that form when chlorine reacts with sodium and with hydrogen. Explain your answers. sodium and chlorine … explanation … … hydrogen and chlorine … explanation … … [3] (c) Chlorine gas is bubbled through solutions of • sodium bromide, • zinc chloride, • magnesium iodide. Predict which solutions react with chlorine gas. … [1] (d) State the test and the positive result for chlorine gas. test … result … [2]

10 marks

Mark scheme: 8(a)(i) (electrons) 17 (neutrons) 18 (protons) 17 ;; all three correct (2) one or two correct (1) 2 8(a)(ii) (particle) (relative charges) (approximate relative masses) (electrons) –1 negligible / 1/2000 (neutrons) 0 / none 1 (protons) +1 1 ;; all three relative charges (1) all three approximate relative masses (1) 2 8(b) (sodium and chlorine) ionic and (hydrogen and chlorine) covalent ; (sodium explanation) metal and non-metal / loss gain of electrons ; (hydrogen explanation) two non-metals / shared electrons ; 3 Question Answer Marks 8(c) (sodium) bromide AND (magnesium) iodide ; 1 8(d) (test) (damp) litmus paper ; (result) bleaches / turns white ; 2

This question in 0653/32 Feb/March 2018

8 (a) The electrolysis of aqueous copper chloride is shown in Fig. 8.1. Copper forms on electrode P. low voltage d.c. supply electrode P gas copper Fig. 8.1 (i) Predict the type of bonding between the particles in solid copper chloride. … [1] (ii) Copper chloride is produced when one atom of copper reacts with two atoms of chlorine. Predict the formula of this compound. … [1] (iii) Name electrode P. … [1] (iv) Name the gas that forms at the other electrode. … [1] (b) Copper compounds are used as catalysts. (i) Describe what is meant by a catalyst. … … [1] (ii) State the name of the collection of metals in the Periodic Table that includes copper. … [1] (c) Copper is extracted from copper oxide by heating it with carbon. (i) Complete the word equation for this reaction. copper + + oxide [2] (ii) Explain why this reaction is described as a redox reaction. … … [1]

9 marks

Mark scheme: 8(a)(i) ionic ; 1 8(a)(ii) CuCl2 ; 1 8(a)(iii) cathode ; 1 8(a)(iv) chlorine ; 1 8(b)(i) speeds up a reaction (without being used up) ; 1 8(b)(ii) transition (metals) ; 1 8(c)(i) carbon on left-hand side and copper on the right-hand side ; carbon dioxide / monoxide on the right-hand side ; 2 8(c)(ii) oxygen is removed from the copper oxide / carbon reacts with oxygen / idea that oxidation and reduction occur at the same time / oxygen is transferred / loss and gain of oxygen ; 1 Q uestion Answer Mar rks

This question in 0653/31 May/June 2018

2 (a) The Periodic Table contains the symbols of all of the elements. Complete the sentences about the Periodic Table. The Periodic Table lists the elements in order of their … number. The unreactive gases in Group VIII, which include helium, neon and argon, are known as the … gases. The collection of metals in the middle of the Periodic Table have high densities and form coloured compounds. They are known as the … elements. [3] (b) Carbon dioxide is a compound of carbon and oxygen, two non-metallic elements. (i) State the name of the type of bonding between a carbon atom and an oxygen atom. … [1] (ii) Describe, in terms of electrons, the bonding between a carbon atom and an oxygen atom. … … [1] (c) The compound sodium chloride contains sodium ions and chloride ions. Describe, in terms of electrons, the formation of ions from atoms. … … [1] (d) A mixture contains aqueous sodium chloride and insoluble powdered charcoal (carbon). (i) Suggest how the powdered charcoal can be separated from the mixture. … … [1] (ii) Suggest how water can be removed from aqueous sodium chloride. … … [1] (iii) State whether the separation of this mixture into charcoal, water and sodium chloride is a physical change or a chemical change. Explain your answer. change … explanation … … [1]

9 marks

Mark scheme: 2(a) atomic / proton ; noble ; transition ; 3 2(b)(i) covalent ; 1 2(b)(ii) (electrons are) shared ; 1 2(c) (electrons are) lost / gained / lost and gained ; 1 Question Answer Marks 2(d)(i) filter / filtering / filtration ; 1 2(d)(ii) evaporation ; 1 2(d)(iii) physical and no new substance(s) is / are made ; 1

This question in 0653/33 Oct/Nov 2018

2 (a) Sodium chloride is an ionic compound. It dissolves in water. Water is a covalent compound. (i) State the formula of sodium chloride. … [1] (ii) Describe the formation of ionic bonds and of covalent bonds. Use ideas about electrons in your answer. ionic bonds … … … covalent bonds … … … [2] (iii) Use the words solvent, solute and solution to describe sodium chloride, water and aqueous sodium chloride. Sodium chloride is a … . Water is a … . Aqueous sodium chloride is a … . [2] (b) A student uses the apparatus shown in Fig. 2.1 for the electrolysis of concentrated aqueous sodium chloride. low voltage d.c. supply – + inert electrodes concentrated aqueous sodium chloride Fig. 2.1 (i) State whether this electrolysis is a physical change or a chemical change. Explain your answer. change … explanation … … [1] (ii) Name the non-metallic element used to make the inert electrodes. … [1] (iii) Name the positive and the negative electrodes. positive … negative … [1] (iv) During this electrolysis two gases are produced. Identify the gases produced at the positive and at the negative electrodes. positive … negative … [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) 1 2(a)(ii) (ionic) electrons lost and gained ; (covalent) electrons shared ; 2 2(a)(iii) (sodium chloride) solute (water) solvent (aq NaCl) solution ;; all three correct (2) one or two correct (1) 2 2(b)(i) (change) chemical and (explanation) new substance(s) made ; 1 2(b)(ii) carbon / C ; 1 Question Answer Marks 2(b)(iii) (positive) anode and (negative) cathode ; 1 2(b)(iv) (positive) chlorine / Cl2 ; (negative) hydrogen / H2 ; 2

This question in 0653/32 May/June 2019

5 (a) The electrolysis of concentrated aqueous sodium chloride is shown in Fig. 5.1. low voltage d.c. supply … … – + … Fig. 5.1 (i) Complete Fig. 5.1 by adding the labels anode, cathode and electrolyte. [2] (ii) One of the products of this electrolysis is chlorine gas. Identify the two other products. 1. … 2. … [2] (iii) Describe a chemical test for chlorine gas and state the positive result. test … … result … [2] (b) An atom of sodium has atomic number 11 and nucleon number 23. State the number of protons and the number of neutrons in this atom of sodium. protons … neutrons … [2] (c) A chlorine atom has 17 electrons. A chloride ion has the symbol Cl –. Complete Fig. 5.2 to show the electron arrangements in a chlorine atom and in a chloride ion. × × × × chlorine atom chloride ion Fig. 5.2 [2] [Total: 10]

10 marks

Mark scheme: 5(a)(i) all three correct = 2 marks one or two correct = 1 mark 2 5(a)(ii) sodium hydroxide / NaOH ; hydrogen / H2 ; 2 5(a)(iii) (test) damp litmus paper ; (result) (blue / red to) white ; 2 5(b) (protons) 11 ; (neutrons) 12 ; 2 5(c) (chlorine atom) 2, 8, 7 drawn ; (chloride ion) 2, 8, 8 drawn ; 2

This question in 0653/32 Oct/Nov 2019

5 (a) The electrolysis of concentrated aqueous sodium chloride is shown in Fig. 5.1. low voltage d.c. supply … … – + … Fig. 5.1 (i) Complete Fig. 5.1 by adding the labels anode, cathode and electrolyte. [2] (ii) One of the products of this electrolysis is chlorine gas. Identify the two other products. 1. … 2. … [2] (iii) Describe a chemical test for chlorine gas and state the positive result. test … … result … [2] (b) An atom of sodium has atomic number 11 and nucleon number 23. State the number of protons and the number of neutrons in this atom of sodium. protons … neutrons … [2] (c) A chlorine atom has 17 electrons. A chloride ion has the symbol Cl –. Complete Fig. 5.2 to show the electron arrangements in a chlorine atom and in a chloride ion. × × × × chlorine atom chloride ion Fig. 5.2 [2] [Total: 10]

10 marks

Mark scheme: 5(a)(i) all three correct = 2 marks one or two correct = 1 mark 2 5(a)(ii) sodium hydroxide / NaOH ; hydrogen / H2 ; 2 5(a)(iii) (test) damp litmus paper ; (result) (blue / red to) white ; 2 5(b) (protons) 11 ; (neutrons) 12 ; 2 5(c) (chlorine atom) 2, 8, 7 drawn ; (chloride ion) 2, 8, 8 drawn ; 2

This question in 0653/33 Oct/Nov 2019

8 Sodium chloride, NaCl, is an ionic compound. (a) Name one method of obtaining solid sodium chloride from aqueous sodium chloride. … [1] (b) The electronic structures of an atom of sodium, Na, and of an atom of chlorine, Cl, are shown in Fig. 8.1. Na Cl atom atom Fig. 8.1 Complete Fig. 8.2 to show the electronic structure of a sodium ion, Na+, and of a chloride ion, Cl –. Na+ Cl – ion ion Fig. 8.2 [2] (c) Concentrated aqueous sodium chloride is electrolysed using inert electrodes, as shown in Fig. 8.3. low voltage d.c. supply – + concentrated aqueous sodium chloride Fig. 8.3 Complete the word equation for the electrolysis of concentrated aqueous sodium chloride. concentrated aqueous sodium + + sodium hydroxide chloride [2] (d) Suggest the pH of aqueous sodium hydroxide and its effect on the colour of Universal Indicator. pH … colour … [2] (e) State the effect of chlorine gas on damp litmus paper. … [1] [Total: 8]

8 marks

Mark scheme: 8(a) evaporate ; allow distil / crystallise / boil 1 8(b) drawn: Na+ 2, 8 ; Cl– 2, 8, 8 ; 2 8(c) (either order) concentrated aqueous sodium chloride  sodium hydroxide + hydrogen ; + chlorine ; 2 8(d) pH > 7 to 14 ; colour blue-green / blue / purple ; 2 8(e) (blue / purple to) white / bleached ; 1

This question in 0653/32 Feb/March 2020

2 (a) A teacher uses the apparatus shown in Fig. 2.1. magnesium delivery tube gas test-tube heat water water heat Fig. 2.1 The teacher heats the water to make steam. The steam passes over heated magnesium. The magnesium burns brightly. A white solid and a gas form. The gas is collected in a test-tube. The teacher tests the gas using a lighted splint. It burns with a squeaky pop. (i) Identify one chemical change and one physical change in the teacher’s experiment. chemical change … physical change … [2] (ii) Give the chemical names for the white solid and the gas that form. white solid … gas … [2] (b) An atom of sodium can be represented by the symbol shown. 2 1 13Na Deduce the number of protons and the number of neutrons in this atom. protons … neutrons … [2] (c) The electronic structure of a sodium atom is shown in Fig. 2.2. Fig. 2.2 Sodium reacts with chlorine to make sodium chloride. Sodium chloride contains sodium ions, Na+, and chloride ions, Cl –. (i) State the change to the electronic structure of sodium atoms when sodium reacts with chlorine. … [1] (ii) State which feature of the electronic structure of the sodium ion, Na+, makes the ion stable. … … [1] [Total: 8]

8 marks

Mark scheme: 2(a)(i) (chemical change) burning / combustion / gas test ; (physical change) boiling / water to steam ; 2 2(a)(ii) (white solid) magnesium oxide ; (gas) hydrogen ; 2 2(b) (protons) 11 ; (neutrons) 12 ; 2 2(c)(i) loses one electron / loses outer electron ; 1 2(c)(ii) full outer shell / same as noble gas (electronic structure) ; 1

This question in 0653/31 May/June 2020

2 (a) A teacher puts a small piece of sodium onto water in a water trough, as shown in Fig. 2.1. sodium water water trough Fig. 2.1 The students observe the reaction between sodium and water. The teacher repeats the experiment using potassium instead of sodium. (i) Describe one similarity in the reactions of potassium and of sodium with water. … [1] (ii) Describe one difference between the observations for the reactions of potassium and of sodium with water. Explain the reason for this difference. difference … explanation … [2] (b) Iron is in a collection of metals in the Periodic Table shown on page 20. (i) Name this collection of metals. … [1] (ii) State one physical property of iron that is also a physical property of sodium. … [1] (iii) State one property of iron that is not a property of sodium. … [1] (c) The metals aluminium, copper and iron can be recycled. State one reason, other than cost, why these metals can be recycled. … … [1] (d) An atom of aluminium is represented by the symbol shown. 2 1 37Al (i) Complete Fig. 2.2 to show the electronic structure of this atom. Fig. 2.2 [2] (ii) Describe how this atom forms an aluminium ion, Al 3+. … … [1] [Total: 10]

10 marks

Mark scheme: 2(a)(i) any one from: exothermic / releases heat ; fizzes / releases gas / H2 ; forms an alkaline solution ; max 1 2(a)(ii) (difference) (potassium) burns / produces flames ; (explanation) (potassium is) more reactive (than sodium) ; 2 2(b)(i) transition (elements) ; 1 2(b)(ii) any one from: (good) conductor of electricity ; (good) conductor of heat ; malleable ; 1 Question Answer Marks 2(b)(iii) any one from: high melting point ; high boiling point ; high density ; forms coloured compounds ; (acts as) catalyst (as element or in compounds) ; 1 2(c) (they are) finite resources / (they’re) running out / will run out / more energy used for extraction / less energy to recycle (than extract) / no need to mine / does not go into landfill ; 1 2(d)(i) 2, 8, 3 shown correctly ;; (if incorrect allow 1 mark for 13 electrons drawn) 2 2(d)(ii) loss of electrons ; 1

This question in 0653/32 May/June 2020

5 (a) Lithium, sodium and potassium are three elements in Group I of the Periodic Table, as shown in Fig. 5.1. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 Fig. 5.1 Identify which of these three elements has: the lowest density … the highest reactivity … the highest melting point. … [2] (b) Chlorine, bromine and iodine are three elements in Group VII of the Periodic Table. They exist as diatomic molecules. (i) Describe what is meant by diatomic. … … [1] (ii) Complete the dot‑and‑cross diagram in Fig. 5.2 to show all the outer shell electrons in a molecule of chlorine, Cl 2. Cl Cl Fig. 5.2 [2] (iii) State the type of chemical bonding in a molecule of chlorine. … [1] (c) When sodium and chlorine react together, they form sodium chloride, NaCl. (i) Describe what happens to sodium atoms and to chlorine atoms when they react together. Use ideas about electrons in your answer. sodium atoms … … chlorine atoms … … [2] (ii) Complete Table 5.1 by stating whether each substance conducts or does not conduct electricity when solid, molten (liquid) or gas. Use a tick (✓) for conducts or a cross (✗) for does not conduct in each empty box. Table 5.1 solid molten (liquid) gas sodium sodium chloride chlorine [3] [Total: 11]

11 marks

Mark scheme: 5(a) (lowest density) lithium / Li (highest reactivity) potassium / K (highest melting point) lithium / Li Three correct scores (2) ;; Two or one correct scores (1) ; 2 5(b)(i) contains only two atoms (per molecule) ; 1 5(b)(ii) correct diagram showing two shared electrons ; and 6 non-shared (3 pairs of) electrons on each chlorine ; 2 5(b)(iii) covalent ; 1 5(c)(i) (sodium atoms) lose electrons / lose one electron each ; (chlorine atoms) gain electrons / gain one electron each ; 2 5(c)(ii) ;;; (1) for each correct row 3

This question in 0653/33 May/June 2022

2 (a) Potassium, K, and fluorine, F, are both elements. The electronic structure of a potassium atom and of a fluorine atom are shown in Fig. 2.1. K F potassium fluorine atom atom Fig. 2.1 Potassium and fluorine react exothermically to form the compound potassium fluoride. (i) Complete Fig. 2.2 to show the electronic structure of a potassium ion and of a fluoride ion in potassium fluoride. K F potassium fluoride ion ion Fig. 2.2 [2] (ii) State what is meant by the term exothermic. … … [1] (iii) State what is meant by the terms element and compound. element … … compound … … [2] (b) A student investigates the rate of reaction between solid potassium oxide and dilute sulfuric acid. (i) State the name of the salt that forms in this reaction. … [1] (ii) Suggest two ways of increasing the rate of this reaction. 1 … 2 … [2] (c) Potassium carbonate reacts with dilute hydrochloric acid to make potassium chloride and a gas and one other product. Complete the word equation for this reaction. dilute potassium potassium + hydrochloric + + carbonate chloride acid [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) potassium any symbols showing 2,8,8 ; 2 fluoride any symbols showing 2,8 ; 2(a)(ii) (a reaction in which) thermal / heat, energy is released ; 1 2(a)(iii) element (contains) one type of atom (only) ; 2 compound two or more elements chemically, combined / bonded / joined together ; 2(b)(i) potassium sulfate ; 1 2(b)(ii) any two from: 2 increase temperature ; decrease particle size (of solid / potassium oxide) ; increase concentration (of acid) ; add a catalyst ; 2(c) 2 carbon dioxide ; water ;

This question in 0653/31 Oct/Nov 2022

5 Magnesium sulfate is produced by reacting excess magnesium oxide with dilute sulfuric acid. (a) Complete the word equation for this reaction. magnesium + + sulfate [2] (b) A coloured aqueous solution is used to measure the pH of dilute sulfuric acid. (i) State the name of the coloured aqueous solution that is used to measure the pH of acids and alkalis. … [1] (ii) Suggest the pH value of dilute sulfuric acid. … [1] (c) Complete the sentences about the preparation of salt crystals. Use words from the list. Each word may be used once, more than once or not at all. acid filtering heating magnesium distillation magnesium sulfate shaking solid Excess magnesium oxide is added to dilute sulfuric acid and stirred until no more … dissolves. Pure aqueous magnesium sulfate is separated by … . Some water is removed by gentle … . The solution is then left to form pure dry crystals of the salt called … . [4] (d) Magnesium sulfate contains magnesium ions, Mg2+. Describe how magnesium ions are formed from magnesium atoms. … [1] (e) Aqueous magnesium sulfate is broken down by an electric current. State the name of this process. … [1] [Total: 10]

10 marks

Mark scheme: 5(a) magnesium oxide + sulfuric acid  magnesium sulfate + water ;; LHS (1) RHS (1) 5(b)(i) universal indicator ; 1 5(b)(ii) 1 – 6 ; 1 5(c) solid ; filtering / filtration ; heating ; magnesium sulfate ; 4 5(d) loss of electrons ; 1 Question Answer Marks 5(e) electrolysis ; 1

This question in 0653/33 May/June 2023

2 Lithium is an element in Group I of the Periodic Table. (a) An atom of lithium is represented as shown. 73Li Complete Table 2.1 to show the number of protons, electrons and neutrons in one atom of 73Li. Table 2.1 number of protons number of electrons number of neutrons [2] (b) Describe what happens when an atom of lithium becomes an ion of lithium. … … [1] (c) Lithium reacts slowly with oxygen at room temperature to form lithium oxide. This reaction is exothermic. (i) Balance the symbol equation for this reaction. [1] ……. Li + .…... O2 ……. Li2O (ii) Circle the word that describes the reaction between lithium and oxygen. decomposition distillation neutralisation oxidation [1] (iii) Describe one observation that shows the reaction is exothermic. … … [1] (d) There is an alloy that contains lithium and aluminium only. Tick (3) one box to show which statement describes this alloy. It contains one type of atom only. It is a mixture. It has the chemical properties of aluminium only. It has the physical properties of lithium only. [1] (e) Aluminium is used to make cooking pans. Suggest why lithium is not used to make cooking pans. … … [1] (f) Recycling aluminium is cheaper than producing it from its ore. Suggest one other reason why aluminium is recycled. … … [1] [Total: 9]

9 marks

Mark scheme: 2(a) 2 number of protons number of electrons number of neutrons 3 3 4 ;; 3 correct = [2] 1–2 correct = [1] 2(b) loss of one electron (from its outer shell) ; 1 2(c)(i) 4Li + O2 → 2Li2O ; 1 2(c)(ii) oxidation circled ; 1 2(c)(iii) idea that heat is transferred from reactants / temperature (of reaction mixture) increases ; 1 2(d) second box ticked (It is a mixture.) ; 1 2(e) too reactive / melting point too low / too soft ; 1 2(f) (aluminium is a) finite resource / will run out / non-renewable ; 1

This question in 0653/32 Feb/March 2024

2 The elements chlorine, bromine and iodine are diatomic covalent molecules. (a) State the meaning of diatomic. … [1] (b) Complete the dot-and-cross diagram in Fig. 2.1 to show the outer-shell electrons in a molecule of chlorine, Cl2. Cl Cl Fig. 2.1 [2] (c) Chlorine reacts exothermically with sodium to form the ionic compound sodium chloride. (i) State the meaning of exothermic. … … [1] (ii) Describe what happens to a sodium atom and to a chlorine atom when they react to form the ionic compound sodium chloride. Use ideas about electrons in your answer. sodium atom … … chlorine atom … … [2] (iii) Describe the difference in volatility between ionic compounds and covalent compounds. … … [1] (d) Solid sodium carbonate reacts with dilute hydrochloric acid to form aqueous sodium chloride, carbon dioxide and one other product. (i) Identify the solute and the solvent in aqueous sodium chloride. solute … solvent … [2] (ii) Complete the word equation for this reaction. sodium hydrochloric + + +carbonate acid [1] (iii) The structure of sodium carbonate is shown in Fig. 2.2. O C Na+ O– O– Na+ Fig. 2.2 Deduce the formula of sodium carbonate. … [1] [Total: 11]

11 marks

Mark scheme: 2(a) (molecule containing) two atoms (chemically combined) ; 1 Question Answer Marks 2(b) one shared pair of electrons ; three lone pairs / six non-bonding electrons on each atom and all else correct ; 2 2(c)(i) (reaction that) gives out thermal energy ; 1 2(c)(ii) (sodium atom) loses one electron ; (chlorine atom) gains one electron ; 2 2(c)(iii) covalent are more (volatile) ; 1 2(d)(i) (solute) sodium chloride / NaCl ; (solvent) water / H2O ; 2 2(d)(ii) ; 1 2(d)(iii) Na2CO3 ; 1

This question in 0653/31 May/June 2024

5 Aluminium ore contains aluminium oxide. Aluminium is extracted from aluminium oxide in the process shown in Fig. 5.1. carbon cathode carbon anode – + molten mixture containing aluminium oxide molten aluminium Fig. 5.1 (a) (i) Circle the name of the process shown in Fig. 5.1. chromatography crystallisation electrolysis filtration [1] (ii) State the name of the ore that contains aluminium oxide. … [1] (b) Explain why the extraction of aluminium from aluminium oxide is a reduction reaction. … … [1] (c) An atom of aluminium is represented as shown. 27 13Al (i) Describe what is meant by nucleon number. … … [1] (ii) Deduce the number of neutrons in this atom. … [1] (d) The electronic structure of an aluminium atom is shown in Fig. 5.2. Al Fig. 5.2 When aluminium reacts, aluminium atoms form aluminium ions. Complete Fig. 5.3 to show the electronic structure of an aluminium ion. Al Fig. 5.3 [1] (e) Aluminium oxide, Al2O3 , is an ionic compound. Ammonia, NH3 , is a covalent compound. Complete Table 5.1 to show the electrical conductivity of aluminium, aluminium oxide and ammonia as solids and as liquids. Use a tick (✓) to show an electrical conductor. Use a cross (✗) to show an electrical non‑conductor. Two have been done for you. Table 5.1 Key aluminium aluminium oxide ammonia ✓ = electrical solid ✓ ✗ conductor ✗ = electrical liquid non‑conductor [2] [Total: 8]

8 marks

Mark scheme: 5(a)(i) electrolysis (circled) ; 1 5(a)(ii) bauxite ; 1 5(b) oxygen is lost ; 1 5(c)(i) the (total) number of protons and neutrons ; 1 5(c)(ii) 14 ; 1 5(d) 2 electrons in inner shell, 8 in second shell and none in third shell ; 1 5(e) ;; four correct = (2) two or three correct = (1) 2

This question in 0653/32 May/June 2024

5 Part of the Periodic Table is shown in Fig. 5.1. Group I II III IV V VI VII VIII H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Fig. 5.1 (a) (i) Draw one straight line to show the trend in metallic character across a period. decreases across a period from left to right metallic increases across a period character from left to right stays the same across a period from left to right [1] (ii) State the name of the collection of metals that includes iron, Fe, and copper, Cu. … [1] (b) Lithium, Li, sodium, Na, and potassium, K, are in Group I of the Periodic Table. State the trend in the melting point and the trend in the reaction with water of these elements going down Group I. melting point … … reaction with water … … [2] (c) Sodium, Na, reacts with fluorine, F, to form sodium fluoride. Fig. 5.2 shows the electronic structure of a sodium atom and of a fluorine atom. sodium atom fluorine atom Fig. 5.2 When sodium atoms react with fluorine atoms, sodium ions and fluoride ions form. Complete the dot-and-cross diagrams in Fig. 5.3 to show all of the electrons in a sodium ion and in a fluoride ion. sodium ion fluoride ion Fig. 5.3 [2] (d) The electronic structure of an atom of element Z is shown in Fig. 5.4. element Z Fig. 5.4 (i) Use the Periodic Table to identify element Z. … [1] (ii) Sodium and element Z do not easily form a compound together. Use the electronic structure shown in Fig. 5.4 to explain this observation. … … … [2] [Total: 9]

9 marks

Mark scheme: 5(a)(i) metallic character - decreases across a period from left to right ; 1 5(a)(ii) transition (elements) ; 1 5(b) (melting point) decreases (down Group I) ; (reaction with water) more reactive / reacts more vigorously / reacts faster (down Group I) ; 2 5(c) (sodium ion) 2 electrons in 1st shell, 8 in 2nd shell only (no electrons in 3rd shell) ; (fluoride ion) 2 electrons in 1st shell, 8 in 2nd shell only ; 2 5(d)(i) argon ; 1 5(d)(ii) Z has full outer shell / 8 electrons in outer shell ; Z does not need to gain an electron (from sodium) / Z has a stable electron arrangement ; 2

This question in 0653/33 May/June 2024

6 Table 6.1 shows the products and observations at the electrodes in the electrolysis of three electrolytes. Table 6.1 negative electrode positive electrode electrolyte product observation product observation molten bubbles of lead grey liquid lead(II) bromide … red-brown gas concentrated bubbles of bubbles of aqueous hydrogen chlorine colourless gas green gas sodium chloride bubbles of bubbles of dilute sulfuric acid … colourless gas … colourless gas (a) Complete Table 6.1. [3] (b) Explain why the mass of concentrated aqueous sodium chloride decreases during electrolysis. … … [1] (c) Use Table 6.1 to explain why electrolysis is a chemical change. … … [1] (d) Inert electrodes are used in each electrolysis. Name one substance used as inert electrodes. … [1] (e) State the name of the negative electrode. … [1] (f) Electrolysis is an endothermic process. State the meaning of endothermic. … … [1] (g) Draw one straight line from each description to the correct substance. description substance chlorine salt that contains ionic bonds dilute sulfuric acid compound with a pH less than 7 hydrogen lead Group VII element lead(II) bromide [3] [Total: 11]

11 marks

Mark scheme: 6(a) bromine ; 3 hydrogen ; oxygen ; 6(b) products are gases (which are released) ; 1 6(c) new substances are formed / change cannot be directly reversed / cannot easily be reversed ; 1 6(d) platinum / carbon / graphite ; 1 6(e) cathode ; 1 6(f) a process that takes in (thermal) energy (from the surroundings) / a change where the temperature of the surroundings 1 decreases ; 6(g) 3 description substance chlorine salt that contains ionic dilute sulfuric bonds acid compound with a pH less hydrogen than 7 Group VII element lead lead(II) bromide ; ; ; each correct line = 1 mark

This question in 0653/32 Feb/March 2025

4 Lithium fluoride, LiF, is an ionic compound. (a) Complete the sentences to explain why lithium fluoride has a high melting point. Choose words from the list. Each word may be used once, more than once or not at all. configuration attraction conduction gases molecules weak strong solids An ionic bond is a … electrostatic … between ions with opposite charges. Ionic compounds are … at room temperature and pressure. [3] (b) Lithium fluoride contains lithium ions, Li+, and fluoride ions, F–. Fig. 4.1 shows the dot-and-cross diagram for lithium fluoride. – + Li F Fig. 4.1 Use Fig. 4.1 to describe what happens when a lithium atom and a fluorine atom form ions. lithium … … fluorine … … [2] (c) The Periodic Table gives information about an atom of fluorine, as shown in Fig. 4.2. 9 F fluorine 19 Fig. 4.2 Deduce the number of protons and neutrons in this atom of fluorine. number of protons … number of neutrons … [2] (d) Fluorine is in Group VII of the Periodic Table. Complete the sentences about elements in Group VII. Choose phrases from the list. Each phrase may be used once, more than once or not at all. more than less than the same as The reactivity of bromine is ……………………………….. the reactivity of fluorine. The density of iodine is ……………………………….. the density of fluorine. The number of electrons in the outer shell of fluorine is ……………………………….. the number of electrons in the outer shell of chlorine. [2] [Total: 9]

9 marks

Mark scheme: 4(a) strong ; 3 attraction ; solids ; 4(b) lithium atom loses one electron ; 2 fluorine atom gains one electron ; 4(c) 9 protons ; 2 10 neutrons ; 4(d) less than 2 more than the same as ;; all three correct = 2 marks one or two correct = 1 mark

This question in 0653/33 May/June 2025