Atomic structure and the Periodic Table — Paper 3 · IGCSE Sciences - Co-ordinated (Double) 0654

9 Magnesium is an element in Group II of the Periodic Table. (a) (i) An atom of magnesium has an atomic number of 12 and a mass number of 26. State the numbers of protons, neutrons and electrons in this magnesium atom. number of protons … number of neutrons … number of electrons … [3] (ii) State the total number of elements that are in the same period of the Periodic Table as magnesium. … [1] (b) Fig. 9.1 shows apparatus that a student uses to investigate the temperature change when excess magnesium reacts with dilute hydrochloric acid. thermometer lid insulated dilute hydrochloric container acid magnesium Fig. 9.1 Table. 9.1 shows temperature measurements the student records during the investigation. Table 9.1 temperature of the acid before the reaction / °C 20 temperature of the mixture when reaction has finished / °C 45 (i) Name the gas that is produced when magnesium reacts with dilute hydrochloric acid. … [1] (ii) Suggest the change in the pH of the mixture inside the insulated container during the reaction. Explain your answer. change … explanation … … [2] (iii) The student concludes that the reaction between magnesium and dilute hydrochloric acid is endothermic. State and explain whether or not the student has made a correct conclusion. … … … [2] (c) Fig. 9.2 shows the apparatus the student uses to investigate the rate of reaction between magnesium and dilute hydrochloric acid. measuring cylinder bung gas test-tube dilute hydrochloric acid magnesium water Fig. 9.2 State two changes to the reaction conditions the student could make which increase the speed that gas fills the measuring cylinder. 1 … 2 … [2]

11 marks

Mark scheme: 9(a)(i) 12 ; 14 ; 12 ; 3 9(a)(ii) 8 ; 1 9(b)(i) hydrogen ; 1 9(b)(ii) increases ; mixture becoming less acidic / the acid is being used up / is becoming less ; 2 9(b)(iii) (incorrect) reaction is exothermic ; because temperature increased / endo thermic would show temperature decrease ; reference to transfer of chemical to thermal energy / or vv if endothermic ; max 2 9(c) increase acid concentration ; increase temperature ; increase surface area of magnesium ; max 2

This question in 0654/31 May/June 2017

2 Fig. 2.1 shows diagrams of atoms of two elements, J and Q. electron Z electron shell x x x x x x x x x x x x x x x x x x x J Q Fig. 2.1 (a) (i) Name the central part of atom J labelled Z. … [1] (ii) Name the two sub-atomic particles in Z. 1 … 2 … [2] (iii) State which number places elements in order in the Periodic Table. … [1] (iv) Use the Periodic Table on page 28 to determine the identity of element Q. element Q is … [1] (b) The elements hydrogen and oxygen are combined in the compounds hydrogen peroxide and water. Fig. 2.2 shows diagrams of molecules of these compounds. H O O O H H H hydrogen peroxide water Fig. 2.2 (i) State the chemical formula of hydrogen peroxide. … [1] (ii) Describe a chemical test for water and the positive result of this test. description of test … … result … [2] (c) Water supplied to homes is treated with chlorine. Explain why this is done. … … … [2]

10 marks

Mark scheme: 2(a)(i) nucleus ; 1 2(a)(ii) proton ; neutron ; 2 2(a)(iii) atomic number / proton number / number of protons in one atom ; 1 2(a)(iv) N / nitrogen ; 1 2(b)(i) H2O2 ; 1 2(b)(ii) (anhydrous) cobalt chloride (paper) ; (blue to) pink ; or (anhydrous) copper(II) sulfate ; (white to) blue ; 2 2(c) kills harmful microorganisms / sterilises the water ; make it safe to drink / avoid (waterborne) diseases / owtte ; 2

This question in 0654/32 May/June 2017

12 Electrolysis occurs when an electric current passes through a solution that contains ions. (a) (i) State the general name given to solutions that contain ions. … [1] (ii) State the name of the negative electrode. … [1] (b) Fig. 12.1 shows the electrolysis of copper chloride solution. copper chloride solution carbon electrode L carbon electrode M d.c. power supply – + Fig. 12.1 (i) Electrode L changes colour. Explain this observation. … … [1] (ii) A gas is given off at electrode M. Name the gas and describe a safe chemical test for it. name of gas … test … positive result of test … [3] (c) Bromine is a non-metal in Group VII of the Periodic Table. (i) State and explain the type of electrical charge on a bromide ion. type of charge … explanation … … [2] (ii) Suggest why a bromine atom and a bromide ion have almost the same mass. Use ideas about the masses of protons, neutrons and electrons in your answer. … … … [2]

10 marks

Mark scheme: 12(a)(i) electrolyte ; 1 12(a)(ii) cathode ; 1 12(b)(i) reference to formation of copper / a copper layer ; 1 12(b)(ii) chlorine ; (damp) litmus / (Universal) indicator paper ; bleached ; 3 12(c)(i) negative ; non-metals form anions / bromine atoms gain (an) electron ; 2 12(c)(ii) the idea that there is only an electron difference ; electrons have no/negligible mass ; 2

This question in 0654/32 May/June 2017

2 The Periodic Table shows the elements arranged in order of atomic number. (a) (i) Define the term atomic number. … … [2] (ii) Explain why water does not have a place in the Periodic Table. … … [1] (iii) Table 2.1 contains some information about the structure of one atom of argon. Complete Table 2.1. Table 2.1 atomic mass number of number of element number number neutrons electrons argon 18 40 … … [2] (iv) Large amounts of argon are produced every day industrially. State the source of argon. … [1] (v) In the steel industry, argon is bubbled through molten steel at about 1500 °C to keep the steel mixed. Suggest why argon is a suitable gas for this process. … [1] (b) The maximum mass of potassium nitrate that dissolves in 100 cm3 of water is called the solubility of potassium nitrate. Fig. 2.1 shows the solubility of potassium nitrate at different temperatures. 100 90 80 70 solubility of potassium nitrate / g per 60 100 cm3 of water 50 40 30 20 10 0 0 10 20 30 40 50 60 temperature / °C Fig. 2.1 (i) Describe the trend shown in Fig. 2.1. … … [1] (ii) Two students make predictions, A and B, about what happens when 60 g of potassium nitrate is stirred into 100 cm3 of water at a temperature of 30 °C. Fig. 2.2 shows their predictions. prediction A prediction B all solid some solid dissolves remains undissolved Fig. 2.2 Use the information in Fig. 2.1 to explain why prediction B is correct. … … … [2]

10 marks

Mark scheme: 2(a)(i) number of protons ; in one atom (of an element) ; 2 2(a)(ii) water is not an element / is a compound / only elements in Periodic Table ; 1 2(a)(iii) 22 ; 18 ; 2 2(a)(iv) air ; 1 2(a)(v) argon does not react with the steel / argon is unreactive ; 1 2(b)(i) the higher the temperature the higher the solubility ; 1 2(b)(ii) at 30 °C maximum mass that dissolves is (about) 47 g / less than 60 g ; so not all the solid can dissolve / some solid settles out / owtte ; 2

This question in 0654/33 May/June 2017

2 The Periodic Table shows the chemical elements arranged in order of atomic number. (a) Fig. 2.1 is a diagram of an atom of element X. … – – + + + … – … Fig. 2.1 (i) On Fig. 2.1, label the three types of particle that make up this atom. [3] (ii) State the atomic (proton) number of element X. … [1] (iii) Use the Periodic Table on page 28 to identify element X. … [1] (iv) State the element in Group VII which is in the same period of the Periodic Table as element X. … [1] (b) Fig. 2.2 shows uses and properties of three elements. Draw straight lines to match each element with its use and property. One has been done as an example. element use property sterilising less dense aluminium water than air making food kills chlorine containers microorganisms filling weather resists helium balloons corrosion Fig. 2.2 [2]

8 marks

Mark scheme: 2(a)(i) protons correctly labelled ; neutrons correctly labelled ; electrons correctly labelled ; 3 2(a)(ii) 3 ; 1 2(a)(iii) lithium / Li ; 1 2(a)(iv) fluorine / F ; 1 Q Question 2(b) elem uses ments and uses c s and properties correctly connec correctly conne cted ; ected ; Answer Mar ks 2

This question in 0654/31 Oct/Nov 2017

2 (a) Complete the sentences about atomic structure using words chosen from the list. Each word may be used once, more than once or not at all. negative neutral neutrons nucleus positive protons In the middle of an atom is a … that contains … and … . Atoms also contain electrons that have a … electric charge. When electrons are removed from an atom, an ion with a … charge is formed. [3] (b) The Periodic Table includes the four metals listed. copper, Cu lithium, Li potassium, K sodium, Na (i) Using the Periodic Table on page 32, state which of these metals are in the same group of the Periodic Table, … and … and … are in the same period of the Periodic Table. … and … [2] (ii) Place the four metals in decreasing order of reactivity. … (most reactive) … … … (least reactive) [1] (iii) Fig. 2.1 shows lithium reacting with water. bubbles of lithium hydrogen gas water Fig. 2.1 Describe the test for hydrogen gas. test … result … [2] (c) Argon and chlorine are gaseous non-metallic elements. Predict and explain the change in appearance, if any, when these gases are bubbled through colourless sodium bromide solution, as shown in Fig. 2.2. argon chlorine sodium bromide sodium bromide solution solution Fig. 2.2 argon change … explanation … … chlorine change … explanation … … [3]

11 marks

Mark scheme: 2(a) nucleus then protons and neutrons ; negative ; positive ; 3 2(b)(i) lithium, sodium, potassium ; copper, potassium ; 2 2(b)(ii) potassium sodium lithium copper ; 1 2(b)(iii) burning / lighted splint ; pops ; 2 Question Answer Marks 2(c) no change / no reaction AND argon is unreactive / is an inert gas ; solution becomes orange ; bromine is released / chlorine displaces bromine / chlorine more reactive than bromine ; 3

This question in 0654/32 Oct/Nov 2017

2 (a) Complete Table 2.1 by choosing numbers from the list. Each number may be used once, more than once or not at all. 0 1 2 3 10 13 19 26 39 64 Use the information in the Periodic Table on page 28. Table 2.1 the atomic number of iron, Fe … the group number of aluminium, Al … the number of electrons in one atom of potassium, K … the number of neutrons in one atom of hydrogen, H … the number of protons in one atom of neon, Ne … [5] (b) The relative mass of a proton is 1 atomic mass unit. State the relative mass of a neutron and of an electron. relative mass of neutron … relative mass of electron … [2] (c) One type of steel is a mixture containing iron and cobalt. This steel is used to make tools. (i) Name the collection of metals in the Periodic Table that contains iron and cobalt. … [1] (ii) State the term used for a mixture containing metals. … [1] (iii) Suggest one reason why steel, rather than iron, is used to make tools. … … [1]

10 marks

Mark scheme: 2(a) 26 ; 3 ; 19 ; 0 ; 10 ; 5 Question Answer Marks 2(b) 1 ; zero / negligible / 1 / 2000 ; 2 2(c)(i) transition ; 1 2(c)(ii) alloy ; 1 2(c)(iii) harder / less malleable / takes a sharper edge / stronger ; 1

This question in 0654/33 Oct/Nov 2017

5 Group VII of the Periodic Table contains reactive non‑metallic elements called the halogens. A copy of the Periodic Table is shown on page 28. (a) Describe the trend in physical state of the elements chlorine, bromine and iodine at room temperature. … … [1] (b) (i) The mass number of a chlorine atom is 35. State the number of protons and of neutrons in this chlorine atom. protons … neutrons … [1] (ii) Name the part of an atom that contains the protons and neutrons. … [1] (c) Sodium chloride, NaCl, and chlorine oxide, Cl 2O, are compounds of chlorine. (i) State the type of chemical bonding in sodium chloride, … chlorine oxide. … [2] (ii) Describe, in terms of electrons, how sodium atoms and chlorine atoms change when they react together. sodium atoms … … chlorine atoms … … [2] (d) State which halogen, chlorine or iodine, reacts with aqueous sodium bromide to release bromine. Explain your answer. halogen … explanation … … [1] (e) Fig. 5.1 shows the apparatus that is used for the electrolysis of copper chloride solution, using inert electrodes. d.c. power supply positive negative electrode electrode copper chloride solution Fig. 5.1 Describe the appearance of the products at the positive electrode and the negative electrode. positive electrode … negative electrode … [2]

10 marks

Mark scheme: 5(a) gaseous to liquid to solid ; 1 5(b)(i) (protons) 17 (neutrons) 18 ; 1 5(b)(ii) nucleus ; 1 5(c)(i) (sodium chloride) ionic / electrovalent ; (chlorine oxide ) covalent ; 2 5(c)(ii) (sodium atoms) lose electrons ; (chlorine atoms) gain electrons ; 2 5(d) chlorine – no mark chlorine more reactive than bromine ; 1 5(e) at positive gas is released / bubbles produced ; at negative brown / copper-coloured solid (layer) ; 2

This question in 0654/31 Oct/Nov 2018

5 Copper and potassium are metallic elements in the fourth period of the Periodic Table. (a) (i) Using the Periodic Table on page 28, state: • the chemical symbols of copper and potassium copper … potassium … • the proton numbers of copper and potassium. copper … potassium … [2] (ii) State whether an atom of copper or an atom of potassium contains the greater number of electrons. Explain your answer. atom … explanation … … [1] (iii) An atom of copper and an atom of potassium have different mass numbers. Define the term mass number. … … [1] (b) State two reasons, other than cost, why potassium is not used to make water pipes. 1 … … 2 … … [2] (c) A student uses the apparatus shown in Fig. 5.1 to investigate what happens when copper carbonate, a green solid, is heated strongly. copper carbonate limewater heat Fig. 5.1 During heating, green copper carbonate changes to black copper oxide, and carbon dioxide bubbles through the limewater. (i) Construct the word equation for this reaction. + [1] (ii) Identify the type of chemical reaction that occurs when copper carbonate is heated. … [1] (iii) Describe the change in appearance of the limewater during the investigation. … [1] (iv) State one property of copper carbonate that is typical of a transition metal compound. … [1]

10 marks

Mark scheme: 5(a)(i) Cu K; 29 19; 2 5(a)(ii) (copper) ref. to the equality of numbers of protons and electrons; 1 5(a)(iii) (total of the) protons plus neutrons (in the nucleus of an atom); 1 5(b) potassium is too malleable / weak; potassium reacts with water; 2 5(c)(i) copper carbonate → copper oxide + carbon dioxide; 1 5(c)(ii) thermal decomposition; 1 5(c)(iii) turns milky; 1 5(c)(iv) coloured; 1

This question in 0654/32 Oct/Nov 2018

2 Chlorine and argon are gaseous elements in Period 3 of the Periodic Table. (a) State one use of chlorine. use of chlorine … … [1] (b) An argon atom contains 18 electrons. (i) State the electronic structure of argon. … [1] (ii) State, in terms of electronic structure of atoms, why argon is unreactive. … … [1] (iii) Information about the atomic structure of a particle J is shown below. number of protons in the nucleus 17 electronic structure 2,8,8 Explain why particle J is a negative chloride ion. … … … … [2] (c) Chlorine, Cl 2, combines with hydrogen, H2, to form hydrogen chloride, HCl . (i) Balance the symbol equation for this reaction. Cl 2 + H2 HCl [1] (ii) Fig. 2.1 shows the covalent bond in a molecule of hydrogen chloride. H Cl Fig. 2.1 State the number of electrons in this bond. … [1] [Total: 7]

7 marks

Mark scheme: 2(a) ref. to sterilisation of (drinking) water ; 1 2(b)(i) 2,8,8 ; 1 2(b)(ii) outer shell is full / all shells complete / the idea that electrons do not need to be lost or gained for stability ; 1 2(b)(iii) (J contains) more electrons than protons / has one extra electron/has extra electrons ; electrons are negative ; 2 2(c)(i) (Cl2 + H2 → ) 2 HCl ; 1 2(c)(ii) two / one pair ; 1

This question in 0654/31 May/June 2019

2 Fig. 2.1 shows the chemical symbols of five elements in Period 4 of the Periodic Table. A copy of the whole Periodic Table is on page 36. 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Mn Co Br Kr Fig. 2.1 (a) (i) Explain what the numbers 19 to 36 represent for the elements in Period 4 from K to Kr. … … [1] (ii) Using only the symbols shown in Fig. 2.1, identify: a metallic element … a non-metallic element … a transition metal … a halogen … the least reactive element in the period … an element that reacts violently with water. … [3] (b) An atom of phosphorus contains 15 electrons. Complete Fig. 2.2 to show the number of electrons in each shell of a phosphorus atom. One electron in each shell has been drawn for you. electron x x x Fig. 2.2 [2] (c) The elements hydrogen and oxygen combine to form water, H2O. Fig. 2.3 shows molecules in a mixture of hydrogen and oxygen. Fig. 2.4 shows molecules in water vapour. Fig. 2.3 Fig. 2.4 (i) State the formula of an oxygen molecule. … [1] (ii) Use Fig. 2.3 and Fig. 2.4 to describe one difference between a mixture of two elements and a compound of two elements. … … … … [2] [Total: 9]

9 marks

Mark scheme: 2(a)(i) this is the proton number / atomic number – the number of protons (in an atom) ; 1 2(a)(ii) K / Mn / Co Br / Kr Mn / Co Br Kr K 2 or 3 correct ; 4 or 5 correct ; 6 correct ; 3 2(b) inner shells 2.8 ; outer shell 5 ; 2 2(c)(i) O2 ; 1 2(c)(ii) mixture – different atoms not bonded to each other ; compound – different atoms bonded together ; or mixture – idea that relative amounts of different atoms not fixed ; compound – has a formula / fixed ratio of atoms ; 2

This question in 0654/32 May/June 2019

2 Fig. 2.1 shows the chemical symbols of five elements in Period 4 of the Periodic Table. A copy of the whole Periodic Table is on page 36. 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Mn Co Br Kr Fig. 2.1 (a) (i) Explain what the numbers 19 to 36 represent for the elements in Period 4 from K to Kr. … … [1] (ii) Using only the symbols shown in Fig. 2.1, identify: a metallic element … a non-metallic element … a transition metal … a halogen … the least reactive element in the period … an element that reacts violently with water. … [3] (b) An atom of phosphorus contains 15 electrons. Complete Fig. 2.2 to show the number of electrons in each shell of a phosphorus atom. One electron in each shell has been drawn for you. electron x x x Fig. 2.2 [2] (c) The elements hydrogen and oxygen combine to form water, H2O. Fig. 2.3 shows molecules in a mixture of hydrogen and oxygen. Fig. 2.4 shows molecules in water vapour. Fig. 2.3 Fig. 2.4 (i) State the formula of an oxygen molecule. … [1] (ii) Use Fig. 2.3 and Fig. 2.4 to describe one difference between a mixture of two elements and a compound of two elements. … … … … [2] [Total: 9]

9 marks

Mark scheme: 2(a)(i) this is the proton number / atomic number – the number of protons (in an atom) ; 1 2(a)(ii) K / Mn / Co Br / Kr Mn / Co Br Kr K 2 or 3 correct ; 4 or 5 correct ; 6 correct ; 3 2(b) inner shells 2.8 ; outer shell 5 ; 2 2(c)(i) O2 ; 1 2(c)(ii) mixture – different atoms not bonded to each other ; compound – different atoms bonded together ; or mixture – idea that relative amounts of different atoms not fixed ; compound – has a formula / fixed ratio of atoms ; 2

This question in 0654/33 May/June 2019

2 The Periodic Table shows the elements arranged in order of proton number. A copy of the Periodic Table is shown on page 32. (a) State the meaning of the term proton number. … … [1] (b) Three metals, X, Y and Z, are in Group 1 of the Periodic Table. Table 2.1 shows the observations when they are reacted separately with water. Table 2.1 metal observation X metal melts, gas released very quickly, coloured flame is seen Y metal melts, gas released quickly Z metal does not melt, gas released slowly (i) Identify the gas that is released when Group 1 metals react with water. … [1] (ii) Deduce which metal, X, Y or Z, has the greatest proton number. Explain your answer. metal … explanation … … … [2] (iii) Use the information in Table 2.1 to place metals X, Y and Z in order of their melting points. Explain your answer. … (highest) … … (lowest) explanation … … … [2] (c) Hydrogen peroxide is a colourless liquid. Aqueous hydrogen peroxide decomposes very slowly, releasing oxygen gas. A student adds solid manganese(IV) oxide to aqueous hydrogen peroxide and observes that oxygen gas is released at a much higher rate. oxygen aqueous gas aqueous hydrogen hydrogen peroxide peroxide and manganese(IV) oxide Fig. 2.1 (i) Describe the test for oxygen gas. … … [1] (ii) Describe the role of the manganese(IV) oxide in this reaction. … … … [2] (iii) Balance the symbol equation for the decomposition of hydrogen peroxide. ……. H2O2 ……. H2O + O2 [1] [Total: 10]

10 marks

Mark scheme: 2(a) number of protons in an atom (of the element) ; 1 2(b)(i) hydrogen / H2 ; 1 2(b)(ii) (X) X reacts most vigorously with water ; reactivity increases down Group 1 / with increasing proton number ; 2 2(b)(iii) Z (highest) Y X (lowest) ; the idea that melting point decreases down Group 1 / as reactivity increases / owtte ; 2 2(c)(i) relights glowing splint ; 1 2(c)(ii) catalyst ; speeds up reaction rate ; 2 2(c)(iii) 2H2O2 → 2H2O + O2 ; 1

This question in 0654/31 Oct/Nov 2019

5 (a) Name the type of chemical bond between: a metallic element and a non-metallic element … two non-metallic elements. … [2] (b) Fig. 5.1 shows four particle diagrams, A, B, C and D. A B Key argon atom carbon atom hydrogen atom oxygen atom C D Fig. 5.1 (i) Carbon exists in different forms. Name the form of carbon shown in diagram A. … [1] (ii) Complete the sentences to explain why diagrams A, B and C show elements and why diagram D shows a compound. Diagrams A, B and C show elements because … … … Diagram D shows a compound because … … … [2] (iii) State the formula of the compound in diagram D. … [2] (c) The element lead is separated from the compound lead(II) bromide using electrolysis as shown in Fig. 5.2. d.c. power supply – + inert electrode F inert electrode E brown gas molten lead(II) bromide strong heat Fig. 5.2 (i) Name the inert electrodes E and F in Fig. 5.2. E … F … [2] (ii) The process releases a brown gas. Name the brown gas. … [1] [Total: 10]

10 marks

Mark scheme: 5(a) ionic / electrovalent ; covalent ; 2 5(b)(i) graphite ; 1 5(b)(ii) (A, B and C are elements because) they contain only one type of atom ; (D is compound because) it shows different types of atom bonded together ; 2 5(b)(iii) C2H6O symbols correct ; subscripts correct ; 2 5(c)(i) E – cathode ; F – anode ; 2 5(c)(ii) bromine ; 1

This question in 0654/31 Oct/Nov 2019

2 Fig. 2.1 is a diagram of an atom of element Q. nucleus Fig. 2.1 (a) (i) Explain why the mass of an atom is almost the same as the mass of its nucleus. … … … [1] (ii) Use Fig. 2.1 to identify element Q. A copy of the Periodic Table is shown on page 32. Explain your answer. element … explanation … … … [2] (iii) State why element Q does not easily combine with other elements. … … [1] (b) A teacher investigates the change in mass when calcium burns in air to form calcium oxide. (i) The mass of calcium oxide produced is greater than the mass of calcium the teacher used. Explain this result. … … [1] (ii) The teacher mixes calcium oxide with water to form a solution. Predict the pH of the solution. Explain your answer. prediction … … explanation … … … [2] [Total: 7]

7 marks

Mark scheme: 2(a)(i) electrons have (virtually) zero mass ; 1 2(a)(ii) argon / Ar ; and then one from there are 18 electrons / (and so) 18 protons (in the atom) ; so the proton number / atomic number = 18 (and so is argon) ; eight outer electrons so Group VIII and three shells so third period ; 2 2(a)(iii) outer (electron) shell is full / no need to lose or gain electrons for stability / owtte ; 1 2(b)(i) mass of oxygen is added to the mass of calcium / owtte ; 1 2(b)(ii) mixture pH is >7 to 14 ; mixture is alkaline / mixture contains calcium hydroxide / it is a metal oxide / it is a basic oxide ; 2

This question in 0654/32 Oct/Nov 2019

9 (a) A battery from a mobile phone (cell phone) is analysed to see what it contains. One of the materials is the metal lithium. The sample taken from the battery consists of two types of lithium atom, lithium-6 and lithium-7. (i) Name the two types of particle in the nucleus of an atom. … and … [1] (ii) The nuclide notation for lithium-6 is written as 63 Li. State what each of the numbers in the nuclide notation represents. 6 represents … 3 represents … [2] (iii) The nuclide notation for lithium-7 is written as 73 Li. Explain why this is an isotope of lithium. … … [1] (b) The lithium battery is connected to a lamp to produce visible light. (i) Write visible light in the correct position in the incomplete electromagnetic spectrum in Fig. 9.1. gamma radio waves rays Fig. 9.1 [1] (ii) The lithium battery produces an electromotive force (e.m.f.). State the unit of e.m.f. … [1] (c) Fig. 9.2 shows the arrangement of lithium atoms in three different states of matter. Label Fig. 9.2 to identify the state represented in each diagram. … … … Fig. 9.2 [2] [Total: 8]

8 marks

Mark scheme: 9(a)(i) proton and neutron ; 1 9(a)(ii) nucleon number / mass number ; atomic number / proton number ; 2 9(a)(iii) atomic number / proton number is the same ; 1 9(b)(i) visible light in the centre box ; 1 9(b)(ii) Volts, V ; 1 9(c) solid then gas then liquid 1 mark for 1 correct ; 2 marks for all 3 correct ; 2

This question in 0654/32 Oct/Nov 2019

2 (a) Fig. 2.1 shows the symbols of six elements and six statements about these elements. On Fig. 2.1 draw one straight line from each symbol to the correct statement. One line has already been drawn for you. symbol statement a halogen Al the metal obtained Ca from bauxite the metal combined F in limestone the element used to C make sulfuric acid the element in diamond K a very reactive metal S Fig. 2.1 [3] (b) The chemical symbols of an atom of beryllium and an atom of boron are shown in Fig. 2.2. nucleon number 9 11 Be B proton number 4 5 Fig. 2.2 Complete Table 2.1 to show the numbers of neutrons and electrons in these atoms. Table 2.1 neutrons electrons Be B [2] (c) Sodium and chlorine combine to form sodium chloride. Fig. 2.3 shows the electronic structure of an atom of sodium and of an atom of chlorine. sodium atom chlorine atom Fig. 2.3 Complete Fig. 2.4 to show the electronic structures of the ions that form from these atoms. sodium ion chloride ion Fig. 2.4 [2] (d) Fig. 2.5 shows apparatus a student uses to produce a neutral solution of sodium chloride. Apparatus F contains a dilute acid which is added slowly to an alkaline solution contained in the beaker. pH meter apparatus F pH dilute acid tap to allow acid to run out beaker alkaline solution Fig. 2.5 (i) Name apparatus F. … [1] (ii) State the alkaline solution and the dilute acid that react to produce sodium chloride. alkaline solution … dilute acid … [2] (iii) Suggest a value of the pH of the solution in the beaker before any acid is added. pH = … [1] [Total: 11]

11 marks

Mark scheme: 2(a) 1 correct ; 3 correct ;; 5 correct ;;; 3 2(b) n e Be 5 4 B 6 5 ;; 2 2(c) sodium ion correct ; chloride ion correct ; 2 2(d)(i) burette ; 1 Question Answer Marks 2(d)(ii) sodium hydroxide ; hydrochloric (acid) ; 2 2(d)(iii) >7 up to 14 ; 1

This question in 0654/33 Oct/Nov 2019

5 Non-metallic elements are placed in groups towards the right hand side of the Periodic Table. (a) Describe what is meant by a group in the Periodic Table. … … [1] (b) Fig. 5.1 shows the chemical symbols of five non-metallic elements. Cl Ar N P S Fig. 5.1 (i) One of the symbols in Fig. 5.1 is not in the same period of the Periodic Table as the others. Identify the symbol and explain your answer. symbol … explanation … … … [1] (ii) Select two elements from Fig. 5.1 that are contained in fertilisers. … and … [1] (iii) State one reason why fertiliser is added to soil. … … [1] (c) Select one element from Fig. 5.1 that is used to treat water to make it safe to drink. Explain how it does this. element … explanation … … [2] (d) Fig. 5.2 shows the electronic structures of atoms of argon, chlorine and potassium. argon chlorine potassium Fig. 5.2 (i) Argon does not react with potassium. Explain why. Use ideas about electronic structures in your answer. … … … [2] (ii) Potassium reacts with chlorine to form potassium chloride. Describe how the electronic structures of a potassium atom and of a chlorine atom change when potassium and chlorine react. change in potassium … … change in chlorine … … [2] (iii) Name the type of chemical bonding in potassium chloride. … [1] [Total: 11]

11 marks

Mark scheme: 5(a) vertical column of elements / elements whose atoms have same number of outer electrons ; 1 5(b)(i) (N) idea that the other four are in same horizontal row ; 1 Question Answer Marks 5(b)(ii) two from N / P / S ; 1 5(b)(iii) improves fertility / increases crop yield (size) / to replenish nutrients ; 1 5(c) Cl / chlorine ; sterilises the water / kills (harmful) microorganisms ; 2 5(d)(i) argon has full outer shell (of electrons) ; filled shell is stable / means argon is inert / does not lose or gain electrons to become stable ; 2 5(d)(ii) (potassium atom) loses one electron ; changes from 2.8.8.1 to 2.8.8 ; (chlorine atom ) gains one electron; changes from 2.8.7. to 2.8.8 ; 2 5(d)(iii) ionic / electrovalent ; 1

This question in 0654/31 May/June 2020

2 Calcium is in Group II of the Periodic Table. (a) (i) An atom of calcium has a proton number (atomic number) of 20 and a nucleon number (mass number) of 40. For this calcium atom state: the number of neutrons it contains … its electronic structure. … [2] (ii) Explain why atoms are electrically neutral. Use ideas about protons and electrons. … … … … … [3] (iii) State where the neutrons are in an atom. … [1] (b) The main compound in limestone is calcium carbonate, CaCO3. (i) State the number of different elements in calcium carbonate. … [1] (ii) Complete the word equation for the reaction between calcium carbonate and dilute hydrochloric acid. calcium hydrochloric + + + carbonate acid [2] (iii) Rainwater is slightly acidic. The acid in rainwater reacts very slowly with limestone rocks. Suggest two reasons for the very slow rate of reaction between rainwater and limestone rocks. 1 … … 2 … … [2] [Total: 11]

11 marks

Mark scheme: 2(a)(i) 20 ; 2,8,8,2 ; 2 2(a)(ii) the idea that numbers of protons and electrons are equal ; protons are positive electrons are negative ; total positive charge balances total negative charge ; 3 2(a)(iii) nucleus ; 1 2(b)(i) 3 ; 1 2(b)(ii) calcium chloride ; carbon dioxide + water ; 2 Question Answer Marks 2(b)(iii) temperature is (on average) low ; concentration of acid in rain water is low ; 2

This question in 0654/32 May/June 2020

2 Calcium is in Group II of the Periodic Table. (a) (i) An atom of calcium has a proton number (atomic number) of 20 and a nucleon number (mass number) of 40. For this calcium atom state: the number of neutrons it contains … its electronic structure. … [2] (ii) Explain why atoms are electrically neutral. Use ideas about protons and electrons. … … … … … [3] (iii) State where the neutrons are in an atom. … [1] (b) The main compound in limestone is calcium carbonate, CaCO3. (i) State the number of different elements in calcium carbonate. … [1] (ii) Complete the word equation for the reaction between calcium carbonate and dilute hydrochloric acid. calcium hydrochloric + + + carbonate acid [2] (iii) Rainwater is slightly acidic. The acid in rainwater reacts very slowly with limestone rocks. Suggest two reasons for the very slow rate of reaction between rainwater and limestone rocks. 1 … … 2 … … [2] [Total: 11]

11 marks

Mark scheme: 2(a)(i) 20 ; 2,8,8,2 ; 2 2(a)(ii) the idea that numbers of protons and electrons are equal ; protons are positive electrons are negative ; total positive charge balances total negative charge ; 3 2(a)(iii) nucleus ; 1 2(b)(i) 3 ; 1 2(b)(ii) calcium chloride ; carbon dioxide + water ; 2 Question Answer Marks 2(b)(iii) temperature is (on average) low ; concentration of acid in rain water is low ; 2

This question in 0654/33 May/June 2020

5 (a) Lithium, sodium and potassium are alkali metal elements in the Periodic Table. Table 5.1 shows the melting points of lithium, sodium and potassium. Table 5.1 metal melting point / °C lithium 181 sodium 98 potassium 64 State the trend in the melting points of the elements from lithium to potassium. … [1] (b) An atom of sodium has a nucleon number (mass number) of 23 and a proton number (atomic number) of 11. Fig. 5.1 shows the structure of an atom of sodium. electron … … Fig. 5.1 (i) On Fig. 5.1, complete the labels for the sodium atom. [2] (ii) State the electronic structure for this sodium atom. … [1] (c) Sodium and chlorine react to form sodium chloride. Fig. 5.2 shows the electronic structure of a sodium atom and a chlorine atom. Na Cl sodium atom chlorine atom Fig. 5.2 Draw diagrams to show the electronic structures of a sodium ion and of a chloride ion when sodium reacts with chlorine. Include the charge for each ion. sodium ion chloride ion [3] (d) Sodium and chlorine are elements. Sodium chloride is a compound. Describe the difference between an element and a compound. … … … [2] [Total: 9]

9 marks

Mark scheme: 5(a) melting point decreases (down group) ; 1 5(b)(i) proton; neutron; 2 Question Answer Marks 5(b)(ii) 2.8.1; 1 5(c) sodium ion 2.8 ; chloride ion 2.8.8 ; sodium has positive charge and chloride has negative charge indicated; 3 5(d) an element contains only one type of atom; a compound contains two or more elements (chemically) combined / bonded; 2

This question in 0654/32 Feb/March 2021

8 (a) Fig. 8.1 shows three molecules A, B and C. H H H H H H C C O H H C H C C H H H H H A B C Fig. 8.1 State the formula of the substance that reacts with molecule C to make molecule A. … [1] (b) Molecule B, CH4, is methane which is a compound. Methane contains the elements carbon and hydrogen. Use this information to explain the difference between an element and a compound. … … … [2] (c) State the two products made when methane undergoes complete combustion in oxygen. 1 … 2 … [2] (d) The combustion of methane is an exothermic reaction. State what is meant by exothermic. … … [1] (e) An atom of carbon has a nucleon number (mass number) of 12 and a proton number (atomic number) of 6. An atom of hydrogen has a nucleon number (mass number) of 1 and a proton number (atomic number) of 1. (i) State the number of electrons in an atom of carbon and in an atom of hydrogen. carbon … hydrogen … [1] (ii) State the number of neutrons in this atom of hydrogen. … [1] (f) Complete the dot‑and‑cross diagram in Fig. 8.2 to show the bonding in a methane, CH4, molecule. H H C H H Fig. 8.2 [2] [Total: 10]

10 marks

Mark scheme: 8(a) H2O ; 1 8(b) an element (e.g. carbon) contains only one type of atom ; a compound (e.g. methane) contains two or more elements / different atoms chemically combined ; 2 8(c) carbon dioxide ; water ; 2 8(d) releases thermal energy ; 1 8(e)(i) carbon 6 and hydrogen 1 ; 1 8(e)(ii) zero ; 1 Question Answer Marks 8(f) one shared pair seen ; all correct ;; 2

This question in 0654/31 May/June 2021

8 (a) An atom of aluminium has a proton number of 13 and nucleon number of 27. (i) State what is meant by the term nucleon number. … … [1] (ii) Describe the electronic structure of an atom of aluminium. You may wish to draw a diagram to help your answer. … … [2] (b) Aluminium is extracted from its ore by electrolysis. (i) Name one ore from which aluminium is extracted. … [1] (ii) Electrolysis results in a chemical change. Explain what is meant by a chemical change. … … [1] (c) Aluminium alloys are used in aircraft parts. (i) State what is meant by the term alloy. … … [1] (ii) State why aluminium alloys are used in aircraft parts. … … [1] (iii) State why aluminium is used in the form of alloys rather than as pure aluminium. … … [1] (iv) Describe and explain one other use of aluminium. use … explanation … [2] [Total: 10]

10 marks

Mark scheme: 8(a)(i) number of protons and neutrons in an atom ; 1 8(a)(ii) 13 electrons ; 2.8.3 ; 2 8(b)(i) bauxite ; 1 8(b)(ii) new substance(s) produced ; 1 8(c)(i) mixture of metals / mixture of a metal and another element ; 1 8(c)(ii) low density ; 1 8(c)(iii) stronger ; 1 8(c)(iv) food containers / drink cans ; resistant to corrosion ; 2

This question in 0654/32 Oct/Nov 2021

5 (a) An atom of iron has a proton number of 26 and a nucleon number of 56. (i) State the number of electrons in this atom of iron. number of electrons = … [1] (ii) State the number of neutrons in this atom of iron. number of neutrons = … [1] (iii) Another atom of iron has a nucleon number of 54. State the proton number of this atom of iron. proton number = … [1] (b) Fig. 5.1 shows an aqueous solution of iron(III) chloride. Fig. 5.1 A student tests the solution to confirm that the label is correct. State the test for aqueous iron(III) ions (Fe 3+) and give the observation for a positive result. test … observation … … [2] (c) Stainless steel is an alloy of iron. (i) Define the term alloy. … … [1] (ii) State one use for stainless steel. … [1] (iii) State the two conditions needed for the rusting of iron. 1 … 2 … [2] (iv) Describe and explain one method of rust prevention. … … … [2] [Total: 11]

11 marks

Mark scheme: 5(a)(i) 26; 1 5(a)(ii) 30; 1 5(a)(iii) 26; 1 5(b) sodium hydroxide solution; orange / brown ppt; 2 5(c)(i) mixture of metals / mixture of a metal and another element; 1 5(c)(ii) cutlery / chemical plant; 1 5(c)(iii) (presence of) oxygen; (presence of) water; 2 Question Answer Marks 5(c)(iv) painting / galvanising / plating / greasing; relevant explanation for method chosen (e.g. stops water / oxygen); 2

This question in 0654/32 Feb/March 2022

11 (a) Fig. 11.1 shows part of Group I of the Periodic Table. 3 Li lithium 7 11 Na sodium 23 19 K potassium 39 37 Rb rubidium 85 Fig. 11.1 (i) State the electronic structure of a potassium atom. … [1] (ii) Describe how the electronic structure of potassium is related to its group number. … … [1] (iii) The proton number of a potassium atom is 19. The nucleon number of this potassium atom is 39. State the numbers of electrons and neutrons in this potassium atom. electrons … neutrons … [2] (iv) Complete Table 11.1 to show the charges and approximate relative masses of an electron and a neutron. Table 11.1 particle charge relative mass proton +1 1 electron … … neutron … … [2] (b) Potassium, K, is an element. Potassium hydroxide, KOH, is a compound. Explain the difference between an element and a compound. element … … compound … … [2] (c) Balance the symbol equation for the reaction between potassium and water. … K + … H2O … KOH + H2 [2] [Total: 10]

10 marks

Mark scheme: 11(a)(i) 2.8.8.1; 1 11(a)(ii) number of outer shell electrons is the same as group number; 1 11(a)(iii) electrons = 19; neutrons = 20; 2 11(a)(iv) particle charge relative mass proton + 1 1 electron –1 0 or 1 / 2000 neutron 0 1 2 11(b) element – contains only one type of atom; compound –contains two or more elements chemically combined ; 2 11(c) 2K + 2H2O  2KOH + H2 LHS 1 ; RHS 1; 2

This question in 0654/31 May/June 2022

8 (a) An atom of copper has a proton number of 29 and a nucleon number of 63. (i) State the number of electrons in this copper atom. … [1] (ii) State the number of neutrons in this copper atom. … [1] (b) Copper oxide is heated with carbon. Copper and carbon dioxide are made. (i) Write the word equation for this reaction. + + [1] (ii) In this reaction, reduction of copper in the copper oxide occurs. Describe what is meant by the term reduction. … … [1] (iii) Explain why copper oxide is described as a basic oxide. … … [1] (c) Copper is a transition element. Transition elements have high densities, high melting points and high boiling points. They are all metals. State one other property of a transition element. … … [1] (d) (i) Brass is a mixture of copper and zinc. State the term used to describe a mixture of metals. … [1] (ii) Brass is more malleable than either copper or zinc. State the meaning of the term malleable. … [1] (iii) State the symbols of both copper and zinc. copper symbol … zinc symbol … [1] (e) A metal key is covered with a layer of copper by electroplating. (i) The key is an electrode. State which electrode is the key. … [1] (ii) Suggest a suitable electrolyte for electroplating the key. … [1] [Total: 11]

11 marks

Mark scheme: 8(a)(i) 29 ; 1 8(a)(ii) 34 ; 1 8(b)(i) copper oxide + carbon → copper + carbon dioxide ; 1 8(b)(ii) loss of oxygen ; 1 8(b)(iii) metal oxide / reacts with an acid to make a salt / neutralises an acid ; 1 8(c) any one from: 1 forms coloured compounds ; acts as catalyst ; variable valency ; 8(d)(i) alloy ; 1 8(d)(ii) can be beaten into shape; 1 8(d)(iii) Cu and Zn ; 1 8(e)(i) cathode / negative ; 1 8(e)(ii) copper (II) sulfate ; 1

This question in 0654/31 Oct/Nov 2022

11 (a) (i) An atom of calcium has 20 protons and 20 neutrons. State the number of electrons in this calcium atom. … [1] (ii) State the number of electrons in one calcium ion, Ca2+. … [1] (b) Limestone (calcium carbonate) and lime (calcium oxide) are both calcium compounds. Fig. 11.1 shows a limekiln in which calcium carbonate thermally decomposes to make calcium oxide and carbon dioxide. waste gases containing carbon dioxide calcium carbonate thermally decomposing carbon burning to provide thermal energy air Fig. 11.1 (i) Write the word equation for the thermal decomposition of calcium carbonate. … [1] (ii) The mass of calcium oxide made in this reaction is always less than the mass of calcium carbonate used. Suggest why. … … [1] (iii) The decomposition of calcium carbonate to calcium oxide is an endothermic reaction. State the meaning of the term endothermic. … … [1] (iv) One use for limestone is in the production of lime. State one other use of limestone. … … [1] (v) Suggest why the calcium carbonate is broken into small pieces before being thermally decomposed. … … … [2] (c) Calcium carbonate has the formula CaCO3. (i) State the number of different elements shown in this formula. … [1] (ii) State the total number of atoms shown in this formula. … [1] [Total: 10]

10 marks

Mark scheme: 11(a)(i) 20 (electrons) ; 1 11(a)(ii) 18 (electrons) ; 1 11(b)(i) calcium carbonate  calcium oxide  carbon dioxide ; 1 11(b)(ii) carbon dioxide released ; 1 11(b)(iii) (thermal) energy taken in ; 1 11(b)(iv) neutralising acidified soil ; 1 Question Answer Marks 11(b)(v) to increase surface area ; so that reaction is faster ; 2 11(c)(i) three ; 1 11(c)(ii) five ; 1

This question in 0654/32 May/June 2023

11 (a) (i) An atom of calcium has 20 protons and 20 neutrons. State the number of electrons in this calcium atom. … [1] (ii) State the number of electrons in one calcium ion, Ca2+. … [1] (b) Limestone (calcium carbonate) and lime (calcium oxide) are both calcium compounds. Fig. 11.1 shows a limekiln in which calcium carbonate thermally decomposes to make calcium oxide and carbon dioxide. waste gases containing carbon dioxide calcium carbonate thermally decomposing carbon burning to provide thermal energy air Fig. 11.1 (i) Write the word equation for the thermal decomposition of calcium carbonate. … [1] (ii) The mass of calcium oxide made in this reaction is always less than the mass of calcium carbonate used. Suggest why. … … [1] (iii) The decomposition of calcium carbonate to calcium oxide is an endothermic reaction. State the meaning of the term endothermic. … … [1] (iv) One use for limestone is in the production of lime. State one other use of limestone. … … [1] (v) Suggest why the calcium carbonate is broken into small pieces before being thermally decomposed. … … … [2] (c) Calcium carbonate has the formula CaCO3. (i) State the number of different elements shown in this formula. … [1] (ii) State the total number of atoms shown in this formula. … [1] [Total: 10]

10 marks

Mark scheme: 11(a)(i) 20 (electrons) ; 1 11(a)(ii) 18 (electrons) ; 1 11(b)(i) calcium carbonate  calcium oxide  carbon dioxide ; 1 11(b)(ii) carbon dioxide released ; 1 11(b)(iii) (thermal) energy taken in ; 1 11(b)(iv) neutralising acidified soil ; 1 Question Answer Marks 11(b)(v) to increase surface area ; so that reaction is faster ; 2 11(c)(i) three ; 1 11(c)(ii) five ; 1

This question in 0654/33 May/June 2023

2 (a) Air is a mixture of gases. Fig. 2.1 shows two pie charts representing samples of air, A and B. other gases other gases oxygen oxygen gas X gas X sample A sample B Fig. 2.1 (i) State which sample, A or B, represents clean air. Explain your answer. sample … explanation … … [1] (ii) Identify gas X. … [1] (b) Sulfur dioxide is a common pollutant found in air. (i) State one adverse effect of sulfur dioxide on the health of humans. … … [1] (ii) State one source of sulfur dioxide in the air. … [1] (iii) State one other common pollutant gas found in the air. … [1] (iv) Sulfur dioxide dissolves in rainwater to make acid rain. Suggest a pH value for acid rain. pH = … [1] (v) Farmers need to treat acidic soil to neutralise the acidity. State the chemical substance used by farmers to treat soil acidity. … [1] (c) An atom of sulfur has an electronic structure 2, 8, 6. (i) On Fig. 2.2, complete the electronic structure for this atom of sulfur. S Fig. 2.2 [1] (ii) Suggest how many electrons this sulfur atom gains to become a sulfide ion S2–. … [1] [Total: 9]

9 marks

Mark scheme: 2(a)(i) sample A (no mark) 1 idea that proportion of gases (other than Nitrogen) is correct ; ORA about sample B 2(a)(ii) nitrogen ; 1 2(b)(i) respiratory problems ; 1 2(b)(ii) combustion of fossil fuels (containing sulfur) / volcanoes ; 1 2(b)(iii) carbon monoxide / nitrogen oxides ; 1 2(b)(iv) 3-6 ; 1 2(b)(v) lime(stone) / CaCO3 / CaO / Ca(OH)2 ; 1 2(c)(i) 2 electrons in first shell and 1 8 electrons in 2nd shell and 6 electrons in 3rd shell ; 2(c)(ii) 2 ; 1

This question in 0654/31 Oct/Nov 2023

2 (a) Chlorine, bromine and iodine are halogens in Group VII of the Periodic Table. Some of these statements about the halogens are correct and some are incorrect. Place a tick (✓) in the boxes next to the correct statements. the halogens are elements the halogens exist as diatomic molecules the halogens form covalent molecules with metals the reactivity of the halogens increases down the group [2] (b) A chlorine atom has a nucleon number of 37 and has 17 electrons. (i) Determine the number of protons and the number of neutrons in this chlorine atom. number of protons = … number of neutrons = … [2] (ii) State the part of the atom that contains the protons and neutrons. … [1] (c) Chlorine is made during the electrolysis of concentrated aqueous sodium chloride as shown below in Fig. 2.1. graphite electrodes gaseous products concentrated aqueous sodium chloride Fig. 2.1 (i) State the electrode at which chlorine forms during this process. … [1] (ii) State the other gaseous product of this electrolysis. … [1] (iii) Explain why graphite is used to make the electrodes. … [1] (iv) Explain why electrolysis is an example of a chemical change and not a physical change. … … [1] (d) Explain why the drinking water supply for a town is treated with chlorine. … … [1] [Total: 10]

10 marks

Mark scheme: 2(a) 2 the halogens are elements  the halogens exist as diatomic molecules  ;; 2 ticks 2 correct = 2 marks 3 ticks 2 correct = 1 mark 2 ticks 1 correct = 1 mark 1 tick 1 correct = 1 mark 4 ticks 2 correct = 0 marks 2(b)(i) protons = 17 ; 2 neutrons = 20 ; 2(b)(ii) nucleus ; 1 2(c)(i) anode / positive ; 1 2(c)(ii) hydrogen ; 1 2(c)(iii) it is inert / will not react / good electrical conductor ; 1 2(c)(iv) new substances formed / cannot be reversed ; 1 2(d) kills microbes / sterilise water ; 1

This question in 0654/32 Oct/Nov 2023

2 (a) A list of processes is shown. chromatography combustion cracking electroplating fermentation filtration oxidation polymerisation rusting Identify, from the list, the process that is used to: (i) break down large hydrocarbon alkane molecules into smaller alkene and smaller alkane molecules. … [1] (ii) make ethanol from glucose. … [1] (iii) make long chain molecules from small monomer units. … [1] (iv) separate a mixture of dyes. … [1] (v) cover a metal with a layer of copper. … [1] (b) Sodium chloride is made by reacting an acid with a base. State the name of the acid and the base that are used. acid … base … [2] (c) An atom of sodium has 11 electrons. A sodium ion has the symbol Na+. Complete Fig. 2.1 to show the electronic structures of a sodium atom and a sodium ion. The first electron shell has been completed for you. sodium atom sodium ion Fig. 2.1 [2] (d) Sodium and chlorine are both in Period 3 of the Periodic Table. Use words from the list to complete the sentence to describe the changes in metallic nature across a period in the Periodic Table. Each word may be used once, more than once or not at all. left metallic non-metallic right Going from … to … , the elements change from … to … . [1] [Total: 10]

10 marks

Mark scheme: 2(a)(i) cracking ; 1 2(a)(ii) fermentation ; 1 2(a)(iii) polymerisation ; 1 2(a)(iv) chromatography ; 1 2(a)(v) electroplating ; 1 2(b) (dilute) hydrochloric acid ; 2 (aqueous) sodium hydroxide ; 2(c) sodium atom 2.8.1 ; 2 sodium ion 2.8 ; 2(d) left right metallic non-metallic ; 1 or right left non-metallic metallic

This question in 0654/32 Feb/March 2024

11 (a) A calcium atom has a proton number of 20 and a nucleon number of 40. Deduce the number of protons, neutrons and electrons in this atom of calcium. number of protons … number of neutrons … number of electrons … [3] (b) When calcium atoms react, they change into calcium ions, Ca2+. Describe how calcium atoms change into calcium ions. … … … [2] (c) Lime is produced from limestone, calcium carbonate, by thermal decomposition. (i) State the chemical name for lime. … [1] (ii) State the name of the gas formed in this thermal decomposition reaction. … [1] (iii) Explain why farmers spread limestone onto soil that is used for growing crops. … … [1] (d) The main compound in limestone is calcium carbonate, CaCO3. (i) State the number of different elements in calcium carbonate. … [1] (ii) State the total number of atoms shown in the formula CaCO3. … [1] [Total: 10]

10 marks

Mark scheme: 11(a) protons = 20 ; neutrons = 20 ; electrons = 20 ; 3 11(b) loses electrons ; 2 electrons ; 2 11(c)(i) calcium oxide ; 1 11(c)(ii) carbon dioxide ; 1 11(c)(iii) neutralise acidic soil ; 1 11(d)(i) 3 ; 1 11(d)(ii) 5 ; 1

This question in 0654/31 May/June 2024

2 (a) The list gives the names of seven elements. calcium carbon copper oxygen nitrogen potassium sulfur Answer the questions about these elements. Each element may be used once, more than once or not at all. State which element: (i) is in Group I of the Periodic Table. … [1] (ii) is in diamond. … [1] (iii) is 78% of clean air. … [1] (iv) gives a lilac flame test. … [1] (v) is used in electroplating. … [1] (vi) is used in the manufacture of sulfuric acid. … [1] (b) Atoms contain protons, neutrons and electrons. State which of these particles: are in shells around the nucleus … have a positive charge … have the smallest mass. … [3] [Total: 9]

9 marks

Mark scheme: 2(a)(i) potassium ; 1 2(a)(ii) carbon ; 1 2(a)(iii) nitrogen ; 1 2(a)(iv) potassium ; 1 2(a)(v) copper ; 1 2(a)(vi) sulfur ; 1 2(b) electrons ; protons ; electron ; 3

This question in 0654/32 May/June 2024

2 (a) The list gives the names of seven elements. calcium carbon copper oxygen nitrogen potassium sulfur Answer the questions about these elements. Each element may be used once, more than once or not at all. State which element: (i) is in Group I of the Periodic Table. … [1] (ii) is in diamond. … [1] (iii) is 78% of clean air. … [1] (iv) gives a lilac flame test. … [1] (v) is used in electroplating. … [1] (vi) is used in the manufacture of sulfuric acid. … [1] (b) Atoms contain protons, neutrons and electrons. State which of these particles: are in shells around the nucleus … have a positive charge … have the smallest mass. … [3] [Total: 9]

9 marks

Mark scheme: 2(a)(i) potassium ; 1 2(a)(ii) carbon ; 1 2(a)(iii) nitrogen ; 1 2(a)(iv) potassium ; 1 2(a)(v) copper ; 1 2(a)(vi) sulfur ; 1 2(b) electrons ; protons ; electron ; 3

This question in 0654/33 May/June 2024

11 (a) The proton numbers and nucleon numbers of carbon and hydrogen are shown in Table 11.1. Table 11.1 proton number nucleon number carbon 6 12 hydrogen 1 1 (i) State the number of neutrons in a carbon atom and the number of neutrons in a hydrogen atom. carbon … hydrogen … [2] (ii) State the number of electrons in a carbon atom. … [1] (b) (i) State the difference between a saturated hydrocarbon and an unsaturated hydrocarbon. … … [1] (ii) Aqueous bromine is used to show the difference between a saturated hydrocarbon and an unsaturated hydrocarbon. Describe the result of the test with a saturated hydrocarbon. … … [1] (c) Fig. 11.1 shows the apparatus used for the catalytic cracking of a saturated hydrocarbon. catalyst reaction vessel saturated mixture of saturated hydrocarbons and unsaturated hydrocarbons Fig. 11.1 (i) State the purpose of the catalyst in the cracking of a saturated hydrocarbon. … … [1] (ii) Cracking is an endothermic reaction. State what is meant by an endothermic reaction. … … … [1] (d) The complete combustion of hydrocarbons produces the greenhouse gas carbon dioxide. (i) Name one other greenhouse gas. … [1] (ii) Identify the gas in the air that reacts with hydrocarbons during combustion. … [1] (iii) Carbon dioxide is one of the gases found in clean air. State the name of the two gases found in clean air in the greatest proportions. 1 … 2 … [2] [Total: 11]

11 marks

Mark scheme: 11(a)(i) carbon = 6 ; 2 hydrogen = 0 ; 11(a)(ii) 6 ; 1 11(b)(i) unsaturated has a C=C double bond ; 1 11(b)(ii) aqueous bromine remains orange ; 1 11(c)(i) speed up the reaction ; 1 11(c)(ii) temperature decreases / thermal energy is absorbed (from the surroundings) ; 1 11(d)(i) methane ; 1 11(d)(ii) oxygen ; 1 11(d)(iii) oxygen ; 2 nitrogen ;

This question in 0654/32 Oct/Nov 2024

11 (a) The proton numbers and nucleon numbers of carbon and hydrogen are shown in Table 11.1. Table 11.1 proton number nucleon number carbon 6 12 hydrogen 1 1 (i) State the number of neutrons in a carbon atom and the number of neutrons in a hydrogen atom. carbon … hydrogen … [2] (ii) State the number of electrons in a carbon atom. … [1] (b) (i) State the difference between a saturated hydrocarbon and an unsaturated hydrocarbon. … … [1] (ii) Aqueous bromine is used to show the difference between a saturated hydrocarbon and an unsaturated hydrocarbon. Describe the result of the test with a saturated hydrocarbon. … … [1] (c) Fig. 11.1 shows the apparatus used for the catalytic cracking of a saturated hydrocarbon. catalyst reaction vessel saturated mixture of saturated hydrocarbons and unsaturated hydrocarbons Fig. 11.1 (i) State the purpose of the catalyst in the cracking of a saturated hydrocarbon. … … [1] (ii) Cracking is an endothermic reaction. State what is meant by an endothermic reaction. … … … [1] (d) The complete combustion of hydrocarbons produces the greenhouse gas carbon dioxide. (i) Name one other greenhouse gas. … [1] (ii) Identify the gas in the air that reacts with hydrocarbons during combustion. … [1] (iii) Carbon dioxide is one of the gases found in clean air. State the name of the two gases found in clean air in the greatest proportions. 1 … 2 … [2] [Total: 11]

11 marks

Mark scheme: 11(a)(i) carbon = 6 ; 2 hydrogen = 0 ; 11(a)(ii) 6 ; 1 11(b)(i) unsaturated has a C=C double bond ; 1 11(b)(ii) aqueous bromine remains orange ; 1 11(c)(i) speed up the reaction ; 1 11(c)(ii) temperature decreases / thermal energy is absorbed (from the surroundings) ; 1 11(d)(i) methane ; 1 11(d)(ii) oxygen ; 1 11(d)(iii) oxygen ; 2 nitrogen ;

This question in 0654/33 Oct/Nov 2024

8 (a) The element calcium is represented on the Periodic Table as shown. 20 Ca calcium 40 The symbol for a calcium ion is Ca2+. (i) State the number of protons in this calcium ion. … [1] (ii) State the number of electrons the calcium atom loses when it becomes a calcium ion. … [1] (b) Calcium carbonate reacts with dilute sulfuric acid. The symbol equation for the reaction is CaCO3 + H2SO4 CaSO4 + CO2 + H2O (i) Carbon dioxide is one of the products of the reaction. State the names of the other two products of the reaction. 1 … 2 … [2] (ii) 1.00 g of calcium carbonate makes 240 cm3 of carbon dioxide gas at room temperature and pressure. Calculate the mass of calcium carbonate needed to make 360 cm3 of carbon dioxide gas at room temperature and pressure. mass of calcium carbonate = … g [1] (c) Identify which of the changes decrease the rate of the reaction between calcium carbonate and dilute sulfuric acid. Place ticks (3) in the boxes next to the changes that decrease the rate of reaction. decrease the concentration of the dilute sulfuric acid use larger pieces of calcium carbonate increase the temperature of the dilute sulfuric acid use a catalyst [2] (d) Calcium carbonate is a solid. Carbon dioxide is a gas. Table 8.1 shows a list of properties for solids and gases. Complete Table 8.1 by identifying which properties refer to a solid (S) and which properties refer to a gas (G). One has been done for you. Table 8.1 property solid (S) or gas (G) able to be compressed able to diffuse able to flow G has a fixed shape has a fixed volume [2] [Total: 9]

9 marks

Mark scheme: 8(a)(i) 20 ; 1 8(a)(ii) 2 ; 1 8(b)(i) calcium sulfate ; 2 water ; 8(b)(ii) 1.5(0) (g) 1 2 decrease the concentration of the dilute sulfuric acid ✓ 8(c) use larger pieces of calcium carbonate ✓ increase the temperature of the dilute sulfuric acid use a catalyst 1 mark for each correct answer 3 boxes ticked – 1 incorrect – 1 mark 3 boxes ticked – 2 incorrect – 0 marks 4 boxes ticked – 0 marks 8(d) column completed top to bottom 2 G, G, (G), S, S 2 or 3 correct – 1 mark all correct – 2 marks

This question in 0654/31 Oct/Nov 2025