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1. (a) Mass of the isotope compared to 1/12thORmass of the atom compared to 1/12th

(the mass of a) carbon-12 OR 12C (atom) IGNORE Reference to average OR weighted mean(i.e. correct definition of relative atomic mass will score both marks)ALLOW mass of a mole of the isotope/atom with 1/12th the mass of a mole OR 12 g of carbon-12 for two marks.ALLOW 2 marks for:‘Mass of the isotope OR mass of the atom compared to 12C atom given a mass of 12.0’i.e. ‘given a mass of 12’ OR C12 is 12 communicates the same idea as 1/12th.’ALLOW 12C OR C12ALLOW 2 marks for:

1212/1 carbonofmassthofmassisotopetheofmass

i.e. fraction is equivalent to ‘compared to’ALLOW 1 mark for a mix of mass of atom and mass of mole of atoms, i.e. ‘mass of the isotope/mass of an atom compared with 1/12th the mass of a mole OR 12 g of carbon-12.’DO NOT ALLOW mass of ‘ions’ OR mass of element

2

(b) (151 × 47.77) + (153 × 52.23)100

OR

72.1327 + 79.9119OR

152.0446 (calculator value)

Ar = 152.04 ALLOW Correct answer for two marksALLOW One mark for ECF from transcription error in first sum provided final answer is to 2 decimal points and is to between 151 and 153 and is a correct calculation of the transcription

2[4]

Rainham School for Girls 1

2. (i) 153Eu has (2) more neutrons

OR153Eu has 90 neutrons AND 151Eu has 88 neutrons

ALLOW There are a different number of neutronsIGNORE Correct references to protons / electronsDO NOT ALLOW Incorrect references to protons / electrons

1

(ii) (It has the) same number of protons AND electronsORBoth have 63 protons and 63 electrons

ALLOW Same number of protons AND same electron configurationDO NOT ALLOW ‘Same number of protons’ without reference to electrons (and vice versa)

1[2]

3. (i) The H+ ion in an (nitric) acid has been replaced by a metal ionOR by a Ca2+ ion

DO NOT ALLOW it has been produced by the reaction of an acid and a base as this is stated in the question.

IGNORE references to replacement by NH4+ ions or positive

ions.ALLOW H OR Hydrogen for H+;DO NOT ALLOW Hydrogen atomsALLOW Ca OR Calcium for Ca2+.DO NOT ALLOW Calcium atomsALLOW ‘metal’ for ‘metal ion

1

(ii) 2HNO3(aq) + Ca(OH)2(aq) → Ca(NO3) 2 (aq)+ 2H2O(l)Formulae Balance AND states

ALLOW multiplesALLOW (aq) OR (s) for Ca(OH) 2

2


(iii) Accepts a proton OR accepts H+

ALLOW H+ + OH–→ H2OALLOW OH– reacts with H+ OR OH– takes H+

ALLOW OH– ‘attracts’ H+ if ‘to form water’ is seen

DO NOT ALLOW OH– neutralises H+ (‘neutralises’ is in the question)

1[4]

4. (a) (i) Calculate correctly mol102.20

100025.00.0880 3–

OR 0.00220 mol

ALLOW 0.0022 OR 2.2 × 10–3 mol1

(ii) Calculates correctly 200220.0

= 1.10 × 10–3 mol

OR 0.00110 mol

ALLOW 0.0011 OR 1.1 × 10–3 molALLOW ECF for answer (i)/2 as calculator value or correct rounding to 2 significant figures or more but ignore trailing zeroes

1

(iii)3–dmmol0625.0

17.6010000.00110

OR 6.25 × 10–2 mol dm–3

ALLOW 0.063 OR 6.3 × 10–2 mol dm–3

ALLOW ECF for answer (ii) × 1000/17.60ORECF from (i) for answer (i)/2 × 1000/17.60 as calculator value or correct rounding to 2 significant figures or more but ignore trailing zeroes

1

(b) (i) (The number of) Water(s) of crystallisation IGNORE hydrated OR hydrous

1


(ii) 142.1 ALLOW 142ALLOW Mr expressed as a sumALLOW ECF from incorrect Mr and x is calculated correctly

x = 0.18)1.1421.322(

= 10 ALLOW ECF values of x from nearest whole number to calculator valueALLOW 2 marks if final answer is 10 without any working

2[6]

5. (i) O goes from –2 to 0 Oxidation numbers may be seen with equation

N goes from +5 to +4

N is reduced AND O is oxidised Third mark is dependent upon seeing a reduction in oxidation number of N and an increase in oxidation number of OALLOW ECF for third mark for N is oxidised and O is reduced if incorrect oxidation numbers support thisIGNORE references to strontiumIGNORE references to electron loss OR gainDO NOT ALLOW ‘One increases and one decreases’

3


(ii) Calculates correctly:

Mol of Sr(NO3)2 = 0250.0

6.21129.5

ALLOW 0.025

Calculates correctly:Mol of gas = 5/2 × 0.0250 = 0.0625

ALLOW ECF for first answer × 2.5 as calculator value or correct rounding to 2 significant figures or more but ignore trailing zeroes

Calculates correctly:Volume of gas = 24.0 × 0.0625 = 1.50 dm3

ALLOW ECF for second answer × 24(.0) as calculator value or correct rounding to 2 significant figures or more but ignore trailing zeroesDO NOT ALLOW ECF of first answer × 24(.0) (which gives 0.6(0) dm3) as this has not measured the volume of any gas, simply 0.0250 mol of solid Sr(NO3)2 converted into a gasi.e. This answer would give one mark

ALLOW 1.5 dm3

ALLOW ECF producing correct volume of NO2 onlyi.e. 1.2(0) dm3 would give two marksORALLOW ECF producing correct volume of O2 onlyi.e. 0.3(0) dm3 would give two marks

3[6]

6. (i) (atoms of the) same element OR same atomic no.OR no. of protons

AND

with different numbers of neutrons OR different masses IGNORE ‘same number of electrons’DO NOT ALLOW ‘different numbers of electrons’DO NOT ALLOW ‘different relative atomic masses’DO NOT ALLOW ‘elements with different numbers ofneutrons’ without mention of same protons OR sameatomic number

1


(ii) same (number of) electrons (in the outer shell)

OR

same electron configuration OR structure DO NOT ALLOW different number of protonsIGNORE ‘same number of protons’IGNORE ‘they are both carbon’ OR ‘they are both thesame element’

1

(iii) mass of the isotope compared to 1/12thORmass of the atom compared to 1/12th

(the mass of a) carbon-12 OR 12C (atom) IGNORE reference to average OR weighted mean(i.e. correct definition of relative atomic mass will score bothmarks)ALLOW mass of a mole of the isotope/atom with 1/12th themass of a mole OR 12 g of carbon –12 ALLOW 2 marks for:‘mass of the isotope OR mass of the atom compared to 12C atom given a mass of 12.0’i.e. ‘given a mass of 12’ communicates the same idea as 1/12th.’ ALLOW 12C OR C12ALLOW FOR 2 MARKS:

12carbonofmass1/12thofmassisotopetheofmass

i.e. fraction is equivalent to ‘compared to’ALLOW 1 MARK FOR a mix of mass of atom and massof mole of atoms, i.e.:‘mass of the isotope/mass of an atom compared with1/12th the mass of a mole OR 12 g of carbon –12.’

2

[4]


7. giant covalent (lattice)

layers

Each of the three properties below must be linked toexplanationgood conductor – because it has mobile electrons ORdelocalised electrons OR electrons can move

high melting / boiling point – because strong ORcovalent bonds have to be broken

soft – because there are van der Waals’ forces ORintermolecular forces OR weak bonds OR weak forcesbetween the layers

ORsoft – because layers can slide

Use annotations with ticks, crosses etc. for this part.All five marking points are independentALLOW giant atomic OR giant molecular ORmacromolecularALLOW planes OR sheetsAllow diagram showing at least two layersElectron(s) must be spelt correctly ONCEDO NOT ALLOW ‘strong ionic bonds’ OR strong metallicbonds.

[5]

8. (i) 0.0268 OR 0.027 OR 0.02675 mol NO OTHER ACCEPTABLE ANSWER

1

(ii) 1.61 × 1022

ALLOW 1.6 × 1022 up to calculator valueALLOWECF answer to (i) × 6.02 × 1023

ALLOW any value for NA in the range:

6.0 × 1023 – 6.1 × 1023

1

[2]



OR

soft – because layers can slide 9. (i)2NH3 + H2SO4 → (NH4)2SO4

ALLOW 2NH4OH + H2SO4 → (NH4)2SO4 + 2H2O

ALLOW NH3 + H+ → NH4+

ALLOW any correct multipleIGNORE state symbols

1

(ii) when the H+ in an acid is replaced by a metal ion OR anammonium ion OR a + ion

ALLOW H for H+;ALLOW ‘metal’ for ‘metal ion’i.e.: H in an acid can be replaced by a metal

1

(iii) accepts a proton OR accepts H+ ALLOW donates a lone pairALLOW removes H+

ALLOW forms OH− ions1

(iv) 132.1 IGNORE unitsNO OTHER ACCEPTABLE ANSWER

1

[4]

10. (a) (i) white precipitate OR white solid DO NOT ALLOW goes white / cloudy / milky / off-whiteDO NOT ALLOW creamy white precipitateALLOW milky white precipitate

1


(ii) Ag+(aq) + Cl–(aq) → AgCl(s)

Balanced equation correct

ALL state symbols correct ALLOW 2 marksAgNO3(aq) + Cl–(aq) → AgCl(s) + NO3

–(aq)(equation mark and state symbol mark)ALLOW 1 mark for:AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)(state symbol mark)ALLOW 1 mark for the state symbols for THESEbalanced equation ONLY:Ag2+(aq) + 2Cl–(aq) → AgCl2(s)Ag(aq) + Cl(aq) → AgCl(s)

2

(iii) (precipitate) dissolves OR disappears OR goescolourless OR goes clear

ALLOW forms a solution1

(b) (i) removes or kills bacteria OR kills germs ORkills micro-organisms OR make it safe to drink ORsterilises water

ALLOW to make water potableIGNORE virusDO NOT ALLOW ‘purifies water’DO NOT ALLOW ‘antiseptic’

1

(ii) it is toxic OR poisonous OR could form chlorinatedhydrocarbons

ALLOW forms carcinogens OR forms toxinsDO NOT ALLOW harmfulDO NOT ALLOW ‘it causes cancer’(chlorine is not a carcinogen)DO NOT ALLOW ‘irritates lungs’

1


(c) (i) Cl2 is 0 AND HCl is –1 AND HClO is (+)1 ALLOW 1–ALLOW 1+

1

(ii) It has been both oxidised and reducedORIts oxidation state has increased and decreased

it has been oxidised (from 0) to +1 ANDit has been reduced (from 0) to –1 (These two points together subsume the first markingpoint)

ALLOW ‘chlorine’ OR ‘it’DO NOT ALLOW chlorIDEIF CORRECT OXIDATION STATES IN (i), ALLOW 2marks for:it is oxidised to form HClOit is reduced to form HCl

2

(iii) Cl2 + 2NaOH → NaClO + NaCl + H2O IGNORE state symbols

1

(d) (i) 2ClO2 → Cl2 + 2O2ORClO2 → ½Cl2 + O2

IGNORE state symbols1

(ii) divides each % by correct Ar:

i.e. 0.168.56:

5.350.42:

0.120.1

OR1.20, 1.18, 3.55

HClO3ALLOW 1 mark for empirical formula of HCl2O6(use of atomic numbers)ALLOW 1 mark for empirical formula of H3Cl3O(upside-down expression)ALLOW ECF for use of incorrect Ar values to getempirical formula but only if no over-roundingALLOW 2 marks for correct answer of HClO3

2


(iii) the oxidation number of chlorine ALLOW ‘the oxidation state of chlorine ORoxidation number of chlorine is 5’DO NOT ALLOW ‘it’ instead of ‘chlorine’DO NOT ALLOW ‘the oxidation state OR number ofchlorIDE is 5’

1

[14]

11. (a) BaO Ba3N2

Treat any shown charges as working and ignore.Treat B for Ba as a slip

2

(b) (i) 3.13711.0

mark is for the working out which MUST lead to the correct answer of 8 × 10–4 up to calculator value

1

(ii) 19.2ORcalculated answer to (b)(i) × 24000

ALLOW 19 up to calculator value.1

(iii) 8.0 × 10–3

ORcalculated answer to (b)(i) × 10

ALLOW 8.01 × 10–3 up to calculator value1

(iv) any pH > 7 but <15 ALLOW a correct range of pH.

1


(c) Less barium to react ORsome barium has already reacted

ALLOW less volume because contains some BaO or Ba3N2

1

(d) reactivity increases (down the group)

atomic radii increase ORthere are more shells

there is more shielding OR more screening

the nuclear attraction decreases ORIncreased shielding and distance outweigh theincreased nuclear charge

easier to remove (outer) electrons ORionisation energy decreases

USE annotations with ticks, crosses, ecf, etc forthis part.DO NOT ALLOW more orbitals OR more sub-shells‘More’ is essentialALLOW ‘more electron repulsion from inner shells’ALLOW ‘nuclear pull’IGNORE any reference to ‘effective nuclear charge’ALLOW easier to form positive ion

5

[12]

12. (i)

protons neutrons electrons24Mg 12 12 12

25Mg 12 13 12

24Mg line correct 25Mg line correct

mark by row2


(ii) 10011.292610.112578.6024

OR 18.8640 + 2.5275 + 2.9354

OR 24.3269

Ar = 24.33 (to 4 sig figs) ALLOW two marks for Ar = 24.33 with no working outALLOW one mark for ecf from incorrect sum provided final answer is between 24 and 26 and is to 4 significant figures, e.g. 24.3235 gives ecf of 24.32

2

(iii) The (weighted) mean mass of an atomOR (weighted) average mass of an atom

relative to 1/12th (the mass)

of (one atom of) 12C ALLOW The (weighted) mean massOR (weighted) average mass of an atomOR average atomic mass compared with (the mass of) carbon-12 which is 12 For 1st marking point, ALLOW mean mass of the isotopesOR average mass of the isotopesDo NOT ALLOW the singular: isotopeALLOW mass of one mole of atoms compared to 1/12th (the mass) of one mole / 12 g of carbon-12

mass of one mole of atoms

1/12th the mass of one mole / 12 g of carbon-12 3

[7]

13. (i) Mg oxidation number changes from 0 to (+)2OR oxidation number increases by 2

ALLOW correct oxidation numbers shown in equation2nd mark is dependent on identification of MgIGNORE electrons

2


(ii) Mg/solid dissolves OR Mg/solid disappearsOR (Mg/solid) forms a solution

bubbles OR fizzes OR effervesces OR gas produced IGNORE metal reactsIGNORE temperature changeIGNORE steam producedDO NOT ALLOW carbon dioxide gas producedDO NOT ALLOW hydrogen produced without gas

2

[4]

14. (i) M(MgSO4) = 120.4 OR 120 (g mol–1)

mol MgSO4 = 120.41.51

= 0.0125 mol ALLOW 0.013 up to calculator value of 0.012541528 correctly rounded (from M = 120.4 g mol–1)ALLOW 0.013 up to calculator value of 0.012583333 correctly rounded (from M = 120 g mol–1)ALLOW ecf from incorrect M i.e. 1.51 ÷ M

2

(ii) 18.01.57

= 0.0872(2) (mol) ALLOW 0.09 up to calculator value of 0.08722222

1

(iii) × = 7 ALLOW ecf i.e. answer to (ii) ÷ answer to (i)ALLOW correctly calculated answer from 1 significant figure up to calculator value, ie, × does not have to be a whole number. Likely response = 6.95

1

[4]


15. (i) mol HCl = 1.50 × 10–2

volume HCl(aq) = 75.0 ALLOW answers to 2 significant figuresALLOW ecf from wrong number of moles

i.e 0.2001000HCIofmoles

ALLOW one mark for 37.5 (from incorrect 1:1 ratio)2

(ii) 180 No other acceptable answer

1

[3]

16. (i) Ca(OH)2 IGNORE charges, even if wrong

1

(ii) Ca(NO3)2 IGNORE charges, even if wrong

1

[2]

17. (i) atoms of the same element with different numbers ofneutrons/different masses (1) 1

(ii) 79Br 35 protons, 44 neutrons, 35 electrons (1)81Br 35 protons, 46 neutrons, 35 electrons (1) 2

(iii) (1s2)2s22p63s23p63d104s24p5 (1) 1[4]


18. (i) Molar mass of CaCO3 = 100.1 g mol–1 (1)2.68/100.1 = 0.0268/0.027 (1) 2

(ii) 0.0268 mol × 24,000 = 643 cm3 (1) 1

(iii) moles HNO3 = 2 × 0.0268= 0.0536 /0.054 mol (1)(i.e. answer to (i) × 2)

volume of HNO3 = 0.0536 × 1000/2.50 = 21.4 cm3 (1) 2[5]

19. Molar mass of anhydrous calcium nitrate = 164.1 g mol–1 (1)Ratio Ca(NO3)2 : H2O = 69.50/164.1 : 30.50/18or 0.4235 : 1.694 or 1 : 4 (1)Formula = Ca(NO3)2•4H2O (1)

[3]

20. (i) because Ca has changed from 0 to +2 (1)and H has changed from +1 to 0 (1) 2

(ii) Calcium reacts with water producinghydrogen/H2/calcium/hydroxide/Ca(OH)2 (1) (i.e. one product)Ca(s) + H2O(l) Ca(OH)2(aq) + H2(g) (1) (i.e. full equation)Equation would subsume both two marks 2

[4]

21. (a) (atoms of) same element/same atomic number….. with

different numbers of neutrons/different masses 1

(b) 3

isotope percentagecomposition

number of

protons neutrons electrons85Rb 71 to 73 37 48 37

87Rb 27 to 29 37 50 37

mark must addup to 100

ie 1 mark for each atomic structure; 1 for compositions.

56.85/100

28) (87 72) (85 rA


= 85.6 2nd mark for significant figures 2

71/29: 85.58 = 85.6

73/27: 85.54 = 85.5

(c) carbon-12/12C 1[7]

22. (i) Simplest (whole number) ratio of atoms/moles/elements 1

(ii) ratio Rb : Ag : I = 7.42/85.5 : 37.48/108 : 55.10/127

or 0.0868 : 0.347 : 0.434

or 1 : 4 : 5

= RbAg4I5 2[3]

23. (a) (i) 12 50/1000 = 0.600 mol 1

(ii) 4 mol HCl 1 mol Cl2 / moles Cl2 = 0.15 mol vol of Cl2 = 0.15 24 = 3.60 dm3 2

2nd mark is consequential on molar ratio given

(b) Evidence that the oxidation number of Mn has reducedand one of the oxidation numbers correct (ie MnO2: ox noof Mn = 4 or MnCl2: ox no of Mn = 2 The other oxidation number of Mn is correct,ie in MnO2: ox no of Mn = 4or in MnCl2: ox no of Mn = 2 2

[5]


24. (i) mass = 0.0500 23.0 = 1.15 g 1

(ii) moles H2 = 0.0250 volume H2 = 0.0250 24 = 0.600 dm3 2ecf from calculated moles H2

0.0500 mol in 50.0 cm3 1

(iii) concentration = 0.0500 20 = 1.00 mol dm−3 [4]

25. (i) 2Na O2 Na2O2 1

(ii) Na2O2 2H2O H2O2 2NaOH 1

correct covalent bonds shown (iii) electron count (14) for rest of molecule correct 2

[4]

26. (i) loss (of electrons) 1

(ii) Ba 0 ()2 (accept 2) 2

[3]

27. M(BaO) = 137 16 = 153 moles BaO = 500/153 or 3.268 mol moles Ba = 3.268/2 or 1.634 mass Ba formed = 1.634 137 = 224 g

accept 223.856209/223.86/223.9 g.if 6 mol BaO forms 3 mol Ba, award 3rd mark

Alternative methodmass 6BaO=918 g mass 3Ba = 411 g 1g BaO forms 411/918 g Ba 500 g BaO forms 223.856209/223.86/223.9 g Ba

[4]


28. (i)

io n isa tio n

d eflec tio n

to th e p u m pac ce le ra tin g

d e te c tio n

......

.. .. .... .. ....... .. .... ..

protons neutrons electrons25Mg 12 13 1226Mg 12 14 12 2

(ii) 1s22s22p63s2

24 78.60/100 25 10.11/100 26 11.29/100 1

(iii) = 24.33 (calc value: 24.3269. This scores one mark)24.32 with no working, award 1 mark only.24.3 with no working, no marks (Periodic Table value) 2

[5]

29. (i) Oxidation state goes from 0 in O2 2 in MgO 2

(ii)

M g

2+ 2–

or with Mg full shell.correct dot and cross ; correct charges 2

[4]

30. (i) MgO has reacted with CO2 1

(ii) Solid dissolves / disappearsFizzing / bubbles 2MgO 2HCl MgCl2 H2OMgCO3 2HCl MgCl2 CO2 H2Oboth reactions form magnesium chloride/MgCl2 3

[6]


31. (i) ratio N : H : S : O = 1412.24

: 194.6

: 1.3261.27

: 1633.41

:

= 2 : 8 : 1 : 3

Empirical formula = N2H8SO3N2H4SO3 is worth 1 mark from consistent use of at nos. 2

(ii) H2O 2NH3 SO2 (NH4)2SO3 1(Award mark for N2H8SO3)

[3]

32. (a) (i) Amount of substance that has the same number ofparticles as there are atoms in 12 g of 12C/6 1023/ Avogadro’s Number 1

(ii) moles = 1000120275.0

= 0.0330 mol

moles Cl2 = 20330.0

= 0.0165 mol 1(iii) volume Cl2 = 0.0165 24000 = 396 cm3 / 0.396 dm3

792 cm3 worth 1 mark (no molar ratio)1584 cm3 worth 1 mark (x 2)units needed. 2

(iv) bleach / disinfectant /sterilising /killing germs 1

(b) NaClO3 1[6]

33. (i) CaCO3 (s) 2HCl(aq) CaCl2(aq) CO2(g) H2O (l)

CaO(s) 2HCl(aq) CaCl2(aq) H2O (l)

each balanced equation 1 mark (2)

all state symbols (1) 3

(ii) CaCO3 fizzes/ gas given off/ gas evolved / carbon dioxide evolved (1) 1[4]


34. (i) (atoms of) same element/same atomic number/number of protons withdifferent numbers of neutrons/diff masses 1

(ii)

proton neutron electron

relative mass 1 1 18401

/ negligible

relative charge 1 0 −1i.e. 1 mark for each correct rowfor electron, accept 1/1500 – 1/2000for charges, accept ; 0; –

2[3]

35. (i) average atomic mass/weighted mean/average mass

compared with carbon-12

1/12th of mass of carbon-12/on a scale where carbon-12 is 12 OR

(ii) The mass of 1 mole of atoms of an element

compared with 12 g of carbon-12 3

Ar = 10042.79) (123 57.21) (121

/ 121.8558

= 121.9 2[5]


36. (i) Mass Sb2S3 in stibnite = 5% of 500 kg = 25.0 kg

Moles Sb2S3 = 340100.25 3

/ 73.5/ 73.529 /73.53/ 74 mol

(calculator value: 73.52941176)

If 5% is not used, 1471 mol; ecf for 2nd mark

(calculator value: 1470.588235)

If 5% is used 2nd, 73.6 mol: OK for both marks 2

(ii) moles Sb = 2 73.5 mol

mass Sb = 2 73.5 122 g = 17.9 kg

If the 2 isn’t used, answer = 73.5 122 = 8.95 ecf ans from (i) x 2ecf ans above x 2

OR

% Sb = 244/340 = 71.7%

mass Sb = 25.0 71.7/100 = 17.9 kg (ecf as above) 2[4]

37. (i) Molar mass CaO = 56.1 (g mol–1) (anywhere) 2

moles CaO = 1.5650.1

= = 0.0267/0.027 calc: 0.0267379

Allow 56 which gives 0.0268

(ii) moles HNO3 = 2 0.0267

= 0.0534 or 0.0535 /0.053 mol

(i.e. answer to (i) x 2)

volume of HNO3 = 2.501000 5)(or 0.0534

= 21.4 cm3 2

calc from value above = 21.3903743

If 0.053 mol, answer is 21 cm3 but accept 21.2 cm3

If 0.054 mol, answer is 22 cm3 but accept 21.6 cm3

[4]


38. (i) dative covalent, bonded pair comes from same atom/ 1electron pair is donated from one atom/both electrons are from the same atom

(ii) Ca(NO3)2 CaO 2NO2 ½O2 or double equation with 2/2/4/1 1

[2]

39. (i) 203.3 g mol−1 1Accept 203

(ii) white precipitate / goes white 1

(iii) Ag+(aq) Cl−(aq) AgCl(s)equation state symbols 2AgCl dissolves in NH3(aq)

(iv) AgBr dissolves in conc NH3(aq)/partially soluble in NH3(aq)

AgI insoluble in NH3(aq) 3[7]

40. (i) a proton donor 1

(ii) MgO 2HCl MgCl2 H2O 1[2]

41.

isotope protons neutrons electrons12C 6 6 6

13C 6 7 6

[2]


42. (i) mass spectrometry 1

(ii) mass of an isotope compared with carbon-12 1/12th of mass of carbon-12/on a scale where carbon-12 is12 2

mass of 1 mole of the isotope/mass of 1 mole of carbon-12is equivalent to the first mark“mass of the isotope that contains the same number ofatoms as are in 1 mole of carbon-12” 1 mark (marklost because of mass units)

(iii) 12 95/100 13 5/100 OR 12.05 = 12.1 (mark for significant figures) (12.1 scores both marks) 2

[5]

43. (i) moles CO2 = 1000 /44 mol = 22.7 mol volume CO2 in 2000 = 22.7 24 = 545 dm3

(ii) reduction = 545 60/100 = 327 dm3 [3]

44. (a) ……Ca(s) …..2 HCl(aq) …….CaCl2(aq) .H2(g). 2

(g) not required for H2

(b) In Ca, oxidation state = 0 and 2In CaCl2, oxidation state = 2 Oxidation number increases from Ca to CaCl2

[4]


45. (i) moles HCl = 2.0 50/1000 = 0.10 1

(ii) moles Ca = ½ moles HCl = 0.050 mass Ca = 40.1 0.050 = 2.00 g / 2.005 g 2(accept 40 0.050 = 2.0 g)(mass Ca of 4.0 g would score 1 mark as ‘ecf’ as molar ratiohas not been identified)

(iii) Ca has reacted with water Ca 2H2O Ca(OH)2 H2

state symbols not required

1st mark for H2 32nd mark is for the rest of the balanced equation

[6]

46. (a) (i) atoms of same element/same atomic number….. withdifferent numbers of neutrons/different masses 1

(ii) isotope protons neutrons electrons 246Ti 22 24 22 47Ti 22 25 22

(b)724.47/

10081.3) (48 9.8) (47 8.9) (46

rA

= 47.7 2[5]

47. (i) moles Ti 1.44/47.9 0.0301 mol/0.03 mol 1(accept use of answer from (b))

(ii) mass of Cl 5.70-1.44 4.26 g moles Cl 4.26/35.5 0.120 mol 25.70/35.5 0.161 mol gets 1 mark

(iii) Ti:Cl 0.0301 : 0.12 1:4.Empirical formula TiCl4 0.0301 : 0.161 mol gives TiCl5 for 1 mark 1

(iv) Ti 2Cl2 TiCl4 1(ecf possible from (iii)covalent

[5]

48. (a) RaCl2 1

(b) Reduction is gain of electrons/decrease in oxidation number


Ra2+ gains 2 electrons Ra/Oxidation state goes from 2 in RaCl2 0 in Ra 2

[3]

49. (a) …Mg(OH)2(s) 2…HCl(aq) ….MgCl2(aq) 2…H2O(l) 1

(b) (i) moles HCl 0.108 500/1000 0.054 1

(ii) moles Mg(OH)2 ½ moles HCl 0.027 molar mass of Mg(OH)2 24.3 17 × 2 58.3 (do not penalise 24)

mass Mg(OH)2 = 58.3 0.027 = 1.57 g / 1.5741 g (accept ans from (ii) 0.027 = 1.566 g)(mass Mg(OH)2 of 3.15 g would score 2 marks as ‘ecf’ as 3molar ratio has not been identified)

(iii) Too much if 2.42 g (dose) ans to (ii) (If answer to (ii) 2.42 g then ‘correct’ response here would 1be ‘Not enough’

[6]

50. CaCO3 reacts with (or neutralises) HCl (or CaCO3 HCl in an equation)

CaCO3 2HCl CaCl2 H2O CO2 (correct equation would score both marks)

[2]

51. (i) as a base (1) ………. accepts a proton/H/ neutralises an acid/reacts with acid to form salt/ has a lone pair of electrons (1) 2

(ii) fertiliser (1) 1

(iii) manufacture of explosives/ dyes/ nitric acid/ fibres/ ammoniumnitrate/ urea/ refrigeration/ cleaning agents/ fertiliser(if not allowed in (ii) (1) 1

[4]


52. (i) 79Br has two less neutrons than 81Br 2

(ii) 79Br have same numbers of protons and same number of electrons 2

[4]

53. (i) Number AND type of atoms (making up a 1molecule)/number of atoms of each element

Not ratio

(ii) P4 6 Br2 4 PBr3 1

(iii) ratio P : Br = 16.2/31 : 83.8/79.9/= 0.52 : 1.05/= 1 : 2 Empirical formula = PBr2 Correct compound = P2Br4 /phosphorus(II) bromide but 3not PBr2

[5]

54. (i) fizzing/gas/hydrogen evolved or Mg dissolves/disappears 1[an incorrect observation negates this mark]

(ii) 2HCl Mg MgCl2 H2

[correct formula for MgCl2. Allow equation with HI/MgI2 instead of HCl]

[balancing: e.g. 2HCl 2Mg 2MgCl H2 will get this mark butnot the 1st] 2

[3]

55. isotope protons neutrons electronsnickel-58 28 30 28nickel-60 28 32 28nickel-62 28 34 28

For ecf, 3rd column same as first column.[3]


56. (i) mass spectrometry mass spec… /mass spectrometer should also be credited 1

(ii) average mass/weighted mean mass of an atom compared with carbon-12 1/12th of mass of carbon-12/on a scale where carbon-12 is 12 mass of 1 mole of atoms (of an element) mass of 1 mole of 3carbon-12 is equivalent to first two marks“mass of the element that contains the same number ofatoms as are in 1 mole of carbon-12” 2 marks (mark lostbecause of mass units)

(iii) 63.0 77.2/100 65.0 22.8/100 / 63.456 2

= 63.5 (mark for significant figures)

(iv) copper/ Cu 1[7]

57. (i) mass of Ni = 2.0g moles of Ni = 2.0/58.7 mol = 0.0341/0.034 mol (1 mark would typically result from no use of 25% 0.136 mol) 22nd mark is for the mass of Ni divided by 58.7

(ii) number of atoms of Ni = 6.02 1023 0.0341 1

= 2.05 1022 / 2.1 1022 atoms

Can be rounded down to 2.1 or 2.0 or 2 (if 2.0)

From 8 g, ans = 8.18/8.2 1022

(and other consequential responses)[3]

58. No mark scheme available

59. No mark scheme available

60. Xe has a bigger atomic radius OR Xe has more shells ALLOW Xe has more energy levelsALLOW Xe has electrons in higher energy level


ALLOW Xe has electrons further from nucleusIGNORE Xe has more orbitals OR more sub-shellsDO NOT ALLOW ‘different shell’ or ‘new shell’

Xe has more shielding

ALLOW More screeningThere must be a clear comparison ie more shielding OR increased shielding.i.e. DO NOT ALLOW Xe ‘has shielding’ALLOW Xe has more electron repulsion from inner shells

The nuclear attraction decreasesOR Outermost electrons of Xe experience less attraction (to nucleus)OR Increased shielding / distance outweighs the increased nuclear charge ORA throughout

ALLOW Xe has less nuclear pullIGNORE Xe has less effective nuclear chargeDO NOT ALLOW nuclear charge for nuclear attraction

[3]

61. (i) (Electrostatic) attraction between oppositely charged ions. IGNORE forceIGNORE references to transfer of electronsMUST be ions, not particles

1

(ii) Mg shown with either 8 of 0 electronsANDS shown with 8 electrons with 2 crosses and 6 dots (or vice versa)

Correct charges on both ions

M g S

2-2+

Mark charges on ions and electrons independentlyFor first mark, if 8 electrons are shown around the Mg then ‘extra electrons’ around S must match the symbol chosen for electrons around Mg Shell circles not requiredIGNORE inner shell electronsBrackets are not required

2[3]

62. (i) Electron pairs in covalent bonds shown correctly using dots andcrosses in a molecule of the F2O

Lone pairs correct on O and both F atoms


F F

O

Must be ‘dot-and-cross’circles for outer shells NOT neededIGNORE inner shellsNon-bonding electrons of O do not need to be shown as pairsNon-bonding electrons of F do not need to be shown as pairs

2

(ii) Predicted bond angle 104 – 105°. ALLOW 103 – 105° (103° is the actual bond angle)

There are 2 bonded pairs and 2 lone pairs Lone pairs repel more than bonded pairs

ALLOW responses equivalent to second marking point. e.g. There are 4 pairs of electrons and 2 of these are lone pairsALLOW ‘bonds’ for ‘bonded pairs’DO NOT ALLOW ‘atoms repel’DO NOT ALLOW electrons repelALLOW LP for ‘lone pair’ALLOW BP for bonded pairALLOW LP repel more if bonded pairs have already been mentioned

3[5]


63. (i) (At least) two NH3 molecules with correct dipole shown with atleast one H with δ+ and one N with δ–

DO NOT ALLOW first mark for ammonia molecules with incorrect lone pairsDO NOT ALLOW first mark if H2O, NH2 or NH is shown

(Only) one hydrogen bond from N atom on one molecule to aH atom on another molecule

ALLOW hydrogen bond need not be labelled as long as it clear the bond type is different from the covalent N–H bondALLOW a line (i.e. looks like a covalent bond) as long as it is labelled ‘hydrogen bond)

Lone pair shown on the N atom and hydrogen bond must hitthe lone pair H y d ro g e n b o n d

HH H

HH H

N

N

δ-δ +

δ-

δ+ δ+

δ+δ+ δ+

ALLOW 2-D diagramsALLOW two marks if water molecules are used. One awarded for a correct hydrogen bond and one for the involvement of lone pair

3

(ii) Liquid H2O is denser than solid In solid state H2O molecules are held apart by hydrogen bondsOR ice has an open lattice

ORAALLOW ice floats for first mark

ORH2O has a relatively high boiling point OR melting point

ALLOW higher melting OR boiling point than expectedDO NOT ALLOW H2O has a high melting / boiling point

(relatively strong) hydrogen bonds need to be brokenOR a lot of energy is needed to overcome hydrogen bondsOR hydrogen bonds are strong

ALLOW other properties caused by hydrogen bonding not mentioned within the specificationE.g. high surface tension – strong hydrogen bonds on the surface

2[5]


64. 3d10 4s2 4p5

ALLOW 4s2 3d10 4p5

ALLOW subscripts or 3D10

ALLOW answers with 1s2 2s2 2p6 3s2 3p6 appearing twice[1]

65. Mg has a giant structure Metallic OR delocalised seen spelt correctly at least ONCE

Mg has metallic bonding OR description of metallic bonding as positive ionsand delocalised electrons

(There is electrostatic attraction between) positive ions and electrons DO NOT ALLOW as label nuclei OR protons for positive ionsALLOW labelled diagram of metallic bonding for second and third marks

2+2+ 2+ 2+2+ 2+ 2+

2+ 2+ 2+

2+2+2+

M g

p o s itiv e io n s

d e lo c a lise d e le c tro n s

Lattice must have at least two rows of positive ions. If a Mg ion is shown it must correct chargeALLOW for labels: + ions, positive ions, cationsDO NOT ALLOW as label nuclei OR protons for positive ions

ALLOW e– or e as label for electronDO NOT ALLOW ‘–’ without label for electron

Cl has a simple molecular OR simple covalent (lattice) Covalent OR molecule OR molecular seen spelt correctly at least ONCEALLOW Cl is a (covalent) molecule


Cl has van der Waals’ forces (between molecules)ORCl has instantaneous dipole–induced dipolesORtemporary dipole–temporary dipole

IGNORE Cl has intermolecular bonding

van der Waals’ forces are weak and metallic bonds are strongORvan der Waals’ forces are weaker than metallic bondsORLess energy is needed to overcome van der Waals’ than metallic bonds

ALLOW ECF from incorrect descriptions of giant structure with strong bonds; e.g. Mg has giant ionic structureALLOW ECF from any incorrect intermolecular forcese.g. permanent dipole–dipole from marking point 5ALLOW vdW easier to breakORA

[6]

66. giant covalent (lattice)

layers

Each of the three properties below must be linked toexplanationgood conductor – because it has mobile electrons ORdelocalised electrons OR electrons can move

high melting / boiling point – because strong ORcovalent bonds have to be broken


ORsoft – because layers can slide

Use annotations with ticks, crosses etc. for this part.All five marking points are independentALLOW giant atomic OR giant molecular ORmacromolecularALLOW planes OR sheetsAllow diagram showing at least two layersElectron(s) must be spelt correctly ONCEDO NOT ALLOW ‘strong ionic bonds’ OR strong metallicbonds.

[5]

67. (i) a shared pair of electrons ALLOW any response that communicates electron pair


ALLOW shared pairs1

(ii)

H

H

HN

Must be ‘dot-and-cross’circles for outer shells NOT neededIGNORE inner shellsNon-bonding electrons of N do not need to be shown asa pair

1

(iii) Shape: pyramidal OR (trigonal) pyramid

Explanation:There are 3 bonded pairs and 1 lone pair Lone pairs repel more than bonded pairs

ALLOW ‘bonds’ for ‘bonded pairs’DO NOT ALLOW ‘atoms repel’DO NOT ALLOW electrons repelALLOW LP for ‘lone pair’ALLOW BP for bonded pair

3

[5]

68. (i) 1s22s22p63s23p6 ALLOW subscripts

1


(ii)

H

N HH

H+

‘Dot-and-cross’ diagram to show four shared pairs ofelectrons one of which is a dative covalent bond (whichmust consist of the same symbols)

IGNORE inner shellsIGNORE ‘+’ sign BUT DO NOT ALLOW a ‘−’ sign.Brackets and circles not required

1

(iii) tetrahedral

109.5° ALLOW 109 – 110°

2

(iv) ions OR electrons cannot move in a solid

ions can move OR are mobile in solution ALLOW ions can move in liquidDO NOT ALLOW ions can move when moltenALLOW 1 mark for:‘Ions can only move in solution’

2

[6]


69.

regular arrangement of labelled + ions with some attemptto show electrons

scattering of labelled electrons between other speciesORa statement anywhere of delocalised electrons (can be intext below)

metallic bond as (electrostatic) attraction between theelectrons and the positive ions

Lattice must have at least 2 rows of positive ionsIf a metal ion is shown (e.g. Na+), it must have the correct chargeALLOW for labels: + ions, positive ions, cationsIf ‘+’ is unlabelled in diagram, award the label for ‘+’ from a statement of ‘positive ions’ in text belowDO NOT ALLOW as label or text positive atom OR protons OR nuclei

ALLOW e– OR e as label for electronDO NOT ALLOW ‘–’ as label for electron

[3]

70. (i) 4 Na + O2 → 2 Na2O

OR 2 Na + ½ O2 → Na2O ALLOW correct multiples including fractionsIGNORE state symbols

1

(ii) (electrostatic) attraction between oppositely charged ions1


(iii)

N a

N a

O+

+2 –

Na shown with either 8 or 0 electronsANDO shown with 8 electrons with 6 crosses and 2 dots (orvice versa) Correct charges on both ions

For 1st mark, if 8 electrons shown around cation then‘extra’ electron(s) around anion must match symbolchosen for electrons in cationShell circles not requiredIGNORE inner shell electrons

ALLOW: 2[Na+] 2[Na]+ [Na+]2 (brackets not required)DO NOT ALLOW [Na2]2+ / [Na2]+ / [2Na]2+

DO NOT ALLOW: [Na2]2+ [Na2]+ [2Na]2+ [Na]2+

2

[4]

71. sodium is a (good) conductor because it has mobileelectrons OR delocalised electronsOR electrons can move

sodium oxide does not conduct as a solid

sodium oxide conducts when it is a liquid

ions cannot move in a solid

ions can move OR are mobile when liquid Throughout this question, ‘conducts’ and ‘carries charge’ are treated as equivalent terms.DO NOT ALLOW ‘free electrons’ for mobile electronsALLOW poor conductor OR bad conductor‘Sodium oxide only conducts when liquid’ is insufficient to award ‘solid conductivity’ markALLOW ions are fixed in placeIGNORE electronsIGNORE charge carriersIGNORE ‘delocalised ions’ or ‘free ions’ for mobile ionsAny mention of electrons moving is a CON

[5]

72. the energy required to remove one electron from eachatom in one mole of gaseous atoms


ALLOW 3 marks for:the energy required to remove one mole of electrons from one mole of atoms atoms in the gaseous state If no definition, ALLOW one mark for the equation below, including state symbols.X(g) → X+(g) + e– / X(g) – e– → X+(g)ALLOW e for electronIGNORE state symbol for electron

[3]

73. (i) O+(g) → O2+(g) + e– answer must have state symbolsALLOW e for electronALLOW O+(g) – e- → O2+(g)DO NOT ALLOW O+(g) + e– → O2+(g) + 2e–

IGNORE state symbol for electron1

(ii) the O+ ion, is smaller than the O atomORthe electron repulsion/shielding is smallerORthe proton : electron ratio in the 2+ ion is greater than inthe 1+ ion

ALLOW the outer electrons in an O+ ion are closer to the nucleus than an O atomDO NOT ALLOW ‘removed from next shell down’

1

[2]

74. (i) number of protons (in the nucleus) ALLOW proton numberALLOW number of protons in an atomIGNORE reference to electrons

1


(ii) (1s2)2s22p63s23p63d24s2 ALLOW 1s2 written twiceALLOW subscriptsALLOW 4s2 before 3d2+

1

(iii) Mn / manganese and d ALLOW D

1

[3]

75. (i)

δ+ δ +

δ + δ +

H O H

H H

Oδ -δ+

H y d ro g en b o n d

Shape of water with at least one H with δ+ and at least oneO with δ–

H-bond between H in one water molecule and a lone pairof an O in another water molecule

hydrogen bond labelledOR H2O has hydrogen bonding

all marks can be awarded from a labelled diagramIf HO2 shown then DO NOT ALLOW 1st markDipole could be described in words so it does not need to be part of diagram.At least one hydrogen bond must clearly hit a lone pairLone pair interaction could be described in words so it does not need to be part of diagram.DO NOT ALLOW hydrogen bonding if described in context of intramolecular bonding, ie

HO

H3


(ii) no hydrogen bondingORweaker intermolecular forces

DO NOT ALLOW ‘weaker’/ ‘weak’ hydrogen bondingALLOW weaker van der Waals’ forcesALLOW weaker dipole-dipole interactionsDO NOT ALLOW ‘weak intermolecular forces’(ie comparison essential here)DO NOT ALLOW ‘no intermolecular forces’

1

[4]

76. (i) atoms of the same element with different numbers ofneutrons/different masses (1) 1

(ii) 79Br 35 protons, 44 neutrons, 35 electrons (1)81Br 35 protons, 46 neutrons, 35 electrons (1) 2

(iii) (1s2)2s22p63s23p63d104s24p5 (1) 1[4]

77. (i)

+ + + +

+ + +

+ + +

-

----

---

-

-

-- - -

-

---

---

positive ions (1) electrons (1) (must be labelled) 2

(ii) the electrons move (1) 1[3]


78. (i) attraction between oppositely charged ions 1

(ii)

C l

M g-

C l

-

Mg and Cl both with 8 electrons in outer shell, (accept 0 electrons for Mg)Cl must have one dot to seven crosses or vice versa (1)correct charges on each ion (1) 2

(iii) MgCl2 does not conduct when solid because ions are fixed in lattice (1)H2O does not conduct as there are no free charge carriers/watermolecules are uncharged (1)MgCl2 conducts when aqueous because ions are free to move (1) 3

[6]

79. To boil Cl2, van der Waals’ forces/intermolecular forces are broken(with van der Waals/intermolecular spelt correctly) (1)To boil C, covalent bonds are broken (1)covalent bonds are stronger than van der Waals’ forces (1)

[3]

80. (i) H2O NH32 3 (1)2 1 (1) 2


(ii)

N H

H

H 1 0 7 º

shape (1) bond angle labelled on diagram as 107° (1)

120º

S O O

shape (1) bond angle labelled on diagram as 110–120° (1) 4[6]

81. H bonding from lone pair on O of 1 H2O molecule to H of another (1)dipoles shown (1)

Two properties:Ice is lighter than water/ max density at 4°C (1)explanation: H bonds hold H2O molecules apart

/ open lattice in ice/ H-bonds are longer (1)

Higher melting/boiling point than expected (1)explanation: strength of H bonds that need to be broken (1)

must imply that intermolecular bonds are broken

High surface tension/viscosity (1)explanation: strength of H bonds across surface (1)

[6]

82. (i) 1s22s22p63s23p6 1

(ii) 3 1

(iii) 10 1

(iv) ‘dot-and-cross’ of Ca2+ with either 8 electrons or noelectrons. ‘dot-and-cross’ of 2OH– correct 2N.B. H electron and Ca electrons can look the same.

[5]

83. (i) attraction between oppositely charges ions 1

(ii) shared pair of electrons 2‘shared electrons’ scores 1 mark only

[3]


84. (i) attraction of an atom/element for electrons in a (covalent) bond/bonded pair 2

(ii) one element attracts bonded pair more/is more electronegative than other

– on more electronegative atom and on less 2

electronegative element in example

May need to look for these marks below if not given here.[4]

85. H–bond shown between H of one molecule and O, N or F ofanother H-bond shown going to a lone pair

[2]

86. (a) 3

element structure bonding

Mg giant metallic Si giant covalent S simple covalent

1 mark for each correct row

(b) Si has strong forces between atoms/covalent bonds are broken P has weak forces between molecules/intermolecular forces/van der Waals’ forces are broken 2

(c) From Na Al, no of delocalised electrons increases charge on positive ion increases/ionic size decreases/charge density increases attraction between ions and electrons increases/metallic bonding gets stronger 2

[7]


87. (i) 2Na(s) Cl2(g) 2NaCl(s) 1st mark for equation 22nd mark for state symbols

(ii) Giant ionic (lattice) or 3D with alternating Na and Cl– 2

[4]

88. (a) 2

1, 2 or 3 p orbitals are OK

(b) d orbital 2

p sub-shell 6

3rd shell 18 3

(i)

(ii) 2

2s and 2p labels Ignore any superscripted numbers.8 electrons in correct levels with arrows correctly shown

[7]


89. (i) Energy change when each atom in 1 mole of gaseous atoms loses an electron (to form 1 mole of gaseous 1 ions). 3

(ii) O2+(g) O3+(g) e− 21 mark for correct species; 1 mark for state symbolsNo charge required on electron.Ignore (g) on e

(iii) Large difference between 6th and 7th IEs 2marking a different shell (closer to nucleus)

allow ‘inner shells’/new shell/full shell/first shellmarking points independent.not sub-shell or orbital

[7]

90.

O

Na

+2-

Na

+

Also accept Na with full shell as long as it contains ‘x’s(as in example above)

Ignore any inner shells

correct dot and cross correct charges

[2]

91. (i) 2Na O2 Na2O2 1

(ii) Na2O2 2H2O H2O2 2NaOH 1

correct covalent bonds shown (iii) electron count (14) for rest of molecule correct 2

[4]


92. (i) (trigonal) pyramidal 1

(ii) electron pairs repel/bonds repel/electron pairs get as far apart as possible

lone pairs repel more/forces ‘them’ closer

4 electron pairs surround central atom or N 3/diagram with 3 bonds and a lone pair

[4]

93. Original solution contains ions/there are mobile ions

Charge carriers removed as reaction takes place/as solid forms/ as BaSO4 forms/as water forms 2

[2]

94. generalNaCl: ionic/has ionic bonds Beware of contradictions for this mark, especiallyreference to intermolecular forces.Ignore ‘atoms’. 2

graphite: covalent/giant molecular/macromolecular Ignore van der Waals’, intermolecular, molecules

-------------------------------------------


conductivity

NaCl: ions cannot move/no free ions (or electrons) /mobile ions only in solution or when molten

graphite: 2

delocalised electrons/free electrons (between layers)/electrons conduct

Ignore lone pair

melting point

both graphite and NaCl:bonds are strong/bonds difficult to break / 1large amount of energy is needed to break bonds

solubility

NaCl: Water is polar/water has a dipole/ions interacts with water molecules

Graphite: no interaction with water/no intermolecular forces with water/ 2graphite is non-polar

QWC: At least 2 complete sentences in whichthe meaning is clear. 1

[8]


95. (i)

io n isa tio n

d eflec tio n

to th e p u m pac ce le ra tin g

d e te c tio n

......

.. .. .... .. ....... .. .... ..

protons neutrons electrons25Mg 12 13 1226Mg 12 14 12 2

(ii) 1s22s22p63s2

24 78.60/100 25 10.11/100 26 11.29/100 1

(iii) = 24.33 (calc value: 24.3269. This scores one mark)24.32 with no working, award 1 mark only.24.3 with no working, no marks (Periodic Table value) 2

[5]

96. (i)

positive ions electrons (must be labelled)If Mg2+ shown then must be correct: Mg+ not worthy 2

(ii) electrons move 1[3]

97. (i) Oxidation state goes from 0 in O2 2 in MgO 2

(ii)

M g

2+ 2–

or with Mg full shell.correct dot and cross ; correct charges 2

[4]

98. (i) mark vertically:

H2O NH3


2 3

2 1 2

3D Diagram required or diagram with name

(ii) labelled bond angle requiredNH3 pyramidal molecule shown 107 (106-108)SO2 non-linear molecule shown 110 – 130 4

[6]

99. (i) oxygen/ nitrogen is more electronegative/molecule has atoms with different electronegativities/oxygen/more electronegative atom … attracts bondedelectron pair more 1

(ii) H bonding from N of 1 NH3 molecule to H of another NH3

molecule with a Hδ+ shown and a Nδ– shownwith lone pair involved in bond2nd mark is available from water molecule(s) 2

[3]

100. ice is less dense than water

hydrogen bonds hold H2O molecules apart in ice /hydrogen bonds cause an open lattice structure 2

[2]

101. (a) Energy change when each atom in 1 moleof gaseous atomsloses an electron (to form 1 mole of gaseous 1 ions). 3


(b) From Li N, ionisation energy increasesnumber of protons/nuclear charge increasesnuclear attraction increases / shell drawn in by increasednuclear charge/ atomic radius decreasesacross period, electrons added to same shell

Not same subshellFrom Be B, ionisation energy decreasesfor B, electron is removed from a p sub-shell/porbital/different sub-shellwhich has a higher energy 7

watch for distinction between nuclear attraction andnuclear charge in candidates’ scripts.Also watch for confusion between shell and subshell.

AlSharp rise in successive ionisation energy between 3rd and4th IEmarking a change to a new or different shell / there are 3electrons in the outer shell 3

mention of ‘orbital’ or ‘sub-shell cancels ‘shell mark’ Each marking point for Al is independent

QoWC: links together two pieces of informationcorrectly within two of the sections below:1. General trend across period2. Be to BSuccessive ionisation energies

[13]

102. (i) 107 (accept any angle in the range 108 91) 1

(ii) electron pairs repel electron pairs/bonds go as far apart as possible

lone pairs repel more 2[3]


103. (i) Ca+(g) Ca2+(g) e−

Equation with correct charges and 1 electron lost state symbols ‘−’ not required on ‘e’ 2

(ii) same number of protons or same nuclear charge attractingless electrons/electron removed from an ion/less electron-electron repulsion (not less shielding)/ion is smaller 1

(iii) atomic radii of Sr > atomic radii of Ca/Sr has electrons in shell further from nucleus than Ca/Sr has electrons in a higher energy level/Sr has more shells Therefore less attraction Sr has more shielding than Ca (‘more’ is essential) 3

increased nuclear charge is outweighed / despite increased nuclearcharge …..by at least one of the factors above

[6]

104. attraction between oppositely charged ions/

oppositely charged atoms 1

For CaO: correct dot and cross ; correct charges

For CO2: correct dot and cross 3

1s22s22p63s23p6 1[5]

105. (i) dative covalent, bonded pair comes from same atom/ 1electron pair is donated from one atom/both electrons are from the same atom

(ii) Ca(NO3)2 CaO 2NO2 ½O2 or double equation with 2/2/4/1 1

[2]


106. High boiling point or difficult to break linked to strong bonds in the rightcontext within Li or C 1

Li conducts by delocalised/free/mobile electrons structure: giant metallic 3

or ‘ ions with a sea of electrons’ for giant mark

C conducts by delocalised/free/mobile electrons structure: giant covalent

with layers 4

N No mobile charge carriers/electrons/ions to conduct electricity

simple molecular structure/made of N2 molecules

low boiling point or easily broken due to 3

intermolecular forces/

van der Waals’ forces

QWC: At least 2 complete sentences in which the meaning is clear. 1[12]

107. 1s22s22p2 [1]

108. CO2: correct covalent bonds around carbon outer shell electrons correct

(must be ‘dot AND cross’ or electron source clearly shown(different coloured for source?)

[2]

109. correct dot and crosses correct charges

[2]



(ii) increasing nuclear charge/number of protons electrons experience greater attraction or pull / atomicradius decreases / electrons added to same shell /same orsimilar shielding 2

(iii) In B, electron being removed is at a higher energy /In Be, electron being removed is at a lower energy

An s electron is lost in Be AND a p electron is lost in B 2[7]

111. uneven distribution of electrons instantaneous /oscillating/changing/temporary/transient/dipole on one atom causes an induced/resultant dipole on anothermolecule/atom

chlorine gas; bromine liquid; iodine solid/volatility decreases from Cl2 Br2 I2/boiling point increases from Cl2 Br2 I2/stronger forces are broken from Cl2 Br2 I2

number of electrons increases down group

greater/more van der Waals’ forces / induced dipole-dipole interactions / forces between the molecules

[6]

112. 1s22s22p63s23p63d24s2 [1]

113. (i)

+ + + +

+ + +

+ + +

-

----

---

-

-

-- - -

-

---

---

positive ions electrons (must be labelled) 2

(ii) electrons move 1[3]


114. simple molecular 2[2]

115. (i) First ionisation (energy) 2

Ra(g) Ra+(g) e− 1 mark for equation1 mark for state symbols‘‘ not required on ‘e’ 2

(ii) atomic radii of Ra > atomic radii of Ca/Ra has electrons in shell further from nucleus than Ca/Ra has more shells

Ra has more shielding than Ca : ‘more’ is essential

Ra electron held less tightly/less attraction on electron 3[7]

116. (i) Cl2 2I− I2 2Cl− 21 mark for species.1 mark for balancing

(ii) Cl atom is smaller/has less shells electron to be captured will be attracted more 2

[4]

117. (i) H bonding from O of 1 H2O molecule to H of another dipoles shown with lone pair involved in bond 3

(ii) Two properties from:Ice is lighter than water/ max density at 4C explanation: H bonds hold H2O molecules apart

/ open lattice in ice/ H-bonds are longer

Higher melting/boiling point than expected explanation:

strength of H bonds that need to be broken must imply that intermolecular bonds are broken

High surface tension/viscosity explanation strength of H bonds across surface 4

[7]


118. NH3: 107 (range 106 108)electron pairs repel other electron pairs lone pair has more repulsion electron pairs get as far apart as possible

[4]

119. (i) 1s22s22p63s23p6..........3d104s24p5 2

Award 1 mark for p5.

(ii) Highest energy sub-shell/sub-shell/being filled is the psub-shell/outer electrons are in a p (sub-shell/orbital/shell) 1

[3]

120. shared pair of electrons i.e. ‘shared electrons’ is worth 1 mark. pair of electronsfor second mark

[2]

121. H2O: all correct including lone pairs around O

CO2: correct covalent bonds around carbon lone pairs added around oxygen atoms

(must be ‘dot AND cross’ or electron source clearly shown(different coloured for source is OK)

[3]


122. (i) molecule shown as non-linear

angle: 104 - 105

molecule shown as linear 4

(ii) angle: 180

shape of H2Oshape of CO2

Electron pairs repel/groups (or regions) of electrons 2repel/electron pairs get as far apart as possible

Oxygen in water surrounded by 4 areas of electrondensity/2 bonds and 2 lone pairs

ANDCarbon in CO2 surrounded by 2 regions of electrondensity/2 double bonds

[6]

123. (i) Attraction of electrons in a bond towards an atom 2

(ii) CO2 is symmetrical/H2O is not symmetrical In CO2, dipoles cancel/in H2O, the dipoles don’t cancel 2

[4]

124. (a) Energy change when each atom in 1 mole

of gaseous atoms 3

loses an electron (to form 1 mole of gaseous 1 ions).

(b) increasing nuclear charge/number of protons

electrons experience greater attraction or pull/atomicradius decreases/electrons added to same shell/same orsimilar shielding 2

[5]


125. (i)

+– – –

––– – – –

–––– – – –

––– – –

+ ++ + + +

+++

positive ions/cations and negative electrons Can be described in words only for both marks 2

(ii) contain free/mobile/delocalised electrons 1[3]

126. (i) shared pair of electrons 2i.e. ‘shared electrons’ is worth 1 mark. Pair of electrons forsecond mark

(ii) correct dot-and cross diagram 1[3]

127. (i) electrostatic attraction between oppositely charged ions 2(charged or electrostatic for 1st mark)

(ii) correct dot-and cross diagram correct charges 2

(iii) Mg Mg2+ 2e− F2 2e− 2F− 2–sign not required with electron

(iv) solid: ions cannot move /in fixed positions in lattice solution: ions are free to move 2

[8]

128. H2OH bonding from O of 1 molecule to H of another dipoles shown or described 3with lone pair of O involved in the bond

CH4van der Waals’ forces from oscillating dipoles/ temporarydipoles/ transient dipoles/ instantaneous dipoles

leading to induced dipoles caused by uneven distribution of electrons 3

[6]


129. Two properties from:Ice is less dense/lighter than water/floats on water/ max densityat 4C

explanation: H bonds hold H2O molecules apart/ open lattice in ice/ H-bonds are longer 2

Higher melting/boiling point than expected Not just highAccept: ‘unusually high/strangely high/relatively high’

explanation: H bonds need to be broken 2must imply that intermolecular bonds are broken

High surface tension explanation strength of H bonds across surface

mark 2 properties only 4 max

QoWC over whole question 1 legible text with accurate spelling, punctuationand grammar

[5]

130. Xe has a bigger atomic radius OR Xe has more shells ALLOW Xe has more energy levelsALLOW Xe has electrons in higher energy levelALLOW Xe has electrons further from nucleusIGNORE Xe has more orbitals OR more sub-shellsDO NOT ALLOW ‘different shell’ or ‘new shell’

Xe has more shielding

ALLOW More screeningThere must be a clear comparison ie more shielding OR increased shielding.i.e. DO NOT ALLOW Xe ‘has shielding’ALLOW Xe has more electron repulsion from inner shells

The nuclear attraction decreasesOR Outermost electrons of Xe experience less attraction (to nucleus)OR Increased shielding / distance outweighs the increased nuclear charge ORA throughout

ALLOW Xe has less nuclear pullIGNORE Xe has less effective nuclear chargeDO NOT ALLOW nuclear charge for nuclear attraction

[3]


131. Advantageremoves or kills bacteria OR kills germs ORkills micro-organisms OR make it safe to drinkOR sterilises water OR disinfects water

ALLOW to make water potableIGNORE virusIGNORE ‘purifies water’DO NOT ALLOW ‘antiseptic’

Disadvantageit is toxic OR poisonous OR could form chlorinated hydrocarbons

ALLOW forms carcinogens OR forms toxinsIGNORE harmfulDO NOT ALLOW ‘it causes cancer’DO NOT ALLOW “It kills you”

[2]

132. 3d10 4s2 4p5

ALLOW 4s2 3d10 4p5

ALLOW subscripts or 3D10

ALLOW answers with 1s2 2s2 2p6 3s2 3p6 appearing twice[1]

133. (i) Cl2 + 2Br– → Br2 + 2Cl– IGNORE state symbolsALLOW any correct multiple including fractions

1

(ii) Yellow / orange / red / brown ALLOW any combination of these, but no others

1[2]

134. (i) Disproportionation ALLOW versions which sound the sameDO NOT ALLOW disproportional OR disproportionate OR disproportion

1


(ii) Cl2 + 2NaOH → NaClO + NaCl + H2O ALLOW multiples for either equation

3Cl2 + 6NaOH → NaClO3 + 5NaCl + 3H2OALLOW 3Cl2 + 6NaOH → 2NaClO3 + 4NaCl + 3H2

Cl2 and NaOH as reactants AND NaClO3 and NaCl as products

Rest of the equation 3

(iii) NaClO4 ALLOW Na3ClO5 etc

1[5]

135. (i) Potassium AND argon ALLOW K and Ar

1

(ii) They are arranged in increasing atomic numberORNeither would show properties OR trends of rest of groupORNeither would show properties OR trends of rest of periodORThey are arranged by electron configuration

ALLOW any correct property differencee.g. This would place a reactive metal in the same group as noble gasesALLOW they do not fit in with the rest of the group

1[2]

136. (i) 2Mg + O2 → 2MgO ALLOW multiples. Correct species must be seenIGNORE state symbols

1


(ii) Fizzes OR bubbles OR gas produced OR effervescing DO NOT ALLOW ‘carbon dioxide gas produced’DO NOT ALLOW ‘hydrogen produced’ without ‘gas’

Mg dissolves OR Mg disappears OR a solution is formed ALLOW ‘it for Mg’IGNORE Mg reactsIGNORE temperature changeIGNORE steam produced

2

(iii) Quicker OR more vigorous OR gets hotterMUST be a comparison of a reaction observation, not just ‘more reactive’ALLOW any comparison of greater rate including more bubbles etc.DO NOT ALLOW more gas produced

1[4]

137. (a) (i) white precipitate OR white solid DO NOT ALLOW goes white / cloudy / milky / off-whiteDO NOT ALLOW creamy white precipitateALLOW milky white precipitate

1

(ii) Ag+(aq) + Cl–(aq) → AgCl(s)

Balanced equation correct

ALL state symbols correct ALLOW 2 marksAgNO3(aq) + Cl–(aq) → AgCl(s) + NO3

–(aq)(equation mark and state symbol mark)ALLOW 1 mark for:AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)(state symbol mark)ALLOW 1 mark for the state symbols for THESEbalanced equation ONLY:Ag2+(aq) + 2Cl–(aq) → AgCl2(s)Ag(aq) + Cl(aq) → AgCl(s)

2

(iii) (precipitate) dissolves OR disappears OR goescolourless OR goes clear

ALLOW forms a solution1

(b) (i) removes or kills bacteria OR kills germs ORkills micro-organisms OR make it safe to drink ORsterilises water


ALLOW to make water potableIGNORE virusDO NOT ALLOW ‘purifies water’DO NOT ALLOW ‘antiseptic’

1

(ii) it is toxic OR poisonous OR could form chlorinatedhydrocarbons

ALLOW forms carcinogens OR forms toxinsDO NOT ALLOW harmfulDO NOT ALLOW ‘it causes cancer’(chlorine is not a carcinogen)DO NOT ALLOW ‘irritates lungs’

1

(c) (i) Cl2 is 0 AND HCl is –1 AND HClO is (+)1 ALLOW 1–ALLOW 1+

1

(ii) It has been both oxidised and reducedORIts oxidation state has increased and decreased

it has been oxidised (from 0) to +1 ANDit has been reduced (from 0) to –1 (These two points together subsume the first markingpoint)

ALLOW ‘chlorine’ OR ‘it’DO NOT ALLOW chlorIDEIF CORRECT OXIDATION STATES IN (i), ALLOW 2marks for:it is oxidised to form HClOit is reduced to form HCl

2

(iii) Cl2 + 2NaOH → NaClO + NaCl + H2O IGNORE state symbols

1


(d) (i) 2ClO2 → Cl2 + 2O2ORClO2 → ½Cl2 + O2

IGNORE state symbols1

(ii) divides each % by correct Ar:

i.e. 0.168.56:

5.350.42:

0.120.1

OR1.20, 1.18, 3.55

HClO3ALLOW 1 mark for empirical formula of HCl2O6(use of atomic numbers)ALLOW 1 mark for empirical formula of H3Cl3O(upside-down expression)ALLOW ECF for use of incorrect Ar values to getempirical formula but only if no over-roundingALLOW 2 marks for correct answer of HClO3

2

(iii) the oxidation number of chlorine ALLOW ‘the oxidation state of chlorine ORoxidation number of chlorine is 5’DO NOT ALLOW ‘it’ instead of ‘chlorine’DO NOT ALLOW ‘the oxidation state OR number ofchlorIDE is 5’

1

[14]


138. (a) (i) Magnesium ions have a greater charge

Magnesium has more(delocalised OR outer) electrons

Magnesium has greater attraction between ions andelectrons OR has stronger metallic bonds

USE annotations with ticks, crosses, ecf, etc for this part.ALLOW REVERSE ARGUMENTe.g. sodium ions have a smaller chargeALLOW Mg2+ / Mg ion / Na ion / Na+ ionALLOW ‘charge density’ as alternative to ‘charge’ALLOW REVERSE ARGUMENTe.g. sodium has fewer electronsALLOW REVERSE ARGUMENTe.g. sodium has less attractions between ions andelectronsOR has weaker metallic bonds

3

(ii) Cl2 OR S8 has intermolecular OR van der Waals’ forces

S8 has stronger intermolecular forces OR van derWaals’ forces than Cl2

ORS8 has more electrons

ALLOW REVERSE ARGUMENT ie Cl2 has weakerintermolecular forces OR van der Waals’ forcesDO NOT ALLOW comparison involving covalent bondsALLOW REVERSE ARGUMENTCl2 has fewer electrons

2


(b) nuclear charge increases/ protons increase

electrons added to the same shellORscreening OR shielding remains the same

greater attraction OR greater pull USE annotations with ticks, crosses, ecf, etc forthis part.Nuclear OR proton(s) OR nucleus spelt correctlyONCEIGNORE ‘atomic number increases’IGNORE ‘nucleus gets bigger’‘charge increases’ is not sufficientALLOW ‘effective nuclear charge increases’ OR‘shielded nuclear charge increases’IGNORE reference to atomic radius staying the sameALLOW shielding is similarDO NOT ALLOW extra shieldingA comparison must be included:

i.e. ‘greater pull’, ‘more pull’, ‘held more tightly’;3

[8]

139. (a) BaO Ba3N2

Treat any shown charges as working and ignore.Treat B for Ba as a slip

2

(b) (i) 3.13711.0

mark is for the working out which MUST lead to the correct answer of 8 × 10–4 up to calculator value

1

(ii) 19.2ORcalculated answer to (b)(i) × 24000

ALLOW 19 up to calculator value.1


(iii) 8.0 × 10–3

ORcalculated answer to (b)(i) × 10

ALLOW 8.01 × 10–3 up to calculator value1

(iv) any pH > 7 but <15 ALLOW a correct range of pH.

1

(c) Less barium to react ORsome barium has already reacted

ALLOW less volume because contains some BaO or Ba3N2

1

(d) reactivity increases (down the group)

atomic radii increase ORthere are more shells


the nuclear attraction decreases ORIncreased shielding and distance outweigh theincreased nuclear charge

easier to remove (outer) electrons ORionisation energy decreases

USE annotations with ticks, crosses, ecf, etc forthis part.DO NOT ALLOW more orbitals OR more sub-shells‘More’ is essentialALLOW ‘more electron repulsion from inner shells’ALLOW ‘nuclear pull’IGNORE any reference to ‘effective nuclear charge’ALLOW easier to form positive ion

5

[12]


140. CaCO3(s) → CaO(s) + CO2(g)equation state symbols

state symbols are dependent on correct formulae of CaCO3, CaO and CO2DO NOT ALLOW the ‘equation mark’ if O2 is seen on both sides (but note that the ‘state symbol mark’ may still be accessible)

[2]

141. (i) Ca(OH)2 IGNORE charges, even if wrong

1

(ii) Ca(NO3)2 IGNORE charges, even if wrong

1

[2]

142. (i) outer electrons closer to nucleus OR radii decreases

nuclear charge increasesOR protons increase

electrons added to the same shellORscreening OR shielding remains the same

IGNORE ‘atomic number increases’IGNORE ‘nucleus gets bigger’‘charge increases’ is not sufficientALLOW ‘effective nuclear charge increases’ OR‘shielded nuclear charge increases’ALLOW shielding is similar

3


(ii) atomic radii increase ORthere are more shells


the nuclear attraction decreasesORIncreased shielding / distance outweigh the increasednuclear charge

ALLOW electrons in higher energy levelALLOW electrons are further from the nucleusDO NOT ALLOW more orbitals OR more sub-shellsDO NOT ALLOW different shell or new shellThere must be a clear comparison: e.g. ‘more shielding’, ‘increased shielding’. i.e. DO NOT ALLOW just ‘shielding’.ALLOW ‘more electron repulsion from inner shells’Nuclear OR proton(s) OR nucleus spelt correctly ONCE ALLOW ‘nuclear pull’IGNORE any reference to ‘effective nuclear charge’

3

[6]

143. van der Waals’ forces OR induced dipole interactions

number of electrons increases

Down the group, intermolecular forces / van der Waals’forces increaseORDown the group, more energy needed to breakintermolecular / van der Waals’ forces

electron(s) must be seen and spelt correctly ONCEALLOW number of electron shells increasesALLOW iodine has most electronsALLOW chlorine has the least electronsFor ‘Down the group’ALLOW ‘Increase in boiling points’ or ‘Molecules get bigger’

[3]

144. (i) goes brown ALLOW yellow OR orange OR any shade of yellow, orange and brown, e.g. reddish-brownIGNORE precipitate

1


(ii) iodine and (potassium) chloride

Cl2 + 2I– → I2 + 2Cl–

DO NOT ALLOW formulae (i.e. names essential)ALLOW any correct multiple including fractionsIGNORE state symbols

2

(iii) chlorine / Cl2 is more reactive (than iodine)ORchlorine / Cl2 is a more powerful oxidising agent

ALLOW chlorine is better at electron capture OR chlorine attracts electrons moreALLOW iodine is less reactive (than chlorine)ALLOW iodide (ion) / I– is a stronger reducing agentDO NOT ALLOW Cl is more reactiveDO NOT ALLOW explanation in terms of displacementDO NOT ALLOW chlorine is more electronegative

1

(iv) goes purple / violet / lilac / pink ALLOW pink OR any combination of purple, violet, lilac and pink

1

[5]

145. (i) iodide has been converted to iodine (1)(with correct use and spelling of iodide and iodine)The 1st experiment shows that bromine is more reactive than iodine (1)The 2nd experiment shows that chlorine is more reactive than bromine (1)Accept 1 mark for 2nd and 3rd marking points if the correct reactivityorder of chlorine > bromine > iodine has been stated. 3

(ii) Br2 + 2I– 2Br– + I2 (1) 1[4]

146. add AgNO3/Ag+ (to a solution of the food) (1)Ag+(aq) + Cl–(aq) AgCl(s) (1)degree of cloudiness/whiteness/intensity indicates relative quantity (1)sodium ion content needs to be determined as well (1)

[4]


147. (i) S (1) 1

(ii) Al (1) 1

(iii) B (1) 1

(iv) Ca (1) 1

(v) K (1) 1

(vi) K (1) 1[6]

148. (i) atomic radii decrease /similar shielding /electrons added to same shell (1)number of protons in the nucleus increases (1)nuclear attraction increases (1) 3

(ii) Na2+(g) Na3+(g) + e– : equation and state symbols (1) 1

(iii) large jump (in energy) between the 4th and 5th ionisation energies (1)four electrons in outer shell so element is Si (1) 2

[6]

149. (i) because Ca has changed from 0 to +2 (1)and H has changed from +1 to 0 (1) 2

(ii) Calcium reacts with water producinghydrogen/H2/calcium/hydroxide/Ca(OH)2 (1) (i.e. one product)Ca(s) + H2O(l) Ca(OH)2(aq) + H2(g) (1) (i.e. full equation)Equation would subsume both two marks 2

[4]

150. atomic radii of Rb atomic radii of elements above/Rb has electrons in shell further from nucleus /Rb has more shells

Rb has more shielding ( ‘more’ is essential)

(increased) nuclear charge is outweighed /despite increased nuclear charge …..by at least one of thefactors above/less attraction/ held less tightly

[3]


151. (a) 3

element structure bonding

Mg giant metallic Si giant covalent S simple covalent

1 mark for each correct row

(b) Si has strong forces between atoms/covalent bonds are broken P has weak forces between molecules/intermolecular forces/van der Waals’ forces are broken 2

(c) From Na Al, no of delocalised electrons increases charge on positive ion increases/ionic size decreases/charge density increases attraction between ions and electrons increases/metallic bonding gets stronger 2

[7]


152. With Br–, goes yellow/orange/red‘precipitate’ makes this incorrect.

With I–, goes purple/brown/brown ‘precipitate’ should be ignored

Cl2 2Br– Br2 2Cl–

Cl2 2I– I2 2Cl–

Or full equations using soluble halides, eg NaBr

If both equations given with correct species but not

balanced, award 1 mark

reactivity trend: Cl more reactive than both Br and I/

Cl is the most reactive

Cl (atoms) are smaller (ora) /

attraction for electrons or electron affinity is greater / 6

Cl is a stronger oxidising agent

ignore any reference to ‘electronegativity’.

QoWC: At least 2 sentences in which the meaning isclear. 1

[7]

153. (a) add AgNO3 /add Ag+ 3ignore ammoniawhite (precipitate)/goes white/precipitate that dissolves indilute NH3(aq)

Ag+ Cl− AgCl (ignore state symbols)

(b) add NaOH 2

Cl2 2NaOH NaCl NaClO H2O

or partial or completely ionic equation:Cl2 2NaOH 2Na+ ClO– Cl– H2O/Cl2 2OH– ClO– Cl– H2O

[5]


154. number of electrons/electron shells increases down group

van der Waals’ forces/induced dipoledipole interactions

forces greater Cl2 < Br2 < I2 [3]

155. (i) They have different numbers of protons/Ba has one more proton/Ba has 56 p+; Cs has 55 p+ 1(ignore electrons: any mention of ‘neutrons’ is wrong)

(ii) s 1

(iii) Cs to Ba: nuclear charge increases/more protons electrons are in: the same shell/sub-shell/orbital/similar shielding/same shielding 3attraction increases/pull increases …….ORA

(iv) smaller 2shell has been lost/less shielding/less electronrepulsion/proton : electron ratio larger

mark separately[7]

156. (i) loss (of electrons) 1

(ii) Ba 0 ()2 (accept 2) 2

[3]

157. (i) MgO has reacted with CO2 1

(ii) Solid dissolves / disappearsFizzing / bubbles 2MgO 2HCl MgCl2 H2OMgCO3 2HCl MgCl2 CO2 H2Oboth reactions form magnesium chloride/MgCl2 3

[6]


158. (i) goes yellow/orange/brown 1

(ii) Cl2 2Br– Br2 2Cl–

ORCl2 2KBr Br2 2KCl1 mark for species.1 mark for balancing 2

(iii) An electron is being gainedCl atoms are smaller/less shells (ora) In Cl, attraction for electrons is greater 3

[6]

159. (a) (i) Amount of substance that has the same number ofparticles as there are atoms in 12 g of 12C/6 1023/ Avogadro’s Number 1

(ii) moles = 1000120275.0

= 0.0330 mol

moles Cl2 = 20330.0

= 0.0165 mol 1(iii) volume Cl2 = 0.0165 24000 = 396 cm3 / 0.396 dm3

792 cm3 worth 1 mark (no molar ratio)1584 cm3 worth 1 mark (x 2)units needed. 2

(iv) bleach / disinfectant /sterilising /killing germs 1

(b) NaClO3 1[6]

160. (a) Energy change when each atom in 1 moleof gaseous atomsloses an electron (to form 1 mole of gaseous 1 ions). 3


(b) From Li N, ionisation energy increasesnumber of protons/nuclear charge increasesnuclear attraction increases / shell drawn in by increasednuclear charge/ atomic radius decreasesacross period, electrons added to same shell

Not same subshellFrom Be B, ionisation energy decreasesfor B, electron is removed from a p sub-shell/porbital/different sub-shellwhich has a higher energy 7

watch for distinction between nuclear attraction andnuclear charge in candidates’ scripts.Also watch for confusion between shell and subshell.

AlSharp rise in successive ionisation energy between 3rd and4th IEmarking a change to a new or different shell / there are 3electrons in the outer shell 3

mention of ‘orbital’ or ‘sub-shell cancels ‘shell mark’ Each marking point for Al is independent

QoWC: links together two pieces of informationcorrectly within two of the sections below:1. General trend across period2. Be to BSuccessive ionisation energies

[13]

161. (i) hydrogen / H2 1

(ii) Sr 2H2O Sr(OH)2 H2 1

(iii) different numbers of moles/atoms/ different Ar valuesso different number of moles of H2 /more moles of Ca(i.e. an attempt to quantify difference) 2

(iv) 8 – 14 1[5]


162. (i) Ca+(g) Ca2+(g) e−

Equation with correct charges and 1 electron lost state symbols ‘−’ not required on ‘e’ 2

(ii) same number of protons or same nuclear charge attractingless electrons/electron removed from an ion/less electron-electron repulsion (not less shielding)/ion is smaller 1

(iii) atomic radii of Sr > atomic radii of Ca/Sr has electrons in shell further from nucleus than Ca/Sr has electrons in a higher energy level/Sr has more shells Therefore less attraction Sr has more shielding than Ca (‘more’ is essential) 3

increased nuclear charge is outweighed / despite increased nuclearcharge …..by at least one of the factors above

[6]

163. (i) 203.3 g mol−1 1Accept 203

(ii) white precipitate / goes white 1

(iii) Ag+(aq) Cl−(aq) AgCl(s)equation state symbols 2AgCl dissolves in NH3(aq)

(iv) AgBr dissolves in conc NH3(aq)/partially soluble in NH3(aq)

AgI insoluble in NH3(aq) 3[7]

164. Cl2: 0 HOCl 1 HCl −1

[4]


165. High boiling point or difficult to break linked to strong bonds in the rightcontext within Li or C 1

Li conducts by delocalised/free/mobile electrons structure: giant metallic 3

or ‘ ions with a sea of electrons’ for giant mark

C conducts by delocalised/free/mobile electrons structure: giant covalent

with layers 4

N No mobile charge carriers/electrons/ions to conduct electricity

simple molecular structure/made of N2 molecules

low boiling point or easily broken due to 3

intermolecular forces/

van der Waals’ forces

QWC: At least 2 complete sentences in which the meaning is clear. 1[12]

166. CaCO3 CaO CO2 state symbols not required

[1]

167. (a) ……Ca(s) …..2 HCl(aq) …….CaCl2(aq) .H2(g). 2

(g) not required for H2

(b) In Ca, oxidation state = 0 and 2In CaCl2, oxidation state = 2 Oxidation number increases from Ca to CaCl2

[4]

168. (i) white precipitate/goes white 1

(ii) Ag Cl– AgCl 1state symbols not required

[2]


169. (i) moles HCl = 2.0 50/1000 = 0.10 1

(ii) moles Ca = ½ moles HCl = 0.050 mass Ca = 40.1 0.050 = 2.00 g / 2.005 g 2(accept 40 0.050 = 2.0 g)(mass Ca of 4.0 g would score 1 mark as ‘ecf’ as molar ratiohas not been identified)

(iii) Ca has reacted with water Ca 2H2O Ca(OH)2 H2

state symbols not required

1st mark for H2 32nd mark is for the rest of the balanced equation

[6]

170. (i) O 1

(ii) AI 1

(iii) P 1

(iv) C/Si 1

(v) N/P 1

(vi) Mg 1

(vii) Na 1

(viii) Si 1[8]


(ii) increasing nuclear charge/number of protons electrons experience greater attraction or pull / atomicradius decreases / electrons added to same shell /same orsimilar shielding 2

(iii) In B, electron being removed is at a higher energy /In Be, electron being removed is at a lower energy

An s electron is lost in Be AND a p electron is lost in B 2[7]


172. uneven distribution of electrons instantaneous /oscillating/changing/temporary/transient/dipole on one atom causes an induced/resultant dipole on anothermolecule/atom

chlorine gas; bromine liquid; iodine solid/volatility decreases from Cl2 Br2 I2/boiling point increases from Cl2 Br2 I2/stronger forces are broken from Cl2 Br2 I2

number of electrons increases down group

greater/more van der Waals’ forces / induced dipole-dipole interactions / forces between the molecules

[6]

173. Reactivity decreases down group/ Cl2 Br2 I2 /

Cl2 displaces Br2 AND Br2 displaces I2

chlorine: Cl2 bromide yellow ………/ orange ……….

bromine: Br2 iodide darker orange/brown or purple in organic solvent

Cl2 2Br− Br2 2Cl−

Br2 2I− I2 2Br− (or full equations)

Cl2 is stronger oxidising agent than Br2AND Br2 is stronger oxidising agent than I2 / 5

Cl2 has greater attraction for electrons than Br2AND Br2 has greater attraction for electrons than I2

QoWC: At least two sentences that show legible text withaccurate spelling, punctuation and grammar so that themeaning is clear. 1

(Mark this from anywhere within Q4)[6]

174. (a) RaCl2 1


(b) Reduction is gain of electrons/decrease in oxidation number

Ra2+ gains 2 electrons Ra/Oxidation state goes from 2 in RaCl2 0 in Ra 2

[3]

175. (i) effervescence/bubbles Ra disappears/dissolves 2

(ii) 8-14 1[3]

176. (i) First ionisation (energy) 2

Ra(g) Ra+(g) e− 1 mark for equation1 mark for state symbols‘‘ not required on ‘e’ 2

(ii) atomic radii of Ra > atomic radii of Ca/Ra has electrons in shell further from nucleus than Ca/Ra has more shells

Ra has more shielding than Ca : ‘more’ is essential

Ra electron held less tightly/less attraction on electron 3[7]

177. CaCO3 reacts with (or neutralises) HCl (or CaCO3 HCl in an equation)

CaCO3 2HCl CaCl2 H2O CO2 (correct equation would score both marks)

[2]

178. Cl2(g) NaOCl(aq) : Cl(0) Cl(1) Cl2(g) NaCl(aq) : Cl(0) Cl(−1) Cl is both oxidised (in forming NaOCl) and reduced (informing NaCl)/disproportionationCl reduces Cl to form NaCl AND Cl oxidises Cl in formingNaOCl

[3]

179. (i) Cl2 2I− I2 2Cl− 21 mark for species.


1 mark for balancing

(ii) Cl atom is smaller/has less shells electron to be captured will be attracted more 2

[4]

180. N has less protons than O (ora) electrons are in same shell/have same or similar shielding weaker nuclear attraction in N (ora) shell drawn in less by nuclear charge in N (ora)

watch for distinction between nuclear attraction and nuclearcharge in candidates’ scripts.

QoWC: links together two statements in at least two ofthe sections (a)(ii), (b) and (c)

[4]

181. (a) Energy change when each atom in 1 mole

of gaseous atoms 3

loses an electron (to form 1 mole of gaseous 1 ions).

(b) increasing nuclear charge/number of protons

electrons experience greater attraction or pull/atomicradius decreases/electrons added to same shell/same orsimilar shielding 2

[5]

182. (From 2 10 18 / down group)

1st ionisation energies decrease/easier to remove electrons electron is further from nucleus/ atomic radius increases/

electron in a different shell/ atoms increase in size (not sub-shell or orbital)

electron experiences more shielding (more is essential here)

distance and shielding outweigh the increased nuclear charge NOT: attraction/pull; effective nuclear charge

[4]

183. Strontium reacts with oxygen/strontium oxide forms/SrO

forms

2Sr O2 2SrO /


Sr ½ O2 SrO [2]

184. (i) In Sr, oxidation number = 0 In Sr(OH)2, oxidation number = ()2

OR

Oxidation number increases from Sr Sr(OH)2 by 2 2

(ii) 0.438/87.6 = 5.00 10−3 / 0.00500 mol 1

(iii) 0.00500 24.0 = 0.120 dm3 (accept 120 cm3) 1

(iv) 0.00500 1000/200 = 0.0250 mol dm−3 1[5]

185. (i) heat 1

(ii) ...3..SrO(s) ...2..Al(s) ...3..Sr(s) ....Al2O3(s) 1

(iii) Molar mass of SrCO3 = 87.6 12 16x3 = 147.6 g mol−1

Mass SrCO3 required = 100 147.6/87.6 = 168 tonnes

Mass of ore needed = mass SrCO3 100/2= 168 100/2 = 8400 tonnes /8425 tonnes (from 168.484931507) (answer depends on rounding)5000 tonnes is 50 100 tonnes: worth 1 mark 3

(iv) 98% waste produced which must be disposing of /madeinto something worthwhile/CO2 being removed bysomething sensible/ 1any sensible comment

[6]


186. Physical states of halogenschlorine gas; bromine liquid; iodine solid/boiling point increases from Cl2 Br2 I2 number of electrons/number of shells increases down group van der Waals’ forces/induced dipole-dipole interactions/AW stronger forces to be broken (between the molecules) 4

Displacementwith chloride, nothing happens with iodide, darker orange/brown/darker yellow/ purple with organic solvent Br2 2I− I2 2Br− (or a full equation, e.g. with NaI)The strength of oxidising power is Cl2 > Br2 > I2 /Reactivity order is Cl2 > Br2 > I2 4

Quality of written communication

organise relevant information clearly andcoherently, using specialist vocabulary whenappropriate;

Evidence should link together two of the marking points:

e.g. size of the intermolecular forces linked totemperature at which a substance changes state /number of electrons linked to magnitude of intermolecularforces/amount of energy needed to overcome forcesorder of reactivity linked to observation 1

The key is a ‘because’ or ‘therefore’: i.e bromine doesn’tdisplace chlorine because it is less reactive.Greater intermolecular forces: therefore more energy needed to break them.

[9]

187. (a) NaClO, oxidation state = 1 NaCl, oxidation state = −1

OR 2Oxidation number decreases from NaClO NaCl by 2

(b) (i) 84/24000 = 3. 5 10−3 mol 1

(ii) 3.5 10−3 mol 1ans to (i)

(iii) 3.5 10−3 1000/5 = 0.70 mol dm−3 1ans to (ii) x 1000/5


(c) molar mass of NaClO = 23 16 35.5 = 74.5 (g mol−1)

concentration = 0.70 74.5 = 52.15 g (dm−3) ans to (iii) x 74.5

bleach is 5.215 g per 100 cm3 and the information is correct(as this value exceeds 4.5%) 3

response depends upon answer to (b)(iii). Could be oppositeargument if ans < 4.5%

ORmolar mass of NaClO = 23 16 35.5 = 74.5 (g mol−1)

moles of NaOCl = 4.5/74.5 = 0.0604 mol (in 100 cm3)

bleach is 10 0.0604 = 0.604 mol dm−3 which is less thananswer to (b)(iii) and therefore label is correct.

response depends upon answer to (b)(iii). Could be oppositeargument if ans 0.604

(d) 2HCl NaClO Cl2 NaCl H2O 2Award one mark for:HCl NaClO Cl2 NaOH

[10]

188. (i) Answer is inclusive of 9 14 inclusive 1

(ii) Ca(s): 1s22s22p63s23p64s2

Ca(OH)2(aq): 1s22s22p63s23p6 2[3]

189. barium atoms are larger

barium atoms have more shielding

this outweighs the increase in nuclear charge

barium electrons are lost more easily/less energy required/ionisation energy decreases

[4]


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