1.
(a)
Mass of the isotope compared to 1/12th
OR
mass 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 C12
ALLOW 2 marks for:
mass of the isotope
mass of 1 / 12th mass of carbon 12
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 + 79.9119
OR
152.0446 (calculator value)
Ar = 152.04
ALLOW Correct answer for two marks
ALLOW 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)
153
Eu has (2) more neutrons
OR
153
Eu has 90 neutrons AND 151Eu has 88 neutrons
ALLOW There are a different number of neutrons
IGNORE Correct references to protons / electrons
DO NOT ALLOW Incorrect references to protons / electrons
1
(ii)
(It has the) same number of protons AND electrons
OR
Both have 63 protons and 63 electrons
ALLOW Same number of protons AND same electron
configuration
DO 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The H+ ion in an (nitric) acid has been replaced by a metal ion
OR 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 atoms
ALLOW Ca OR Calcium for Ca2+.
DO NOT ALLOW Calcium atoms
ALLOW ‘metal’ for ‘metal ion
1
(ii)
2HNO3(aq) + Ca(OH)2(aq) → Ca(NO3) 2 (aq)+ 2H2O(l)
Formulae
Balance AND states
ALLOW multiples
ALLOW (aq) OR (s) for Ca(OH) 2
2
Rainham School for Girls
2
(iii)
Accepts a proton OR accepts H+
ALLOW H+ + OH–→ H2O
ALLOW 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
0.0880  25.0
 2.20  10 –3 mol
1000
OR 0.00220 mol
ALLOW 0.0022 OR 2.2 × 10–3 mol
1
(ii)
Calculates correctly
0.00220
= 1.10 × 10–3 mol
2
OR 0.00110 mol
ALLOW 0.0011 OR 1.1 × 10–3 mol
ALLOW ECF for answer (i)/2 as calculator value or correct
rounding to 2 significant figures or more but ignore trailing
zeroes
1
(iii)
0.00110  1000
 0.0625 mol dm –3
17.60
OR 6.25 × 10–2 mol dm–3
ALLOW 0.063 OR 6.3 × 10–2 mol dm–3
ALLOW ECF for answer (ii) × 1000/17.60
OR
ECF 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
Rainham School for Girls
3
(ii)
142.1
ALLOW 142
ALLOW Mr expressed as a sum
ALLOW ECF from incorrect Mr and x is calculated correctly
x=
(322 .1  142.1)
= 10
18.0
ALLOW ECF values of x from nearest whole number to
calculator value
ALLOW 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 O
ALLOW ECF for third mark for N is oxidised and O is reduced if
incorrect oxidation numbers support this
IGNORE references to strontium
IGNORE references to electron loss OR gain
DO NOT ALLOW ‘One increases and one decreases’
3
Rainham School for Girls
4
(ii)
Calculates correctly:
5.29
 0.0250
Mol of Sr(NO3)2 = 211 .6
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 zeroes
DO 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 gas
i.e. This answer would give one mark
ALLOW 1.5 dm3
ALLOW ECF producing correct volume of NO2 only
i.e. 1.2(0) dm3 would give two marks
OR
ALLOW ECF producing correct volume of O2 only
i.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 of
neutrons’ without mention of same protons OR same
atomic number
1
Rainham School for Girls
5
(ii)
same (number of) electrons (in the outer shell)
OR
same electron configuration OR structure
DO NOT ALLOW different number of protons
IGNORE ‘same number of protons’
IGNORE ‘they are both carbon’ OR ‘they are both the
same element’
1
(iii)
mass of the isotope compared to 1/12th
OR
mass 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
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 C12
ALLOW FOR 2 MARKS:
mass of the isotope
mass of 1/12th mass of carbon  12
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.’
2
[4]
Rainham School for Girls
6
7.
giant covalent (lattice)
layers
Each of the three properties below must be linked to
explanation
good conductor – because it has mobile electrons OR
delocalised electrons OR electrons can move
high melting / boiling point – because strong OR
covalent bonds have to be broken
soft – because there are van der Waals’ forces OR
intermolecular forces OR weak bonds OR weak forces
between the layers
OR
soft – because layers can slide
Use annotations with ticks, crosses etc. for this part.
All five marking points are independent
ALLOW giant atomic OR giant molecular OR
macromolecular
ALLOW planes OR sheets
Allow diagram showing at least two layers
Electron(s) must be spelt correctly ONCE
DO NOT ALLOW ‘strong ionic bonds’ OR strong metallic
bonds.
[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 value
ALLOW
ECF answer to (i) × 6.02 × 1023
ALLOW any value for NA in the range:
6.0 × 1023 – 6.1 × 1023
1
[2]
Rainham School for Girls
7
soft – because there are van der Waals’ forces OR
intermolecular forces OR weak bonds OR weak forces
between the layers
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 multiple
IGNORE state symbols
1
(ii)
when the H+ in an acid is replaced by a metal ion OR an
ammonium 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 pair
ALLOW removes H+
ALLOW forms OH− ions
1
(iv)
132.1
IGNORE units
NO OTHER ACCEPTABLE ANSWER
1
[4]
10.
(a)
(i)
white precipitate OR white solid
DO NOT ALLOW goes white / cloudy / milky / off-white
DO NOT ALLOW creamy white precipitate
ALLOW milky white precipitate
1
Rainham School for Girls
8
(ii)
Ag+(aq) + Cl–(aq) → AgCl(s)
Balanced equation correct
ALL state symbols correct
ALLOW 2 marks
AgNO3(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 THESE
balanced equation ONLY:
Ag2+(aq) + 2Cl–(aq) → AgCl2(s)
Ag(aq) + Cl(aq) → AgCl(s)
2
(iii)
(precipitate) dissolves OR disappears OR goes
colourless OR goes clear
ALLOW forms a solution
1
(b)
(i)
removes or kills bacteria OR kills germs OR
kills micro-organisms OR make it safe to drink OR
sterilises water
ALLOW to make water potable
IGNORE virus
DO NOT ALLOW ‘purifies water’
DO NOT ALLOW ‘antiseptic’
1
(ii)
it is toxic OR poisonous OR could form chlorinated
hydrocarbons
ALLOW forms carcinogens OR forms toxins
DO NOT ALLOW harmful
DO NOT ALLOW ‘it causes cancer’
(chlorine is not a carcinogen)
DO NOT ALLOW ‘irritates lungs’
1
Rainham School for Girls
9
(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 reduced
OR
Its oxidation state has increased and decreased
it has been oxidised (from 0) to +1 AND
it has been reduced (from 0) to –1
(These two points together subsume the first marking
point)
ALLOW ‘chlorine’ OR ‘it’
DO NOT ALLOW chlorIDE
IF CORRECT OXIDATION STATES IN (i), ALLOW 2
marks for:
it is oxidised to form HClO
it is reduced to form HCl
2
(iii)
Cl2 + 2NaOH → NaClO + NaCl + H2O
IGNORE state symbols
1
(d)
(i)
2ClO2 → Cl2 + 2O2
OR
ClO2 → ½Cl2 + O2
IGNORE state symbols
1
(ii)
divides each % by correct Ar:
1.20 42.0 56.8
:
:
i.e.
1.0 35.5 16.0
OR
1.20, 1.18, 3.55
HClO3
ALLOW 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 get
empirical formula but only if no over-rounding
ALLOW 2 marks for correct answer of HClO3
2
Rainham School for Girls
10
(iii)
the oxidation number of chlorine
ALLOW ‘the oxidation state of chlorine OR
oxidation number of chlorine is 5’
DO NOT ALLOW ‘it’ instead of ‘chlorine’
DO NOT ALLOW ‘the oxidation state OR number of
chlorIDE 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)
0.11
137 .3
mark is for the working out which MUST lead to the correct
answer of 8 × 10–4 up to calculator value
1
(ii)
19.2
OR
calculated answer to (b)(i) × 24000
ALLOW 19 up to calculator value.
1
(iii)
8.0 × 10–3
OR
calculated answer to (b)(i) × 10
ALLOW 8.01 × 10–3 up to calculator value
1
(iv)
any pH > 7 but <15
ALLOW a correct range of pH.
1
Rainham School for Girls
11
(c)
Less barium to react OR
some barium has already reacted
ALLOW less volume because contains some BaO or Ba3N2
1
(d)
reactivity increases (down the group)
atomic radii increase OR
there are more shells
there is more shielding OR more screening
the nuclear attraction decreases OR
Increased shielding and distance outweigh the
increased nuclear charge
easier to remove (outer) electrons OR
ionisation energy decreases
USE annotations with ticks, crosses, ecf, etc for
this part.
DO NOT ALLOW more orbitals OR more sub-shells
‘More’ is essential
ALLOW ‘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
electrons
24
12
12
12
25
12
13
12
Mg
Mg
24
Mg line correct
Mg line correct
mark by row
25
2
Rainham School for Girls
12
(ii)
24  78.60  25  10.11  26  11.29
100
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 out
ALLOW 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 atom
OR (weighted) average mass of an atom
relative to 1/12th (the mass)
of (one atom of) 12C
ALLOW The (weighted) mean mass
OR (weighted) average mass of an atom
OR average atomic mass
compared with (the mass of) carbon-12
which is 12
For 1st marking point, ALLOW mean mass of the isotopes
OR average mass of the isotopes
Do NOT ALLOW the singular: isotope
ALLOW 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 (+)2
OR oxidation number increases by 2
ALLOW correct oxidation numbers shown in equation
2nd mark is dependent on identification of Mg
IGNORE electrons
2
Rainham School for Girls
13
(ii)
Mg/solid dissolves OR Mg/solid disappears
OR (Mg/solid) forms a solution
bubbles OR fizzes OR effervesces OR gas produced
IGNORE metal reacts
IGNORE temperature change
IGNORE steam produced
DO NOT ALLOW carbon dioxide gas produced
DO NOT ALLOW hydrogen produced without gas
2
[4]
14.
(i)
M(MgSO4) = 120.4 OR 120 (g mol–1)
1.51
= 0.0125 mol
120.4
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
mol MgSO4 =
2
(ii)
1.57
= 0.0872(2) (mol)
18.0
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]
Rainham School for Girls
14
15.
(i)
mol HCl = 1.50 × 10–2
volume HCl(aq) = 75.0
ALLOW answers to 2 significant figures
ALLOW ecf from wrong number of moles
moles of HCI  1000
i.e
0.200
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)
(ii)
atoms of the same element with different numbers of
neutrons/different masses (1)
79
81
(iii)
Br 35 protons, 44 neutrons, 35 electrons (1)
Br 35 protons, 46 neutrons, 35 electrons (1)
(1s2)2s22p63s23p63d104s24p5 (1)
1
2
1
[4]
Rainham School for Girls
15
18.
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)
(i)
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 : 30.50/18
or 0.4235 : 1.694 or 1 : 4 (1)
Formula = Ca(NO3)2•4H2O (1)
[3]
20.
(i)
(ii)
because Ca has changed from 0 to +2 (1)
and H has changed from +1 to 0 (1)
2
Calcium reacts with water producing
hydrogen/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
percentage
composition
number of
protons
neutrons
electrons
85
Rb
71 to 73
37
48
37
87
Rb
27 to 29
37
50
37
mark
must add
up to 100
ie 1 mark for each atomic structure; 1 for  compositions.
Ar 
(85  72)  (87  28)
/ 85.56
100
= 85.6
Rainham School for Girls
2nd mark for significant figures
2
16
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
(ii)
ratio Rb : Ag : I = 7.42/85.5 : 37.48/108 : 55.10/127
1
or 0.0868 : 0.347 : 0.434
or 1 : 4 : 5
= RbAg4I5
2
[3]
23.
(a)
(b)
(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
2nd mark is consequential on molar ratio given
2
Evidence that the oxidation number of Mn has reduced
and one of the oxidation numbers correct (ie MnO2: ox no
of Mn = 4 or MnCl2: ox no of Mn = 2
The other oxidation number of Mn is correct,
ie in MnO2: ox no of Mn = 4
or in MnCl2: ox no of Mn = 2
2
[5]
Rainham School for Girls
17
24.
(i)
mass = 0.0500  23.0 = 1.15 g
1
(ii)
moles H2 = 0.0250
volume H2 = 0.0250  24 = 0.600 dm3
ecf from calculated moles H2
2
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
(iii)
correct covalent bonds shown
electron count (14) for rest of molecule correct
2
[4]
26.
(i)
loss (of electrons)
1
(ii)
Ba
0  ()2
2
(accept 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 method
mass 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]
Rainham School for Girls
18
28.
(i)
deflection 
accelerating
......
to the pump
ionisation 
detection
.........................
25
Mg
Mg
26
(ii)
(iii)
protons
neutrons
electrons
12
12
13
14
12
12
2
1s22s22p63s2
24  78.60/100  25  10.11/100  26  11.29/100
1
= 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)
2+
2–
Mg
or with Mg full shell.
correct dot and cross ; correct charges
2
[4]
30.
(i)
(ii)
MgO has reacted with CO2
Solid dissolves / disappears
Fizzing / bubbles
MgO  2HCl  MgCl2  H2O
MgCO3  2HCl  MgCl2  CO2  H2O
both reactions form magnesium chloride/MgCl2
1
2
3
[6]
Rainham School for Girls
19
31.
(i)
ratio N : H : S : O =
24.12 6.94 27.61 41.33
:
:
:
:
16
14
32.1
1
=2:8:1:3
Empirical formula = N2H8SO3
N2H4SO3 is worth 1 mark from consistent use of at nos.
(ii)
H2O  2NH3  SO2  (NH4)2SO3
(Award mark for N2H8SO3)
2
1
[3]
32.
(a)
(i)
(ii)
(iii)
(iv)
(b)
Amount of substance that has the same number of
particles as there are atoms in 12 g of 12C/
6  1023/ Avogadro’s Number
0.275 120
moles =
= 0.0330 mol
1000
0.0330
moles Cl2 =
= 0.0165 mol
2
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.
bleach / disinfectant /sterilising /killing germs
NaClO3
1
1
2
1
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)
(ii)
all state symbols (1)
3
CaCO3 fizzes/ gas given off/ gas evolved / carbon dioxide evolved (1)
1
[4]
Rainham School for Girls
20
34.
(i)
(atoms of) same element/same atomic number/number of protons with
different numbers of neutrons/diff masses
1
(ii)
proton
neutron
relative mass 1
1
electron
1
/
1840
negligible
relative charge
1
0
i.e. 1 mark for each correct row
for electron, accept 1/1500 – 1/2000
for charges, accept ; 0; –
−1
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
Ar =
of carbon-12
3
(121  57.21)  (123  42.79)
/ 121.8558
100
= 121.9
2
[5]
Rainham School for Girls
21
36.
(i)
Mass Sb2S3 in stibnite = 5% of 500 kg = 25.0 kg
Moles Sb2S3 =
25.0 10 3
/ 73.5/ 73.529 /73.53/ 74 mol
340
(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
(ii)
2
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 2
ecf 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)
moles CaO =
1.50
= = 0.0267/0.027
56.1
(anywhere)
2
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 =
0.0534 (or 5)  1000
= 21.4 cm3
2.50
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]
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38.
(i)
dative covalent, bonded pair comes from same atom/
electron 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
1
[2]
39.
(i)
203.3 g mol−1
Accept 203
1
(ii)
white precipitate / goes white
1
(iii)
Ag+(aq)  Cl−(aq)  AgCl(s)
equation
state symbols
AgCl dissolves in NH3(aq)
(iv)
2
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
electrons
12
C
6
6
6
13
C
6
7
6
[2]
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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 is
12
2
mass of 1 mole of the isotope/mass of 1 mole of carbon-12
is equivalent to the first mark
“mass of the isotope that contains the same number of
atoms as are in 1 mole of carbon-12”  1 mark (mark
lost 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
In CaCl2, oxidation state = 2
Oxidation number increases from Ca to CaCl2
2
[4]
Rainham School for Girls
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45.
(i)
moles HCl = 2.0  50/1000 = 0.10
(ii)
moles Ca = ½  moles HCl = 0.050
mass Ca = 40.1  0.050 = 2.00 g / 2.005 g
(accept 40  0.050 = 2.0 g)
(mass Ca of 4.0 g would score 1 mark as ‘ecf’ as molar ratio
has not been identified)
(iii)
1
2
Ca has reacted with water
Ca  2H2O  Ca(OH)2  H2
state symbols not required
1st mark for H2
2nd mark is for the rest of the balanced equation
3
[6]
46.
(a)
(i)
(ii)
atoms of same element/same atomic number….. with
different numbers of neutrons/different masses
1
isotope
2
electrons
22
24
22
47
22
25
22
Ti
Ar 
neutrons
46
Ti
(b)
protons
(46  8.9)  (47  9.8)  (48  81.3)
/ 47.724
100
= 47.7
2
[5]
47.
(i)
moles Ti  1.44/47.9  0.0301 mol/0.03 mol
(accept use of answer from (b))
1
(ii)
mass of Cl  5.70-1.44  4.26 g
moles Cl  4.26/35.5  0.120 mol
5.70/35.5  0.161 mol gets 1 mark
2
(iii)
(iv)
Ti:Cl  0.0301 : 0.12  1:4.
Empirical formula  TiCl4
0.0301 : 0.161 mol gives TiCl5 for 1 mark
Ti  2Cl2  TiCl4
(ecf possible from (iii)
covalent
1
1
[5]
48.
(a)
RaCl2
(b)
Reduction is gain of electrons/decrease in oxidation number
Rainham School for Girls
1
25
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)
(b)
(i)
moles HCl  0.108  500/1000  0.054
(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
molar 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
be ‘Not enough’
1
1
3
1
[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.
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/ ammonium
nitrate/ urea/ refrigeration/ cleaning agents/ fertiliser
(if not allowed in (ii) (1)
1
(i)
[4]
Rainham School for Girls
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52.
(i)
79
(ii)
79
Br has two
less neutrons than 81Br
Br have same numbers of protons
and same number of electrons
2
2
[4]
53.
(i)
Number AND type of atoms (making up a
molecule)/number of atoms of each element
Not ratio
1
(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
not PBr2
3
[5]
54.
(i)
fizzing/gas/hydrogen evolved or Mg dissolves/disappears
[an incorrect observation negates this mark]
(ii)
2HCl  Mg  MgCl2  H2
1
[correct formula for MgCl2. Allow equation with HI/MgI2 instead of HCl]
[balancing: e.g. 2HCl  2Mg  2MgCl  H2 will get this mark but
not the 1st]
2
[3]
55.
isotope
protons
nickel-58
28
nickel-60
28
nickel-62
28
neutrons
30
32
34
electrons
28
28
28
For ecf, 3rd column same as first column.
[3]
Rainham School for Girls
27
56.
(i)
(ii)
(iii)
mass spectrometry
mass spec… /mass spectrometer should also be credited
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
carbon-12 is equivalent to first two marks
“mass of the element that contains the same number of
atoms as are in 1 mole of carbon-12”  2 marks (mark lost
because of mass units)
63.0  77.2/100  65.0  22.8/100 / 63.456
1
3
2
= 63.5 (mark for significant figures)
(iv)
copper/ Cu
1
[7]
57.
(i)
(ii)
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)
2nd mark is for the mass of Ni divided by 58.7
number of atoms of Ni = 6.02  1023  0.0341
2
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 levels
ALLOW Xe has electrons in higher energy level
ALLOW Xe has electrons further from nucleus
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IGNORE Xe has more orbitals OR more sub-shells
DO NOT ALLOW ‘different shell’ or ‘new shell’
Xe has more shielding
ALLOW More screening
There 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 decreases
OR 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 pull
IGNORE Xe has less effective nuclear charge
DO NOT ALLOW nuclear charge for nuclear attraction
[3]
61.
(i)
(Electrostatic) attraction between oppositely charged ions.
IGNORE force
IGNORE references to transfer of electrons
MUST be ions, not particles
1
(ii)
Mg shown with either 8 of 0 electrons
AND
S shown with 8 electrons with 2 crosses and 6 dots (or vice versa)
Correct charges on both ions
2-
2+
Mg
S
Mark charges on ions and electrons independently
For 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 required
IGNORE inner shell electrons
Brackets are not required
2
[3]
62.
(i)
Electron pairs in covalent bonds shown correctly using dots and
crosses in a molecule of the F2O
Lone pairs correct on O and both F atoms
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29
O
F
F
Must be ‘dot-and-cross’
circles for outer shells NOT needed
IGNORE inner shells
Non-bonding electrons of O do not need to be shown as pairs
Non-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 pairs
ALLOW ‘bonds’ for ‘bonded pairs’
DO NOT ALLOW ‘atoms repel’
DO NOT ALLOW electrons repel
ALLOW LP for ‘lone pair’
ALLOW BP for bonded pair
ALLOW LP repel more if bonded pairs have already been
mentioned
3
[5]
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30
63.
(i)
(At least) two NH3 molecules with correct dipole shown with at
least one H with δ+ and one N with δ–
DO NOT ALLOW first mark for ammonia molecules with
incorrect lone pairs
DO NOT ALLOW first mark if H2O, NH2 or NH is shown
(Only) one hydrogen bond from N atom on one molecule to a
H 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 bond
ALLOW 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 hit
the lone pair
Hydrogen bond
δN
δ+
H
δ+
δHδ+ H
N
δ+
H
δ+
δ+ H
H
ALLOW 2-D diagrams
ALLOW 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 bonds
OR ice has an open lattice
ORA
ALLOW ice floats for first mark
OR
H2O has a relatively high boiling point OR melting point
ALLOW higher melting OR boiling point than expected
DO NOT ALLOW H2O has a high melting / boiling point
(relatively strong) hydrogen bonds need to be broken
OR a lot of energy is needed to overcome hydrogen bonds
OR hydrogen bonds are strong
ALLOW other properties caused by hydrogen bonding not
mentioned within the specification
E.g. high surface tension – strong hydrogen bonds on the surface
2
[5]
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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 ions
and delocalised electrons
(There is electrostatic attraction between) positive ions and electrons
DO NOT ALLOW as label nuclei OR protons for positive ions
ALLOW labelled diagram of metallic bonding for second and
third marks
Mg
2+ 2+ 2+
2+ 2+ 2+
2+ 2+ 2+
positive ions
delocalised electrons
2+ 2+ 2+
Lattice must have at least two rows of positive ions. If a Mg ion is
shown it must correct charge
ALLOW for labels: + ions, positive ions, cations
DO NOT ALLOW as label nuclei OR protons for positive ions
ALLOW e– or e as label for electron
DO 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 ONCE
ALLOW Cl is a (covalent) molecule
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Cl has van der Waals’ forces (between molecules)
OR
Cl has instantaneous dipole–induced dipoles
OR
temporary dipole–temporary dipole
IGNORE Cl has intermolecular bonding
van der Waals’ forces are weak and metallic bonds are strong
OR
van der Waals’ forces are weaker than metallic bonds
OR
Less 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 structure
ALLOW ECF from any incorrect intermolecular forces
e.g. permanent dipole–dipole from marking point 5
ALLOW vdW easier to break
ORA
[6]
66.
giant covalent (lattice)
layers
Each of the three properties below must be linked to
explanation
good conductor – because it has mobile electrons OR
delocalised electrons OR electrons can move
high melting / boiling point – because strong OR
covalent bonds have to be broken
soft – because there are van der Waals’ forces OR
intermolecular forces OR weak bonds OR weak forces
between the layers
OR
soft – because layers can slide
Use annotations with ticks, crosses etc. for this part.
All five marking points are independent
ALLOW giant atomic OR giant molecular OR
macromolecular
ALLOW planes OR sheets
Allow diagram showing at least two layers
Electron(s) must be spelt correctly ONCE
DO NOT ALLOW ‘strong ionic bonds’ OR strong metallic
bonds.
[5]
67.
(i)
a shared pair of electrons
ALLOW any response that communicates electron pair
ALLOW shared pairs
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1
(ii)
H
N
H
H
Must be ‘dot-and-cross’
circles for outer shells NOT needed
IGNORE inner shells
Non-bonding electrons of N do not need to be shown as
a 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 repel
ALLOW LP for ‘lone pair’
ALLOW BP for bonded pair
3
[5]
68.
(i)
1s22s22p63s23p6
ALLOW subscripts
1
Rainham School for Girls
34
(ii)
+
H
H
N
H
H
‘Dot-and-cross’ diagram to show four shared pairs of
electrons one of which is a dative covalent bond (which
must consist of the same symbols)
IGNORE inner shells
IGNORE ‘+’ 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 liquid
DO NOT ALLOW ions can move when molten
ALLOW 1 mark for:
‘Ions can only move in solution’
2
[6]
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35
69.
regular arrangement of labelled + ions with some attempt
to show electrons
scattering of labelled electrons between other species
OR
a statement anywhere of delocalised electrons (can be in
text below)
metallic bond as (electrostatic) attraction between the
electrons and the positive ions
Lattice must have at least 2 rows of positive ions
If a metal ion is shown (e.g. Na+), it must have the correct charge
ALLOW for labels: + ions, positive ions, cations
If ‘+’ is unlabelled in diagram, award the label for ‘+’ from a
statement of ‘positive ions’ in text below
DO NOT ALLOW as label or text positive atom OR protons OR
nuclei
ALLOW e– OR e as label for electron
DO NOT ALLOW ‘–’ as label for electron
[3]
70.
(i)
4 Na + O2 → 2 Na2O
OR 2 Na + ½ O2 → Na2O
ALLOW correct multiples including fractions
IGNORE state symbols
1
(ii)
(electrostatic) attraction between oppositely charged ions
1
Rainham School for Girls
36
(iii)
+
2–
Na
O
+
Na
Na shown with either 8 or 0 electrons
AND
O shown with 8 electrons with 6 crosses and 2 dots (or
vice versa)
Correct charges on both ions
For 1st mark, if 8 electrons shown around cation then
‘extra’ electron(s) around anion must match symbol
chosen for electrons in cation
Shell circles not required
IGNORE 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 mobile
electrons OR delocalised electrons
OR 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 electrons
ALLOW poor conductor OR bad conductor
‘Sodium oxide only conducts when liquid’ is insufficient to
award ‘solid conductivity’ mark
ALLOW ions are fixed in place
IGNORE electrons
IGNORE charge carriers
IGNORE ‘delocalised ions’ or ‘free ions’ for mobile ions
Any mention of electrons moving is a CON
[5]
72.
the energy required to remove one electron
atom in one mole
of gaseous atoms
ALLOW 3 marks for:
Rainham School for Girls
from each
37
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 electron
IGNORE state symbol for electron
[3]
73.
(i)
O+(g) → O2+(g) + e–
answer must have state symbols
ALLOW e for electron
ALLOW O+(g) – e- → O2+(g)
DO NOT ALLOW O+(g) + e– → O2+(g) + 2e–
IGNORE state symbol for electron
1
(ii)
the O+ ion, is smaller than the O atom
OR
the electron repulsion/shielding is smaller
OR
the proton : electron ratio in the 2+ ion is greater than in
the 1+ ion
ALLOW the outer electrons in an O+ ion are closer to the
nucleus than an O atom
DO NOT ALLOW ‘removed from next shell down’
1
[2]
74.
(i)
number of protons (in the nucleus)
ALLOW proton number
ALLOW number of protons in an atom
IGNORE reference to electrons
1
Rainham School for Girls
38
(ii)
(1s2)2s22p63s23p63d24s2
ALLOW 1s2 written twice
ALLOW subscripts
ALLOW 4s2 before 3d2+
1
(iii)
Mn / manganese and d
ALLOW D
1
[3]
75.
(i)
Hydrogen bond
δ+
H
O
δ+
δ+
H
O
δ-
H δ+
H δ+
Shape of water with at least one H with δ+ and at least one
O with δ–
H-bond between H in one water molecule and a lone pair
of an O in another water molecule
hydrogen bond labelled
OR H2O has hydrogen bonding
all marks can be awarded from a labelled diagram
If HO2 shown then DO NOT ALLOW 1st mark
Dipole 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 pair
Lone 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
O
H
H
3
Rainham School for Girls
39
(ii)
no hydrogen bonding
OR
weaker intermolecular forces
DO NOT ALLOW ‘weaker’/ ‘weak’ hydrogen bonding
ALLOW weaker van der Waals’ forces
ALLOW weaker dipole-dipole interactions
DO NOT ALLOW ‘weak intermolecular forces’
(ie comparison essential here)
DO NOT ALLOW ‘no intermolecular forces’
1
[4]
76.
(i)
(ii)
atoms of the same element with different numbers of
neutrons/different masses (1)
79
81
(iii)
Br 35 protons, 44 neutrons, 35 electrons (1)
Br 35 protons, 46 neutrons, 35 electrons (1)
(1s2)2s22p63s23p63d104s24p5 (1)
1
2
1
[4]
77.
(i)
+ - + - +
- + -
(ii)
+ - +
+ -
+
- +
+
-
positive ions (1) electrons (1) (must be labelled)
2
the electrons move (1)
1
[3]
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40
78.
(i)
attraction between oppositely charged ions
(ii)
1
Cl
Mg
Cl
(iii)
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
MgCl2 does not conduct when solid because ions are fixed in lattice (1)
H2O does not conduct as there are no free charge carriers/water
molecules 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
2
2
Rainham School for Girls
NH3
3
1
(1)
(1)
2
41
N
H
(ii)
H
107º
H
shape (1) bond angle labelled on diagram as 107° (1)
S
O
O
120º
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 no
electrons.
‘dot-and-cross’ of 2OH– correct
N.B. H electron and Ca electrons can look the same.
2
[5]
83.
(i)
attraction between oppositely charges ions
1
(ii)
shared pair of electrons
‘shared electrons’ scores 1 mark only
2
[3]
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42
84.
(i)
(ii)
attraction of an atom/element for electrons
in a (covalent) bond/bonded pair
2
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 of
another
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)
(c)
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
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]
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43
87.
(i)
(ii)
2Na(s)  Cl2(g)  2NaCl(s)
1st mark for equation
2nd mark for state symbols
Giant ionic (lattice) or 3D
with alternating Na and Cl–
2
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]
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44
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−
1 mark for correct species; 1 mark for state symbols
No charge required on electron.
Ignore (g) on e
2
(iii)
Large difference between 6th and 7th IEs
marking a different shell (closer to nucleus)
allow ‘inner shells’/new shell/full shell/first shell
marking points independent.
not sub-shell or orbital
2
[7]
90.
+
2-
Na
+
O
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
(iii)
correct covalent bonds shown
electron count (14) for rest of molecule correct
2
[4]
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45
92.
(i)
(trigonal) pyramidal
(ii)
electron pairs repel/bonds repel
/electron pairs get as far apart as possible
1
lone pairs repel more/forces ‘them’ closer
4 electron pairs surround central atom or N
/diagram with 3 bonds and a lone pair
3
[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.
general
NaCl: ionic/has ionic bonds
Beware of contradictions for this mark, especially
reference to intermolecular forces.
Ignore ‘atoms’.
2
graphite: covalent/giant molecular/macromolecular
Ignore van der Waals’, intermolecular, molecules
-------------------------------------------
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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 /
large amount of energy is needed to break bonds
1
solubility
NaCl:
Water is polar/water has a dipole/
ions interacts with water molecules
Graphite:
no interaction with water/
no intermolecular forces with water/
graphite is non-polar
QWC:
At least 2 complete sentences in which
the meaning is clear.
2
1
[8]
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95.
(i)
deflection 
accelerating
......
to the pump
ionisation 
detection
.........................
25
Mg
Mg
26
(ii)
(iii)
protons
neutrons
electrons
12
12
13
14
12
12
2
1s22s22p63s2
24  78.60/100  25  10.11/100  26  11.29/100
1
= 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)
(ii)
positive ions
electrons
(must be labelled)
2+
If Mg shown then must be correct: Mg+ not worthy
2
electrons move
1
[3]
97.
(i)
Oxidation state goes from 0 in O2
 2 in MgO
2
(ii)
2–
2+
Mg
or with Mg full shell.
correct dot and cross ; correct charges
2
[4]
98.
(i)
mark vertically:
H2O
Rainham School for Girls
NH3
48
2
3
2
1
2
3D Diagram required or diagram with name
(ii)
labelled bond angle required
NH3
pyramidal molecule shown
SO2
non-linear molecule shown
107 
(106-108)
110 – 130 
4
[6]
99.
(i)
(ii)
oxygen/ nitrogen is more electronegative/
molecule has atoms with different electronegativities
/oxygen/more electronegative atom … attracts bonded
electron pair more
1
H bonding from N of 1 NH3 molecule to H of another NH3
molecule with a Hδ+ shown and a Nδ– shown
with lone pair involved in bond
2nd 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 mole
of gaseous atoms
loses an electron
(to form 1 mole of gaseous 1 ions).
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3
49
(b)
From Li  N, ionisation energy increases
number of protons/nuclear charge increases
nuclear attraction increases / shell drawn in by increased
nuclear charge/ atomic radius decreases
across period, electrons added to same shell
Not same subshell
From Be  B, ionisation energy decreases
for B, electron is removed from a p sub-shell/p
orbital/different sub-shell
which has a higher energy
watch for distinction between nuclear attraction and
nuclear charge in candidates’ scripts.
Also watch for confusion between shell and subshell.
Al
Sharp rise in successive ionisation energy between 3rd and
4th IE
marking a change to a new or different shell / there are 3
electrons in the outer shell
mention of ‘orbital’ or ‘sub-shell cancels ‘shell mark’ Each
marking point for Al is independent
QoWC:
7
3
links together two pieces of information
correctly within two of the sections below:
1. General trend across period
2. Be to B
Successive ionisation energies
[13]
102. (i)
(ii)
107
(accept any angle in the range 108
 91)
1
electron pairs repel electron pairs/bonds go as far apart as possible
lone pairs repel more
2
[3]
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50
103. (i)
(ii)
(iii)
Ca+(g)  Ca2+(g)  e−
Equation with correct charges and 1 electron lost
state symbols
‘−’ not required on ‘e’
2
same number of protons or same nuclear charge attracting
less electrons/
electron removed from an ion/
less electron-electron repulsion (not less shielding)/
ion is smaller
1
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 nuclear
charge …..by at least one of the factors above
[6]
104. attraction between oppositely charged ions/
oppositely charged atoms
For CaO: correct dot and cross
1
; correct charges
For CO2: correct dot and cross
3
1s22s22p63s23p6
1
[5]
105. (i)
(ii)
dative covalent, bonded pair comes from same atom/
electron pair is donated from one atom/
both electrons are from the same atom
Ca(NO3)2  CaO  2NO2  ½O2
or double equation with 2/2/4/1
1
1
[2]
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51
106. High boiling point or difficult to break linked to strong bonds in the right
context within Li or C
Li
conducts by delocalised/free/mobile electrons
1
structure: giant
metallic
structure: giant
covalent
3
or ‘ ions with a sea of electrons’ for giant mark
C
conducts by delocalised/free/mobile electrons
with layers
N
4
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]
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52
110. (i)
(ii)
(iii)
Energy change when each atom in 1 mole
of gaseous atoms
loses an electron
(to form 1 mole of gaseous 1 ions).
3
increasing nuclear charge/number of protons
electrons experience greater attraction or pull / atomic
radius decreases / electrons added to same shell /same or
similar shielding
2
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 another
molecule/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 dipoledipole interactions / forces between the molecules
[6]
112. 1s22s22p63s23p63d24s2
[1]
113. (i)
+ - + - +
- + -
positive ions
(ii)
electrons move
electrons
+ - +
+ -
+
- +
+
-
(must be labelled)
2
1
[3]
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114. simple molecular
2
[2]
115. (i)
First
ionisation (energy)
Ra(g)  Ra+(g)  e−
1 mark for equation
1 mark for state symbols
‘‘ not required on ‘e’
(ii)
2
2
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)
(ii)
Cl2  2I−  I2  2Cl−
1 mark for species.
1 mark for balancing
Cl atom is smaller/has less shells
electron to be captured will be attracted more
2
2
[4]
117. (i)
(ii)
H bonding from O of 1 H2O molecule to H of another
dipoles shown
with lone pair involved in bond
3
Two properties from:
Ice is lighter than water/ max density at 4C
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]
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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 p
sub-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 electrons
for 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]
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122. (i)
molecule shown as non-linear
angle: 104 - 105
molecule shown as linear
(ii)
4
angle: 180
shape of H2O
shape of CO2
Electron pairs repel/groups (or regions) of electrons
repel/electron pairs get as far apart as possible
2
Oxygen in water surrounded by 4 areas of electron
density/2 bonds and 2 lone pairs
AND
Carbon in CO2 surrounded by 2 regions of electron
density/2 double bonds
[6]
123. (i)
(ii)
Attraction of electrons
in a bond
towards an atom
CO2 is symmetrical/H2O is not symmetrical
In CO2, dipoles cancel/in H2O, the dipoles don’t cancel
2
2
[4]
124. (a)
Energy change when each atom in 1 mole
of gaseous atoms
loses an electron
(b)
3
(to form 1 mole of gaseous 1 ions).
increasing nuclear charge/number of protons
electrons experience greater attraction or pull/atomic
radius decreases/electrons added to same shell/same or
similar shielding
2
[5]
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125. (i)
–
+
–
–
–
–
+
–
–
–
+
–
+–+–+ –+
–
– –
–
+ –+ – +
–
–
(ii)
–
positive ions/cations
and negative electrons
Can be described in words only for both marks
2
contain free/mobile/delocalised electrons
1
[3]
126. (i)
(ii)
shared pair of electrons
i.e. ‘shared electrons’ is worth 1 mark. Pair of electrons for
second mark
2
correct dot-and cross diagram
1
[3]
127. (i)
(ii)
(iii)
(iv)
electrostatic attraction
between oppositely charged ions
(charged or electrostatic for 1st mark)
correct dot-and cross diagram
correct charges
Mg

Mg2+  2e−
F2  2e− 
2F−
–sign not required with electron
solid: ions cannot move /in fixed positions in lattice
solution: ions are free to move
2
2
2
2
[8]
128. H2O
H bonding from O of 1 molecule to H of another
dipoles shown or described
with lone pair of O involved in the bond
3
CH4
van der Waals’ forces from oscillating dipoles/ temporary
dipoles/ transient dipoles/ instantaneous dipoles
leading to induced dipoles
caused by uneven distribution of electrons
3
[6]
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57
129. Two properties from:
Ice is less dense/lighter than water/floats on water/ max density
at 4C
explanation:
H bonds hold H2O molecules apart
/ open lattice in ice
/ H-bonds are longer
Higher melting/boiling point than expected
Not just high
Accept: ‘unusually high/strangely high/relatively high’
explanation: H bonds need to be broken
must imply that intermolecular bonds are broken
2
2
High surface tension
explanation
strength of H bonds across surface
mark 2 properties only  4 max
QoWC over whole question
 legible text with accurate spelling, punctuation
and grammar
1
[5]
130. Xe has a bigger atomic radius OR Xe has more shells
ALLOW Xe has more energy levels
ALLOW Xe has electrons in higher energy level
ALLOW Xe has electrons further from nucleus
IGNORE Xe has more orbitals OR more sub-shells
DO NOT ALLOW ‘different shell’ or ‘new shell’
Xe has more shielding
ALLOW More screening
There 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 decreases
OR 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 pull
IGNORE Xe has less effective nuclear charge
DO NOT ALLOW nuclear charge for nuclear attraction
[3]
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131. Advantage
removes or kills bacteria OR kills germs OR
kills micro-organisms OR make it safe to drink
OR sterilises water OR disinfects water
ALLOW to make water potable
IGNORE virus
IGNORE ‘purifies water’
DO NOT ALLOW ‘antiseptic’
Disadvantage
it is toxic OR poisonous OR could form chlorinated hydrocarbons
ALLOW forms carcinogens OR forms toxins
IGNORE harmful
DO 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 symbols
ALLOW 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 same
DO NOT ALLOW disproportional OR disproportionate OR
disproportion
1
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59
(ii)
Cl2 + 2NaOH → NaClO + NaCl + H2O
ALLOW multiples for either equation
3Cl2 + 6NaOH → NaClO3 + 5NaCl + 3H2O
ALLOW 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 number
OR
Neither would show properties OR trends of rest of group
OR
Neither would show properties OR trends of rest of period
OR
They are arranged by electron configuration
ALLOW any correct property difference
e.g. This would place a reactive metal in the same group as noble
gases
ALLOW they do not fit in with the rest of the group
1
[2]
136. (i)
2Mg + O2 → 2MgO
ALLOW multiples. Correct species must be seen
IGNORE state symbols
1
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(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 reacts
IGNORE temperature change
IGNORE steam produced
2
(iii)
Quicker OR more vigorous OR gets hotter
MUST 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-white
DO NOT ALLOW creamy white precipitate
ALLOW milky white precipitate
1
(ii)
Ag+(aq) + Cl–(aq) → AgCl(s)
Balanced equation correct
ALL state symbols correct
ALLOW 2 marks
AgNO3(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 THESE
balanced equation ONLY:
Ag2+(aq) + 2Cl–(aq) → AgCl2(s)
Ag(aq) + Cl(aq) → AgCl(s)
2
(iii)
(precipitate) dissolves OR disappears OR goes
colourless OR goes clear
ALLOW forms a solution
1
(b)
(i)
removes or kills bacteria OR kills germs OR
kills micro-organisms OR make it safe to drink OR
sterilises water
ALLOW to make water potable
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IGNORE virus
DO NOT ALLOW ‘purifies water’
DO NOT ALLOW ‘antiseptic’
1
(ii)
it is toxic OR poisonous OR could form chlorinated
hydrocarbons
ALLOW forms carcinogens OR forms toxins
DO NOT ALLOW harmful
DO 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 reduced
OR
Its oxidation state has increased and decreased
it has been oxidised (from 0) to +1 AND
it has been reduced (from 0) to –1
(These two points together subsume the first marking
point)
ALLOW ‘chlorine’ OR ‘it’
DO NOT ALLOW chlorIDE
IF CORRECT OXIDATION STATES IN (i), ALLOW 2
marks for:
it is oxidised to form HClO
it is reduced to form HCl
2
(iii)
Cl2 + 2NaOH → NaClO + NaCl + H2O
IGNORE state symbols
1
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62
(d)
(i)
2ClO2 → Cl2 + 2O2
OR
ClO2 → ½Cl2 + O2
IGNORE state symbols
1
(ii)
divides each % by correct Ar:
1.20 42.0 56.8
:
:
i.e.
1.0 35.5 16.0
OR
1.20, 1.18, 3.55
HClO3
ALLOW 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 get
empirical formula but only if no over-rounding
ALLOW 2 marks for correct answer of HClO3
2
(iii)
the oxidation number of chlorine
ALLOW ‘the oxidation state of chlorine OR
oxidation number of chlorine is 5’
DO NOT ALLOW ‘it’ instead of ‘chlorine’
DO NOT ALLOW ‘the oxidation state OR number of
chlorIDE is 5’
1
[14]
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63
138. (a)
(i)
Magnesium ions have a greater charge
Magnesium has more
(delocalised OR outer) electrons
Magnesium has greater attraction between ions and
electrons OR has stronger metallic bonds
USE annotations with ticks, crosses, ecf, etc for this part.
ALLOW REVERSE ARGUMENT
e.g. sodium ions have a smaller charge
ALLOW Mg2+ / Mg ion / Na ion / Na+ ion
ALLOW ‘charge density’ as alternative to ‘charge’
ALLOW REVERSE ARGUMENT
e.g. sodium has fewer electrons
ALLOW REVERSE ARGUMENT
e.g. sodium has less attractions between ions and
electrons
OR has weaker metallic bonds
3
(ii)
Cl2 OR S8 has intermolecular OR van der Waals’ forces
S8 has stronger intermolecular forces OR van der
Waals’ forces than Cl2
OR
S8 has more electrons
ALLOW REVERSE ARGUMENT ie Cl2 has weaker
intermolecular forces OR van der Waals’ forces
DO NOT ALLOW comparison involving covalent bonds
ALLOW REVERSE ARGUMENT
Cl2 has fewer electrons
2
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(b)
nuclear charge increases/ protons increase
electrons added to the same shell
OR
screening OR shielding remains the same
greater attraction OR greater pull
USE annotations with ticks, crosses, ecf, etc for
this part.
Nuclear OR proton(s) OR nucleus spelt correctly
ONCE
IGNORE ‘atomic number increases’
IGNORE ‘nucleus gets bigger’
‘charge increases’ is not sufficient
ALLOW ‘effective nuclear charge increases’ OR
‘shielded nuclear charge increases’
IGNORE reference to atomic radius staying the same
ALLOW shielding is similar
DO NOT ALLOW extra shielding
A 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)
0.11
137 .3
mark is for the working out which MUST lead to the correct
answer of 8 × 10–4 up to calculator value
1
(ii)
19.2
OR
calculated answer to (b)(i) × 24000
ALLOW 19 up to calculator value.
1
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(iii)
8.0 × 10–3
OR
calculated answer to (b)(i) × 10
ALLOW 8.01 × 10–3 up to calculator value
1
(iv)
any pH > 7 but <15
ALLOW a correct range of pH.
1
(c)
Less barium to react OR
some barium has already reacted
ALLOW less volume because contains some BaO or Ba3N2
1
(d)
reactivity increases (down the group)
atomic radii increase OR
there are more shells
there is more shielding OR more screening
the nuclear attraction decreases OR
Increased shielding and distance outweigh the
increased nuclear charge
easier to remove (outer) electrons OR
ionisation energy decreases
USE annotations with ticks, crosses, ecf, etc for
this part.
DO NOT ALLOW more orbitals OR more sub-shells
‘More’ is essential
ALLOW ‘more electron repulsion from inner shells’
ALLOW ‘nuclear pull’
IGNORE any reference to ‘effective nuclear charge’
ALLOW easier to form positive ion
5
[12]
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140. CaCO3(s) → CaO(s) + CO2(g)
equation
state symbols
state symbols are dependent on correct formulae of CaCO3,
CaO and CO2
DO 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 increases
OR protons increase
electrons added to the same shell
OR
screening OR shielding remains the same
IGNORE ‘atomic number increases’
IGNORE ‘nucleus gets bigger’
‘charge increases’ is not sufficient
ALLOW ‘effective nuclear charge increases’ OR
‘shielded nuclear charge increases’
ALLOW shielding is similar
3
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(ii)
atomic radii increase OR
there are more shells
there is more shielding OR more screening
the nuclear attraction decreases
OR
Increased shielding / distance outweigh the increased
nuclear charge
ALLOW electrons in higher energy level
ALLOW electrons are further from the nucleus
DO NOT ALLOW more orbitals OR more sub-shells
DO NOT ALLOW different shell or new shell
There 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 increase
OR
Down the group, more energy needed to break
intermolecular / van der Waals’ forces
electron(s) must be seen and spelt correctly ONCE
ALLOW number of electron shells increases
ALLOW iodine has most electrons
ALLOW chlorine has the least electrons
For ‘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-brown
IGNORE precipitate
1
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(ii)
iodine and (potassium) chloride
Cl2 + 2I– → I2 + 2Cl–
DO NOT ALLOW formulae (i.e. names essential)
ALLOW any correct multiple including fractions
IGNORE state symbols
2
(iii)
chlorine / Cl2 is more reactive (than iodine)
OR
chlorine / Cl2 is a more powerful oxidising agent
ALLOW chlorine is better at electron capture OR chlorine
attracts electrons more
ALLOW iodine is less reactive (than chlorine)
ALLOW iodide (ion) / I– is a stronger reducing agent
DO NOT ALLOW Cl is more reactive
DO NOT ALLOW explanation in terms of displacement
DO 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)
(ii)
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 reactivity
order of chlorine > bromine > iodine has been stated.
3
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]
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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)
(ii)
because Ca has changed from 0 to +2 (1)
and H has changed from +1 to 0 (1)
2
Calcium reacts with water producing
hydrogen/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 the
factors above/
less attraction/ held less tightly
[3]
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151. (a)
3
element
structure
bonding
Mg
giant
metallic

Si
giant
covalent

S
simple
covalent

1 mark for each correct row
(b)
(c)
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
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]
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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 is
clear.
1
[7]
153. (a)
add AgNO3 /add Ag+
ignore ammonia
white (precipitate)/goes white/precipitate that dissolves in
dilute NH3(aq)
3
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]
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154. number of electrons
/electron shells increases down group
van der Waals’ forces
/induced dipoledipole 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+
(ignore electrons: any mention of ‘neutrons’ is wrong)
1
(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
attraction increases/pull increases
(iv)
3
…….ORA
smaller
shell has been lost/less shielding/less electron
repulsion/proton : electron ratio larger
mark separately
2
[7]
156. (i)
(ii)
loss (of electrons)
1
Ba
0  ()2
2
(accept 2)
[3]
157. (i)
(ii)
MgO has reacted with CO2
Solid dissolves / disappears
Fizzing / bubbles
MgO  2HCl  MgCl2  H2O
MgCO3  2HCl  MgCl2  CO2  H2O
both reactions form magnesium chloride/MgCl2
1
2
3
[6]
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158. (i)
goes yellow/orange/brown
1
(ii)
Cl2  2Br–  Br2  2Cl–
OR
Cl2  2KBr  Br2  2KCl
1 mark for species.
1 mark for balancing
2
An electron is being gained
Cl atoms are smaller/less shells (ora)
In Cl, attraction for electrons is greater
3
(iii)
[6]
159. (a)
(i)
(ii)
(iii)
(iv)
(b)
Amount of substance that has the same number of
particles as there are atoms in 12 g of 12C/
6  1023/ Avogadro’s Number
0.275 120
moles =
= 0.0330 mol
1000
0.0330
moles Cl2 =
= 0.0165 mol
2
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.
bleach / disinfectant /sterilising /killing germs
NaClO3
1
1
2
1
1
[6]
160. (a)
Energy change when each atom in 1 mole
of gaseous atoms
loses an electron
(to form 1 mole of gaseous 1 ions).
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74
(b)
From Li  N, ionisation energy increases
number of protons/nuclear charge increases
nuclear attraction increases / shell drawn in by increased
nuclear charge/ atomic radius decreases
across period, electrons added to same shell
Not same subshell
From Be  B, ionisation energy decreases
for B, electron is removed from a p sub-shell/p
orbital/different sub-shell
which has a higher energy
watch for distinction between nuclear attraction and
nuclear charge in candidates’ scripts.
Also watch for confusion between shell and subshell.
Al
Sharp rise in successive ionisation energy between 3rd and
4th IE
marking a change to a new or different shell / there are 3
electrons in the outer shell
mention of ‘orbital’ or ‘sub-shell cancels ‘shell mark’ Each
marking point for Al is independent
QoWC:
7
3
links together two pieces of information
correctly within two of the sections below:
1. General trend across period
2. Be to B
Successive ionisation energies
[13]
161. (i)
hydrogen / H2
1
(ii)
Sr  2H2O  Sr(OH)2  H2
1
(iii)
different numbers of moles/atoms/ different Ar values
so different number of moles of H2 /more moles of Ca
(i.e. an attempt to quantify difference)
2
8 – 14
1
(iv)
[5]
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162. (i)
(ii)
(iii)
Ca+(g)  Ca2+(g)  e−
Equation with correct charges and 1 electron lost
state symbols
‘−’ not required on ‘e’
2
same number of protons or same nuclear charge attracting
less electrons/
electron removed from an ion/
less electron-electron repulsion (not less shielding)/
ion is smaller
1
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 nuclear
charge …..by at least one of the factors above
[6]
203.3 g mol−1
Accept 203
1
(ii)
white precipitate / goes white
1
(iii)
Ag+(aq)  Cl−(aq)  AgCl(s)
equation
state symbols
AgCl dissolves in NH3(aq)
163. (i)
(iv)
2
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]
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165. High boiling point or difficult to break linked to strong bonds in the right
context within Li or C
Li
conducts by delocalised/free/mobile electrons
1
structure: giant
metallic
structure: giant
covalent
3
or ‘ ions with a sea of electrons’ for giant mark
C
conducts by delocalised/free/mobile electrons
with layers
N
4
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
In CaCl2, oxidation state = 2
Oxidation number increases from Ca to CaCl2
2
[4]
168. (i)
(ii)
white precipitate/goes white
1
Ag  Cl–  AgCl
state symbols not required
1
[2]
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169. (i)
(ii)
(iii)
moles HCl = 2.0  50/1000 = 0.10
moles Ca = ½  moles HCl = 0.050
mass Ca = 40.1  0.050 = 2.00 g / 2.005 g
(accept 40  0.050 = 2.0 g)
(mass Ca of 4.0 g would score 1 mark as ‘ecf’ as molar ratio
has not been identified)
1
2
Ca has reacted with water
Ca  2H2O  Ca(OH)2  H2
state symbols not required
1st mark for H2
2nd mark is for the rest of the balanced equation
3
[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]
171. (i)
(ii)
(iii)
Energy change when each atom in 1 mole
of gaseous atoms
loses an electron
(to form 1 mole of gaseous 1 ions).
3
increasing nuclear charge/number of protons
electrons experience greater attraction or pull / atomic
radius decreases / electrons added to same shell /same or
similar shielding
2
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]
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172. uneven distribution of electrons
instantaneous /oscillating/changing/temporary/transient/
dipole on one atom
causes an induced/resultant dipole on another
molecule/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 dipoledipole 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 Br2
AND Br2 is stronger oxidising agent than I2 /
5
Cl2 has greater attraction for electrons than Br2
AND Br2 has greater attraction for electrons than I2
QoWC: At least two sentences that show legible text with
accurate spelling, punctuation and grammar so that the
meaning is clear.
(Mark this from anywhere within Q4)
1
[6]
174. (a)
RaCl2
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(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)
(ii)
effervescence/bubbles
Ra disappears/dissolves
2
8-14
1
[3]
176. (i)
First
ionisation (energy)
Ra(g)  Ra+(g)  e−
1 mark for equation
1 mark for state symbols
‘‘ not required on ‘e’
(ii)
2
2
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 (in
forming NaCl)/disproportionation
Cl reduces Cl to form NaCl AND Cl oxidises Cl in forming
NaOCl
[3]
179. (i)
Cl2  2I−  I2  2Cl−
1 mark for species.
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80
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 nuclear
charge in candidates’ scripts.
QoWC:
links together two statements in at least two of
the sections (a)(ii), (b) and (c)
[4]
181. (a)
Energy change when each atom in 1 mole
of gaseous atoms
loses an electron
(b)
3
(to form 1 mole of gaseous 1 ions).
increasing nuclear charge/number of protons
electrons experience greater attraction or pull/atomic
radius decreases/electrons added to same shell/same or
similar 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 /
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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
1
(iv)
0.00500  1000/200 = 0.0250 mol dm−3
(accept 120 cm3)
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
(iv)
98% waste produced which must be disposing of /made
into something worthwhile/CO2 being removed by
something sensible/
any sensible comment
3
1
[6]
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186. Physical states of halogens
chlorine 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)
Displacement
with 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
4
Quality of written communication

organise relevant information clearly and
coherently, using specialist vocabulary when
appropriate;
Evidence should link together two of the marking points:
e.g. size of the intermolecular forces linked to
temperature at which a substance changes state /
number of electrons linked to magnitude of intermolecular
forces/amount of energy needed to overcome forces
order of reactivity linked to observation
1
The key is a ‘because’ or ‘therefore’: i.e bromine doesn’t
displace chlorine because it is less reactive.
Greater intermolecular forces: therefore more energy needed to break them.
[9]
187. (a)
(b)
NaClO, oxidation state = 1
NaCl, oxidation state = −1
OR
Oxidation number decreases from NaClO  NaCl
by 2
2
(i)
84/24000 = 3. 5  10−3 mol
1
(ii)
3.5  10−3 mol
ans to (i)
1
(iii)
3.5  10−3  1000/5 = 0.70 mol dm−3
ans to (ii) x 1000/5
1
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(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 opposite
argument if ans < 4.5%
OR
molar 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 than
answer to (b)(iii) and therefore label is correct.
response depends upon answer to (b)(iii). Could be opposite
argument if ans 0.604
(d)
2HCl  NaClO  Cl2  NaCl  H2O
Award one mark for:
HCl  NaClO  Cl2  NaOH
2
[10]
188. (i)
(ii)
Answer is inclusive of 9  14 inclusive
Ca(s):
1s22s22p63s23p64s2
Ca(OH)2(aq):
1s22s22p63s23p6
1
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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