Chemistry 12 HL
Exam Prep / Topics 3 and 13
Periodicity Practice Questions
1.
Which factors lead to an element having a low value of first ionization energy?
I.
large atomic radius
II.
high number of occupied energy levels
III.
high nuclear charge
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
2.
Which equation represents the third ionization energy of an element M?
+
4+
2+
3+
–
A. M (g)  M (g) + 3e
B.
M (g)  M (g) + e
3+
–
3+
4+
–
C. M(g)  M (g) + 3e
D.
M (g)  M (g) + e
3.
The following table shows values that appear in the Data Booklet.
Table 1 Covalent (atomic) radii /10
Na
186
Mg
160
Table 2 Ionic radii/10
+
Na
98
Al
143
–12
–12
m
Si
117
N
70
P
110
0
66
S
104
F
58
Cl
99
4+
Si
42
3–
N
171
3–
P
212
2–
O
146
2–
S
190
–
F
133
–
Cl
181
m
2+
Mg
65
3+
Al
45
Explain why
(i) the magnesium ion is much smaller than the magnesium atom.
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(2)
(ii) there is a large increase in ionic radius from silicon to phosphorus.
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(2)
+
–
(iii) the ionic radius of Na is less than that of F .
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(2)
Chemistry 12 HL
4.
Exam Prep / Topics 3 and 13
2+
Define the term ligand. Cu (aq) reacts with ammonia to form the complex ion
2+
[Cu(NH3)4] . Explain this reaction in terms of an acid-base theory, and outline the bonding
2+
in the complex ion formed between Cu and NH3.
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(Total 4 marks)
5.
(a) (i)
State the meaning of the term electronegativity and explain why the noble gases
are not assigned electronegativity values.
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(2)
Chemistry 12 HL
(ii)
Exam Prep / Topics 3 and 13
State and explain the trend in electronegativity across period 3 from Na to Cl.
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(2)
(iii)
–
Explain why Cl2 rather than Br2 would react more vigorously with a solution of I .
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(2)
(b) State the acid-base properties of the following period 3 oxides.
MgO
Al2O3
P4O 6
Write equations to demonstrate the acid-base properties of each compound.
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(7)
(Total 13 marks)
Chemistry 12 HL
6.
Exam Prep / Topics 3 and 13
By reference to the structure and bonding in NaCl and SiCl4:
(i) State and explain the differences in electrical conductivity in the liquid state.
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(3)
(ii)
Predict an approximate pH value for the solutions formed by adding each compound
separately to water. Explain your answer.
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(4)
(Total 7 marks)
7.
Consider the transition metal complex, K3[Fe(CN)6].
(i)
Define the term ligand, and identify the ligand in this complex.
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(1)
(ii) Write the full electron configuration and draw the orbital box diagram of iron in its oxidation state
in this complex, and hence, determine the number of unpaired electrons in this state.
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(3)
Chemistry 12 HL
Exam Prep / Topics 3 and 13
(iii) Explain why many transition metal d-block complexes are coloured.
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(3)
(Total 7 marks)
8.
This question is about Period 3 elements and their compounds.
(a) Explain, in terms of their structure and bonding, why the element sulfur is a nonconductor of electricity and aluminium is a good conductor of electricity.
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(4)
(b) Explain, in terms of its structure and bonding, why silicon dioxide, SiO2, has a high
melting point.
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(2)
(Total 6 marks)
Chemistry 12 HL
Exam Prep / Topics 3 and 13
MARK SCHEME
1.
A
2.
B
3.
(i)
(ii)
loss of 2 electrons/outer electrons;
3 shells to 2;
net attractive force increases;
max
P
4+
has one more shell than Si ;
some justification in terms of electron loss/gain;
net attractive forces;
2
3–
(iii) same electron arrangement/both have two complete shells;
+
extra protons in Na (attract the electrons more strongly);
2 max
2
[6]
4.
ligand: a molecule or ion that can bond to a (central) metal ion
(to form a complex);
2+
NH3: Lewis base and Cu : Lewis acid (need both for mark);
2+
each NH3/ligand donates an electron pair (to Cu );
forming coordinate covalent/dative covalent bond;
4
[4]
5.
(a) (i)
(ii)
(iii)
the ability of an atom to attract a bonding pair of electrons;
inert/do not react/do not attract electrons/stable electron
configuration/full outer electron shell/do not form bonds;
electronegativity increases (along period 3 from Na to Cl);
number of protons increases/nuclear charge increase/core charge
increase/size of atom decreases;
Do not accept “greater nuclear attraction”.
Cl2 stronger oxidising agent;
Cl2 has greater attraction for electrons/has a higher electron affinity;
Accept converse statements for Br2.
2
2
2
(b) MgO - basic oxide/alkali;
MgO + 2HCl ® MgCl2 + H2O/MgO + H2O ® Mg(OH)2;
Al2O3 - amphoteric oxide/acidic and basic oxide;
Al2O3 + 6HCl ® 2AlCl3 + 3H2O;
–
–
Al2O3 + 2OH + 3H2O ® 2Al(OH)4 /Al2O3 + 2OH ® 2AlO2 + H2O;
P4O6 - acidic oxide;
P4O6 + 6H2O ® 4H3PO3;
All equations must be balanced.
7
[13]
Chemistry 12 HL
6.
(i)
(ii)
Exam Prep / Topics 3 and 13
NaCl conducts and SiCl4 does not;
NaCl ionic and SiCl4 covalent;
ions can move in liquid (in NaCl);
3
NaCl pH = 7;
+
−
salt of strong acid and strong base/Na and Cl not hydrolysed;
SiCl4 pH = 0 to 3;
HCl is formed/strong acid formed;
4
[7]
7.
(i)
(ii)
an ion or molecule, with a lone pair of electrons that coordinates to a metal
−
atom or to a metal ion to form a complex/(OWTTE) and cyanide/CN ;
Fe
3+
1
2
2
6
2
6
5
= 1s , 2s , 2p , 3s , 3p , 3d ;
[Ar]
-
-
3d
-
-
;
5
5 unpaired electrons;
3
(iii) presence of unpaired electrons;
the d orbitals are split into two energy levels;
electrons move between these energy levels;
absorb energy from light of visible wavelength/OWTTE;
max
Award [1] each for any three.
3
[7]
8.
(a) sulfur is (simple) molecular;
(contains) covalent bonds/no delocalized electrons/all (outer) electrons used
in bonding;
aluminium contains positive ions and delocalized electrons;
(delocalized) electrons move (when voltage applied or current flows);
(b) silicon dioxide is macromolecular/giant covalent;
many/strong covalent bonds must be broken;
Award max [1] if no mention of covalent.
Do not accept weakened instead of broken.
4
2
[6]