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1 Group 1 Mark Scheme Level Edexcel Subject Chemistry Exam Board GCSE(9-1) Topic Groups in the Periodic Table Sub Topic Group 1 Booklet Mark Scheme Time Allowed: 51 minutes Score: /42 Percentage: /100

2 1(a) Answer D Mark 1(b) An explanation linking two of the following reaction produces heat/exothermic (sodium) has low melting point (sodium) has low density/density less than water ignore sodium floats on water Answer 1(c) 2Na + 2H 2 O 2NaOH + H 2 LHS formulae RHS formulae balancing correct formulae ensure that 2 is subscript at most half the size of H and cases are correct Mark (3)

3 QWC *1(d) Indicative content similarities both in the same group/group 1/alkali metal react in a similar way same number of outer electrons/one outer electron both produce hydrogen/fizz (when reacted with water) both produce hydroxide/alkaline solution (when reacted with water) differences potassium more reactive potassium catches on fire/lilac flame potassium outer electron further from nucleus potassium has more shells potassium has more shielding potassium has less attraction of outer electron by nucleus potassium outer electron more easily lost Mar k (6) Level 0 No rewardable content 1 1- a limited explanation e.g. both in group 1 because one electron in outer shell the answer communicates ideas using simple language and uses limited scientific terminology spelling, puncuation and grammar are used with limited accuracy 2 3- a simple explanation e.g. sodium and potassium have similar reactions because they are in the same group but potassium is more reactive. the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, puncuation and grammar are used with some accuracy 3 5- a detailed explanation e.g. sodium and potassium have similar reactions because they are both have one outer electron but potassium is more reactive because its outer electron is more easily lost because it has an extra shell of electrons causing the attraction of the nucleus to be reduced the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, puncuation and grammar are used with few errors

4 2(a)(i) soft / low melting point / low boiling point easily cut with a knife = soft low density malleable solid at room temp. ignore float on water reject chemical properties 2(a)(ii) An explanation linking (all have) one electron in outer shell one outer electron = 2 marks group number shows number of electrons in outer shell = 2 marks same number of electrons in outer shell = 1 mark incorrect number of electrons in the outer shell = 1 mark accept outer orbit / highest energy level in place of outer shell

5 2(b)(i) A description including any two of effervescence / fizzing / bubbles potassium floats moves (on surface) potassium forms ball / melts potassium decreases in size / disappears / dissolves (lilac) flame / catches fire spits / explodes / sparks ignore ignites ignore smoke 2(b)(ii) D : 2K + 2 H 2 O 2KOH + H 2 2(c) An explanation linking any two of increasing {size /radius (of atom) / number of shells} increased shielding (of outer electron) less attraction for (outer) electron easier to remove (outer) electron

6 Answers Acceptable Answers Mark 3 (a) D is inert 3(b) Answers Acceptable Answers Mark An explanation linking Any mention of intermolecular forces/covalent bonds/ionic bonds (0) {atoms/cations/ions} are in {layers /sheets} { layers/sheets} can {slide/slip/ move/roll} (over each other) Accept a diagram showing layers with labelled {atoms/cations/ions} Ignore rows /lines/ lattice Do not allow electrons can slide/slip/move over each other Ignore references to delocalised electrons Answers Acceptable Answers Mark 3 (c) P Br Allow PBr 3 with no working or incorrect working (3) mass 3.1/31(= 0.1) (=0.3) 24/80 PBr 3 with some correct working (3) A r Accept Br 3P ratio 1 3 formula PBr 3 Allow TE for second and third marks e.g. P Br 31/3.1(= 10) (0) 80/24 (= 3.33) 3 1 P 3Br P 3Br with no working (0)

7 Indicative content QWC 3(d) A description / explanation including some of the following points Mark (6) Description effervescence / fizzing / bubbles float /on surface move produce hydrogen (may be shown in word or balanced equation) {an alkaline/metal hydroxide} solution (may be shown in word or balanced equation) gets smaller / disappears / dissolves reactivity increases with {increasing atomic number/ down the group} / potassium effervesces more than sodium and lithium / potassium moves faster than sodium or lithium sodium and potassium melt/form a (silver-coloured) ball hydrogen burns when potassium/ sodium react potassium gives a lilac flame/sodium gives a yellow flame Universal Indicator added to water turns blue/purple Explanation (group 1 metals) react by losing one electron electron is more easily lost with {increasing atomic number/ down the group} {electron/ outer shell} is further away from nucleus/ atomic radius increases/ there are more electron shells with {increasing atomic number/ down the group} {more shielding (of outer electron)/ less attraction between nucleus and outer electron/ more shells between outer electron and nucleus} with {increasing atomic number/down the group} Level 0 No rewardable material a limited description of one or two points describing the reactions or explaining them e.g. reactivity increases down the group. the answer communicates ideas using simple language and uses limited scientific terminology. spelling, punctuation and grammar are used with limited accuracy a simple description of at least three points describing the reactions OR a combination of three points from the description and explanation e.g. they all float on water, fizz and potassium gives a lilac flame. the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. spelling, punctuation and grammar are used with some accuracy a detailed description and explanation of at least five points describing the reactions and explaining the pattern of reactivity e.g. the metals all fizz, float and produce hydrogen, the reactivity increases down the group because the outer electron is more easily lost. the answer communicates ideas clearly and coherently and uses scientific terminology accurately. spelling, punctuation and grammar are used with few errors.

8 4(a) 4(b)(i) B potassium and caesium, copper and iron A description linking Any reference to molecules/molecular/intermolecul ar/covalent scores 0 marks overall (regular arrangement of) positive ions /cations metal ions (surrounded by) {delocalised/sea of} electrons reject negative and positive particles / positive atoms / protons ignore descriptions of atoms in rows/ layers of particles etc cloud of electrons ignore free 4(b)(ii) An explanation linking M1 electrons M2 move/flow M2 dep on M1 pass through / travel For M2: ignore free/delocalised (electrons) ignore electricity flows ignore (electrons) vibrate ignore carry/pass the current/charge

9 4(c)(i) A description including any two from moves (around) on the surface floats moves (around) effervescence / fizzing / bubbles white smoke formed ignore gas/hydrogen given off melts/changes to a ball shape becomes smaller /disappears dissolves / explodes Ignore: burns/catches fire/ignites/flame/sparks ignore addition of indicators 4(c)(ii) 2Na + 2H 2 O 2NaOH + H 2 NaHO LHS RHS balancing of correct formulae ignore brackets around OH Use of lower case h, upper case A, lower case o, or use of superscripts or large numbers inside the formulae loses 1 mark only ignore state symbols (3)

10 Group 7 Mark Scheme Level Edexcel Subject Chemistry Exam Board GCSE(9-1) Topic Groups in the Periodic Table Sub Topic Group 7 Booklet Mark Scheme Time Allowed: 65 minutes Score: /54 Percentage: /100

11 Answers Acceptable Answers Mark 1(a)(i) A displacement Answers Acceptable Answers Mark 1(a)(ii) orange Any colour or combination of colours from brown, red, orange and yellow Ignore shade of colours Reject other colours combined with these e.g. yellow-green Answers Acceptable Answers Mark 1(b) C 1(c) (H 2 + Br 2 ) 2HBr Ignore state symbols correct formula for HBr Allow BrH balancing of correct formulae 1(d) [24 + 2x35.5] (= 95) 95 with no working [24 + 2x35.5] with no answer or an incorrect answer scores Answers Acceptable Answers Mark 1(e) relative formula mass =[ ] (= 42) (19/42) x 100 (= 45.2 (%)) (19/[19+23]) x 100 (= 45.2 (%)) [(19/their relative formula mass) x100] (=45.2(%)) consequential on their relative formula mass 45/45.2 (%) with no working Ignore additional significant figures Allow 42 seen in working Allow (19/23) x 100 = {82.6% / 83%}

12 2(a)(i) C cations in a sea of electrons 2(a)(ii) (metals have) high melting point a lot of energy needed to break/overcome (metallic) bonds energy needed to break/overcome strong (metallic) bonds Ignore references to boiling point Reject reference to intermolecular forces/covalent (bonds) /attraction between ions/breaking ionic bonds/ breaking covalent bonds 2(a)(iii) An explanation including two of the following points argon is inert/does not react/is unreactive because it has 8 electrons in its outer shell Ignore argon is in group 0/8 argon is a noble gas Ignore argon does not burn does not {gain/lose/share} electrons has a full outer shell (of electrons) has a stable electron configuration metals would react in/with air/oxygen argon will exclude air from welding point form (metal) oxide prevents oxidation

13 2(b) 2 Fe + 3 Br 2 2 FeBr 3 M1 Correct symbol/formulae M2 balancing of correct symbol/formulae Reject incorrect use of upper/lower case / subscripts for M1 but allow ECF for M2 2(c) C grey solid 2(d) A explanation including For M1 reject reference to reactivity of halide ions eg chlorine more reactive than bromide M1 order of reactivity chlorine > bromine > iodine halogens/they decrease in reactivity down the group/table chlorine is most reactive and iodine is least reactive Ignore reference to displacement of halide ions eg chlorine displaces bromide and M2 one of the following points chlorine displaces bromine (from bromide) AND chlorine displaces iodine (from iodide) bromine displaces iodine (from iodide) AND bromine does not displace chlorine (from chloride) iodine does not displace chlorine(from chloride) AND iodine does not displace bromine (from bromide) Ignore replaces chlorine reacts with bromide AND iodide chlorine takes part in two (displacement) reactions bromine reacts with iodide AND does not react with chloride bromine takes part in one (displacement) reactions iodine does not react with chloride or bromide iodine does not take part in any (displacement) reactions

14 number Answer Mark 3(a) Candidates relate information given to order of elements in the periodic table to predict: dark grey/black and solid/crystals number *3(b) Indicative content Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme. The indicative content below is not prescriptive and candidates are not required to include all the material which is indicated as relevant. Additional content included in the response must be scientific and relevant. AO1 (6 marks) order of reactivity: chlorine > bromine > iodine The order of reactivity supported by suitable experiments from: add (aqueous) chlorine to a solution of potassium bromide the solution turns orange/yellow bromine is produced / Cl 2 + 2KBr Br 2 + 2KCl / Cl 2 + 2Br - Br 2 + 2Cl - (so) chlorine is more reactive than/displaces bromine /oxidises bromide ions add (aqueous) bromine to a solution of potassium iodide the solution turns yellow/red/ brown iodine is produced / Br 2 + 2KI I 2 + 2KBr / Br 2 + 2I - I 2 + 2Br - (so) bromine is more reactive than/displaces iodine/ oxidises iodide ions add (aqueous) chlorine to a solution of potassium iodide the solution turns yellow/red/ brown iodine is produced / Cl 2 + 2KI I 2 + 2KCl / Cl 2 + 2I - I 2 + 2Cl - (so) chlorine is more reactive than/displaces iodine/oxidises iodide ions Mark Allow use of suggested reactions which do not produce a displacement reaction, e.g. add (aqueous) bromine to a solution of a potassium chloride with suitable conclusion/explanation (6)

15 Level Mark Descriptor 0 No rewardable material. Level Demonstrates elements of chemical understanding, some of which is inaccurate. Understanding of scientific ideas, enquiry, techniques and procedures lacks detail. (AO1) Presents an explanation with some structure and coherence. (AO1) Level Demonstrates chemical understanding, which is mostly relevant but may include some inaccuracies. Understanding of scientific ideas, enquiry, techniques and procedures is not fully detailed and/or developed. (AO1) Presents an explanation that has a structure, which is mostly clear, coherent and logical. (AO1) Level Demonstrates accurate and relevant chemical understanding throughout. Understanding of the scientific ideas, enquiry, techniques and procedures is detailed and fully developed. (AO1) Presents an explanation that has a well-developed structure which is clear, coherent and logical. (AO1) number Answer Additional guidance Mark 3(c)(i) calculates mol of Fe calculates mol of Br 2 determines simplest ratio/lhs of equation deduces formula of iron bromide produced/rhs of equation OR divides mass by relative atomic mass simplest ratio empirical formula deduces LHS to obtain balanced equation Example of calculation mol Fe = = mol Br 2 = ( 2 80 ) = 0.15 ratio Fe:Br 2 = 2 : 3/ 2Fe + 3Br 2 2FeBr 3 /Fe 2 Br 6 Fe Br : : : 3 FeBr 3 2Fe + 3Br 2 à 2FeBr 3 (4)

16 number 3(c)(ii) Answer Mark An explanation that combines identification application of knowledge (1 mark) and reasoning/justification application of understanding (1 mark): bromine atoms are reduced because electrons are gained to form bromide ions

17 4(a) Fe Cl Cl 2 Fe 2.8/ / or FeCl 2 with no working (3) 1 2 FeCl 2 Consequential errors: if upside down ie 56 / 2.8 and 35.5 / 3.55 ratio 20 : 10 or 2 : 1 empirical formula Fe 2 Cl allow 3 marks for 2.8 / 56 and 3.55 / 71 ratio 0.05: 0.05 or 1 : 1 empirical formula FeCl 2 allow 2 marks for 2.8 / 56 and 3.55 / 71 ratio 0.05: 0.05 or 1 : 1 empirical formula FeCl allow 2 marks for Fe Cl 2.8/ / (0) Fe 5 Cl - ECF (3)

18 4(b) EITHER 2x23 g Na makes 2x58.5 g NaCl 23.4 g with no working (3) 23.4 g from any method (3) do not accept 23(.0) 9.2 g Na makes (2x58.5)x9.2 g NaCl 46 (= 23.4 g) OR 23 g Na makes 58.5 g NaCl 9.2 g Na makes (58.5)x9.2 g NaCl 23 (= 23.4 g) mark consequentially eg 46 g Na makes (2x ) (0) g NaCl mol Na used = 9.2/23 (= 0.4) mol NaCl = 0.4 mass NaCl = 0.4 x 58.5 Ignore units throughout unless incorrect (= 23.4 g) mark consequentially awarding 2 marks for 46.8 g,11.7 g and 16.3 g (see last example opposite). 9.2 g Na makes (2x )x9.2 g NaCl 46 (= 16.3 g) (3)

19 *4(c) Indicative Content A description, comparison and explanation including some of the following points Order of reactivity: chlorine > bromine > iodine Experiment Mark add (aqueous) chlorine to a solution of potassium bromide the solution turns orange/yellow bromine is produced Conclusion/Explanation and equation: (so) chlorine is more reactive than / displaces bromine Cl 2 + 2KBr Br 2 + 2KCl / Cl 2 + 2Br - Br 2 + 2Cl - Experiment add (aqueous) bromine to a solution of potassium iodide the solution turns brown iodine is produced Conclusion/Explanation and equation: (so) bromine is more reactive than / displaces iodine Br 2 + 2KI I 2 + 2KBr / Br 2 + 2I - I 2 + 2Br - Experiment add (aqueous) chlorine to a solution of potassium iodide the solution turns brown iodine is produced Conclusion/Explanation and equation: (so) chlorine is more reactive than / displaces iodine Cl 2 + 2KI I 2 + 2KCl / Cl 2 + 2I - I 2 + 2Cl - Allow use of organic solvents to identify halogens Allow use of suggested reactions which do not produce a displacement reaction eg add (aqueous) bromine to a solution of a potassium chloride with suitable conclusion/explanation Allow use of table of suggested experiments (6)

20 Level No rewardable content a limited description of at least one experiment in which any halogen solution is added to any halide solution (not of the same halogen) OR describes order of reactivity as Cl > Br > I the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy a simple description of at least two displacement experiments AND EITHER at least one correct explanation/conclusion OR at least one correct observation of a displacement reaction that works/balanced equation. the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a detailed description of at least two displacement experiments AND (a total of) at least two correct explanations/conclusions AND at least one correct observation of a displacement reaction that works/ balanced equation the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors

21 5(a)(i) toxic / poisonous (gas) Ignore other words such as harmful / dangerous / smelly / corrosive 5(a)(ii) A description including the following points (damp blue) litmus (paper) (turns red then) white / bleaches Allow use of any suitable named indicator with correct result eg (damp) universal indicator paper (turns red then) white OR (damp) starch iodide paper (turns) dark blue / black 5(a)(iii) making {poly(chloroethene / PVC / solvents / medicines / agrochemicals / ignore water purification / swimming pools disinfectants} micro-organisms bleach / sterilising water / killing bacteria 5(a)(iv) 2NaCl + 2H 2 O 2NaOH + H 2 + C 2 NaCl + H 2 O NaOH + ½ H 2 + ½ Cl 2 correct products balancing of correct formulae

22 QWC *5(b) Indicative Content A comparison including some of the following points Comparing volumes of hydrogen and oxygen (in each experiment) volume of hydrogen is twice volume of oxygen because water molecules contain twice as many hydrogen atoms as oxygen atoms / is H 2 O overall 2H 2 O 2H 2 + O 2 Mark Relating volumes of gases to current and time (from experiments 1 and 2) time doubles (from experiments 1 and 2) volumes of gases double Volumes of gases are directly proportional to the time for electrolysis / passage of current (from experiments 1 and 3) as current x 1.5 (from experiments 1 and 3) volumes of gases x 1.5 volumes of gases are directly proportional to the current (6) Level 0 No rewardable content a limited description of one trend e.g. increased time gives an increased gas volume the answer communicates ideas using simple language and uses limited scientific terminology spelling, punctuation and grammar are used with limited accuracy a simple description e.g. if the time is doubled, the volume of gas is doubled and if the current is increased the volume of gas increases the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy a detailed description e.g. volume of hydrogen is twice volume of oxygen and as time doubles, volume of gas doubles or as current x 1.5, volume of gas x 1.5 the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors

Answer Acceptable answers Mark

Answer Acceptable answers Mark 1(a) Answer D Mark 1(b) An explanation linking two of the following reaction produces heat/exothermic (sodium) has low melting point (sodium) has low density/density less than water ignore sodium floats