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Date May 2017 Marks available 1 Reference code 17M.2.hl.TZ1.2
Level HL Paper 2 Time zone TZ1
Command term Suggest Question number 2 Adapted from N/A

Question

Titanium and vanadium are consecutive elements in the first transition metal series.

TiC l 4 reacts with water and the resulting titanium(IV) oxide can be used as a smoke screen.

Describe the bonding in metals.

[2]
a.

Titanium exists as several isotopes. The mass spectrum of a sample of titanium gave the following data:

M17/4/CHEMI/HP2/ENG/TZ1/02.b

Calculate the relative atomic mass of titanium to two decimal places.

[2]
b.

State the number of protons, neutrons and electrons in the 22 48 Ti atom.

M17/4/CHEMI/HP2/ENG/TZ1/02.c

[1]
c.

State the full electron configuration of the 22 48 T i 2 + ion.

[1]
d.i.

Suggest why the melting point of vanadium is higher than that of titanium.

[1]
d.ii.

Sketch a graph of the first six successive ionization energies of vanadium on the axes provided.

M17/4/CHEMI/HP2/ENG/TZ1/02.d.iii

[1]
d.iii.

Explain why an aluminium-titanium alloy is harder than pure aluminium.

[2]
d.iv.

Describe, in terms of the electrons involved, how the bond between a ligand and a central metal ion is formed.

[1]
e.

Outline why transition metals form coloured compounds.

[4]
f.

State the type of bonding in potassium chloride which melts at 1043 K.

[1]
g.i.

A chloride of titanium, TiC l 4 , melts at 248 K. Suggest why the melting point is so much lower than that of KCl.

[1]
g.ii.

Formulate an equation for this reaction.

[2]
h.i.

Suggest one disadvantage of using this smoke in an enclosed space.

[1]
h.ii.

Markscheme

electrostatic attraction

between «a lattice of» metal/positive ions/cations AND «a sea of» delocalized electrons

 

Accept “mobile electrons”.

Do not accept “metal atoms/nuclei”.

[2 marks]

a.

( 46 × 7.98 )  +  ( 47 × 7.32 )  +  ( 48 × 73.99 )  +  ( 49 × 5.46 )  +  ( 50 × 5.25 ) 100 = 47.93

 

Answer must have two decimal places with a value from 47.90 to 48.00.

Award [2] for correct final answer.

Award [0] for 47.87 (data booklet value).

[2 marks]

b.

Protons: 22 AND Neutrons: 26 AND Electrons: 22

[1 mark]

c.

1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 2

[1 mark]

d.i.

vanadium has smaller ionic radius «leading to stronger metallic bonding»

 

Accept vanadium has «one» more valence electron«s» «leading to stronger metallic bonding».

Accept “atomic” for “ionic”.

[1 mark]

d.ii.

regular increase for first five AND sharp increase to the 6th

 

A log graph is acceptable.

Accept log plot on given axes (without amendment of y-axis).

Award mark if gradient of 5 to 6 is greater than “best fit line” of 1 to 5.

[1 mark]

d.iii.

titanium atoms/ions distort the regular arrangement of atoms/ions

OR

titanium atoms/ions are a different size to aluminium «atoms/ions»

prevent layers sliding over each other

 

Accept diagram showing different sizes of atoms/ions.

[2 marks]

d.iv.

pair of electrons provided by the ligand

 

Do not accept “dative” or “coordinate bonding” alone.

[1 mark]

e.

partially filled d-orbitals

«ligands cause» d-orbitals «to» split

light is absorbed as electrons transit to a higher energy level «in d–d transitions»
OR
light is absorbed as electrons are promoted

energy gap corresponds to light in the visible region of the spectrum

colour observed is the complementary colour

[4 marks]

f.

ionic

OR

«electrostatic» attraction between oppositely charged ions

[1 mark]

g.i.

«simple» molecular structure

OR

weak«er» intermolecular bonds

OR

weak«er» bonds between molecules

 

Accept specific examples of weak bonds such as London/dispersion and van der Waals.

Do not accept “covalent”.

[1 mark]

g.ii.

TiC l 4 (l) + 2 H 2 O(l) Ti O 2 (s) + 4HCl(aq) correct products
correct balancing

 

Accept ionic equation.

Award M2 if products are HCl and a compound of Ti and O.

[2 marks]

h.i.

HCl causes breathing/respiratory problems

OR

HCl is an irritant

OR

HCl is toxic

OR

HCl has acidic vapour

OR

HCl is corrosive

 

Accept TiO2 causes breathing

problems/is an irritant.

Accept “harmful” for both HCl and TiO2.

Accept “smoke is asphyxiant”.

[1 mark]

h.ii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.i.
[N/A]
d.ii.
[N/A]
d.iii.
[N/A]
d.iv.
[N/A]
e.
[N/A]
f.
[N/A]
g.i.
[N/A]
g.ii.
[N/A]
h.i.
[N/A]
h.ii.

Syllabus sections

Core » Topic 3: Periodicity » 3.2 Periodic trends
Show 78 related questions
Core » Topic 4: Chemical bonding and structure » 4.5 Metallic bonding
Core » Topic 3: Periodicity
Core » Topic 4: Chemical bonding and structure
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