Author: nashton
Company: RM plc

F321 module 3 Practice 1:

1.	(i)	They have different numbers of protons/
Ba has one more proton/Ba has 56 p^+; Cs has 55 p^+ 	1
(ignore electrons: any mention of ‘neutrons’ is wrong)
(ii)	s 	1
(iii)	Cs to Ba: nuclear charge increases/more protons 
electrons are in: the same shell/sub-shell/orbital
/similar shielding/same shielding 	3
attraction increases/pull increases 	…….ORA
(iv)	smaller 	2
shell has been lost/less shielding/less electron
repulsion/proton : electron ratio larger 
mark separately
[7]

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

3.	(i)	MgO has reacted with CO_2	1
(ii)	Solid dissolves / disappears
Fizzing / bubbles	2
MgO + 2HCl → MgCl_2 + H_2O
MgCO_3 + 2HCl → MgCl_2 + CO_2 + H_2O
both reactions form magnesium chloride/MgCl_2	3
[6]

4.	(i)	goes yellow/orange/brown 	1
(ii)	Cl_2 + 2Br^– → Br_2 + 2Cl^–
OR
	Cl_2 + 2KBr → Br_2 + 2KCl
	1 mark for species.
	1 mark for balancing	2
(iii)	An electron is being gained
	Cl atoms are smaller/less shells (ora) 
	In Cl, attraction for electrons is greater	3
[6]

5.	(a)	(i)	Amount of substance that has the same number of
	particles as there are atoms in 12 g of ^12C/
	6 × 10^23/ Avogadro’s Number	1
(ii)	moles =  = 0.0330 mol
	moles Cl_2 =  = 0.0165 mol	1
(iii)	volume Cl_2 = 0.0165 × 24000 = 396 cm^3 / 0.396 dm^3
	792 cm^3 worth 1 mark (no molar ratio)
	1584 cm^3 worth 1 mark (x 2)
	units needed.	2
(iv)	bleach / disinfectant /sterilising /killing germs	1
 
(b)	NaClO_3	1
[6]

6.	(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]

7.	(i)	hydrogen / H_2 	1
(ii)	Sr + 2H_2O → Sr(OH)_2 + H_2 	1
(iii)	different numbers of moles/atoms/ different A_r values
so different number of moles of H_2 /more moles of Ca
(i.e. an attempt to quantify difference)	2
(iv)	8 – 14 	1
[5]

8.	(i)	Ca^+(g) → Ca^2+(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]

9.	(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 NH_3(aq) 
(iv)	AgBr dissolves in conc NH_3(aq)/
partially soluble in NH_3(aq) 
AgI insoluble in NH_3(aq) 	3
[7]

10.	Cl_2: 0 
HOCl +1 
HCl −1 
[4]

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