1.	(i)	atoms of the same element with different numbers of
neutrons/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]

2.	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]

3.	(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	
85Rb	71 to 73	37	48	37	
87Rb	27 to 29	37	50	37	
mark	must add
up to 100
				
ie 1 mark for each atomic structure; 1 for % compositions.

= 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]

4.	(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]

5.	(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 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]

6.	(i)	mass = 0.0500 ´ 23.0 = 1.15 g 	1
(ii)	moles H2 = 0.0250 
volume H2 = 0.0250 ´ 24 = 0.600 dm3 	2
ecf from calculated moles H2
0.0500 mol in 50.0 cm3	1
(iii)	concentration = 0.0500 ´ 20 = 1.00 mol dm−3 
[4]

7.	(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]

8.	(i)	

		protons	neutrons	electrons
	25Mg	12	13	12	
26Mg	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]

9.	(i)	MgO has reacted with CO2	1
(ii)	Solid dissolves / disappears
Fizzing / bubbles	2
MgO + 2HCl ® MgCl2 + H2O
MgCO3 + 2HCl ® MgCl2 + CO2 + H2O
both reactions form magnesium chloride/MgCl2	3
[6]

10.	(i)	Oxidation state goes from 0 in O2 
® -2 in MgO 	2
(ii)	

or with Mg full shell.
correct dot and cross; correct charges	2
[4]

11.	(i)	dative covalent, bonded pair comes from same atom/	1
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
[2]

12.	(i)	203.3 g mol−1 	1
Accept 203
(ii)	white precipitate / goes white 	1
(iii)	Ag+(aq) + Cl−(aq) ® AgCl(s)
equation 
state symbols 	2
AgCl dissolves in NH3(aq) 
(iv)	AgBr dissolves in conc NH3(aq)/
partially soluble in NH3(aq) 
AgI insoluble in NH3(aq) 	3
[7]

13.  No mark scheme available

14.	isotope	protons	neutrons	electrons
nickel-58	28	30	28
nickel-60	28	32	28
nickel-62	28	34	28
	           	
For ecf, 3rd column same as first column.
[3]

15.	(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/ ammonium
nitrate/ urea/ refrigeration/ cleaning agents/ fertiliser
(if not allowed in (ii) (1)	1
[4]

16.	(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	3
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)
(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]

17.	(a)	(i)	Amount of substance that has the same number of
	particles as there are atoms in 12 g of 12C/
	6 ´ 1023/ Avogadro’s Number	1
(ii)	moles =  = 0.0330 mol
	moles Cl2 =  = 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]

18.	(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 =  / 121.8558 
= 121.9 	2
[5]

19.	(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]

20.	(i)

positive ions (1) electrons (1) (must be labelled)	2
(ii)	the electrons move (1)	1
[3]

21.	(i)	attraction between oppositely charged ions	1
(ii)

	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/water
molecules are uncharged (1)
MgCl2 conducts when aqueous because ions are free to move (1)	3
[6]

22.	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]

23.	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]

24.	(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 	2
N.B. H electron and Ca electrons can look the same.
[5]

25.	(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 
® d– on more electronegative atom and d+ on less	2
electronegative element in example 
May need to look for these marks below if not given here.
[4]

26.	(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]

27.	(i)	2Na(s) + Cl2(g) ® 2NaCl(s) 
1st mark for equation	2
2nd mark for state symbols
(ii)	Giant ionic (lattice) or 3D 
with alternating Na+ and Cl– 	2
[4]

28.	(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− 	2
1 mark for correct species; 1 mark for state symbols
No charge required on electron.
Ignore (g) on e
(iii)	Large difference between 6th and 7th IEs 	2
marking a different shell (closer to nucleus) 
allow ‘inner shells’/new shell/full shell/first shell
marking points independent.
not sub-shell or orbital
[7]

29.	(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]

30.	

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]

31.	(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]

32.	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
------------------------------------------- 
 
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 /	1
large 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/	2
graphite is non-polar 
QWC:	At least 2 complete sentences in which
the meaning is clear. 	1
[8]

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

(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	7
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	3
mention of ‘orbital’ or ‘sub-shell cancels ‘shell mark’ Each marking point for Al is independent
	QoWC:	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]

34.	(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 attracting
less 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 nuclear
charge …..by at least one of the factors above 
[6]

35.	High boiling point or difficult to break linked to strong bonds in the right
context 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]

36.	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]

37.	(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)	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
(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]

38.	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 dipole-
dipole interactions / forces between the molecules 
[6]

39.	(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/atomic
radius decreases/electrons added to same shell/same or
similar shielding 	2
[5]

40.	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 	2
Higher melting/boiling point than expected 
	Not just high
	Accept: ‘unusually high/strangely high/relatively high’
explanation: H bonds need to be broken 	2
	must 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, punctuation
	and grammar 
[5]

41.	(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]

42.	(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 reactivity
order of chlorine > bromine > iodine has been stated.	3
(ii)	Br2 + 2I– ® 2Br– + I2 (1)	1
[4]

43.	(a)	add AgNO3 /add Ag+ 	3
ignore ammonia
white (precipitate)/goes white/precipitate that dissolves in
dilute 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]

44.	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]

45.	(i)	loss (of electrons) 	1
(ii)	Ba 
0 ® (+)2  (accept 2+)	2
[3]

46.	(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
(iv)	8 – 14 	1
[5]

47.	Cl2: 0 
HOCl +1 
HCl −1 
[4]

48.	(a)	……Ca(s) + …..2  HCl(aq) …….CaCl2(aq) + .H2(g). 	2
(g) not required for H2
 
(b)	In Ca, oxidation state = 0  and	2
In CaCl2, oxidation state = +2 
Oxidation number increases from Ca to CaCl2
[4]

49.	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. 	1
(Mark this from anywhere within Q4)
[6]

50.	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]

51.	(i)	Cl2 + 2I− ® I2 + 2Cl− 	2
1 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]

52.	(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]

53.	(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]

54.	Strontium reacts with oxygen/strontium oxide forms/SrO
forms 
2Sr + O2 ® 2SrO /
Sr + ½ O2 ® SrO 
[2]

55.	(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 /made
into something worthwhile/CO2 being removed by
something sensible/	1
any sensible comment 
[6]

56.	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) 	4
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
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]

57.	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]