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SECTION A
QUESTION 1 Answer all parts (This question is worth 10 marks)
(a) The colour in stained-glass windows often comes from metal
nanoparticles inside the silica glass. Archaeologists took a small sample
from an old window, and analysed it under a microscope to produce the
images shown above.
(i) Suggest what type of microscope they are using, and explain your
reasoning.
[2 marks]
(ii) Explain why the nanoparticles appear darker than their
surroundings.
[2 marks]
(iii) Suggest a technique that could be used on the metallic
nanoparticles in conjunction with the microscope, and how it would
allow identification of the metal element.
[2 marks]
(b) The glass was made predominantly from three components: quartz,
Na2CO3, and CaO.
Explain the function of each component. How would you expect the
silica in the original quartz to differ from the final glass of the window in
terms of structural order
[4 marks]
PAPER CODE CHEM313 page 3 of 11 CONTINUED
SECTION B
QUESTION 2 Answer all parts (This question is worth 30 marks)
(a) The powder X-ray diffraction data (PXRD) pattern below (l = 1.5406 )
was measured for a sample of a caesium halide compound CsX (where
X is an unknown halide ion) that adopts a cubic crystal structure.
(i) Using the ionic radii given, predict the structure types for caesium
fluoride CsF and caesium iodide CsI.
Ionic radii: Cs+ 1.88 , F- 1.33 , I- 2.20 .
[4 marks]
(ii) Sketch a 3D representation of the CsI structure, describe the
coordination of the ions and its lattice type.
[5 marks]
(iii) Using the PXRD data, calculate the lattice parameter for the
structure and determine whether the sample is CsF or CsI.
[8 marks]
QUESTION 2 CONTINUES ON THE NEXT PAGE
2q / degrees sin2 q
25.56 0.04892
29.60 0.06523
42.35 0.13046
50.12 0.17939
52.51 0.19569
61.44 0.26093
67.65 0.30985
69.65 0.32616
PAPER CODE CHEM313 page 4 of 11 CONTINUED
(b) Zeolites are microporous crystalline aluminosilicates with the general
formula Mx/n[(AlO2)x(SiO2)y]·mH2O.
(i) Explain how the structure and chemistry of zeolites enables their
use in size or shape-selective acid catalysis.
[5 marks]
(ii) Describe two methods to chemically modify the small pore Zeolite A
Na12[(AlO2)12(SiO2)12]·27H2O to tune its properties for separating
long chain hydrocarbons from branched and cyclic hydrocarbons.
[8 marks]
PAPER CODE CHEM313 page 5 of 11 CONTINUED
QUESTION 3 Answer all parts (This question is worth 30 marks)
(a) A 3D representation of the crystal structure adopted by a metal sulfide
compound is shown below. Its cubic unit cell was determined to have
unit cell length of a = 5.722
(i) Describe the coordination of the ions and determine the
stoichiometry of the compound.
[4 marks]
(ii) Calculate the spacing of the (111) lattice planes d111 and the
position of the reflection in powder X-ray diffraction pattern
(l = 1.5406 ) of the compound.
[3 marks]
(iii) Identify the lattice centring of the structure shown. Using the
structure factor equation given, show that the (110) reflection is
systematically absent for the structure shown. Note: The cations
can be disregarded for this purpose.
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[6 marks]
QUESTION 3 CONTINUES ON THE NEXT PAGE
sulfide
metal cation
x
y
z
PAPER CODE CHEM313 page 6 of 11 CONTINUED
(b) Strontium titanate SrTiO3 adopts a cubic perovskite structure at 293 K.
It undergoes a structural phase transition to a tetragonal perovskite
below 100 K. Pair distribution functions (PDF) of SrTiO3 measured
above and below the transition temperature are shown below for the
Ti–O region.
(i) Sketch a 2D representation of the perovskite structure with the B
cation at the centre of the unit cell.
[2 marks]
(ii) Describe the PDF method and account for the differences observed
in the PDFs at the two temperatures.
[10 marks]
(iii) Predict whether doping SrTiO3 with Nb2O5 results in formation of a
solid doped on the A or B site, and list the possible types and
numbers of defects formed. Assume that niobium is present as Nb5+
in the structure.
[5 marks]
PAPER CODE CHEM313 page 7 of 11 CONTINUED
SECTION C
QUESTION 4 Answer all parts (This question is worth 30 marks)
(a) The probability of an electron occupying a level with energy E in the
band structure of a solid is given by the Fermi-Dirac distribution, f(E).
Define the term EF in the equation above and briefly describe its
physical meaning. Sketch graphs to show how f(E) varies with E at 0 K
and 300 K, labelling clearly EF.
( ) =
1 + exp =

1
%
B & C
[7 marks]
(b) Bi2S3 is a semiconductor with a band gap, Eg, of 1.3 eV. The
temperature dependence of the conductivity of Bi2S3 is described by
the Arrhenius expression:
= ‘ exp E (
2 &
F
(i) Explain what is meant by a band gap including a sketch of the band
structure of an intrinsic semiconductor.
[3 marks]
(ii) At 300 K, Sb2S3 has a conductivity of 0.31 × 10–5 S m–1
. Calculate
the conductivity expected at 200 K and comment on your answer.
Note that kB = 8.617 × 10–5 eV K–1
.
[4 marks]
(iii) Most samples with the nominal formula Bi2S3 are slightly deficient in
sulfur. Explain how this affects the electronic properties.
[3 marks]
(iv)Predict whether Bi2Se3 will have a smaller or larger band gap than
Bi2S3 and explain your answer.
[3 marks]
QUESTION 4 CONTINUES ON THE NEXT PAGE
PAPER CODE CHEM313 page 8 of 11 CONTINUED
(c) YBa2Cu3O7–δ shows a wide range of properties depending on the value
of delta d. Explain what the three transitions (labeled 1 to 3) are in the
phase diagram below and describe what experiments you would
conduct to measure them.
[10 marks]
PAPER CODE CHEM313 page 9 of 11 CONTINUED
QUESTION 5 Answer all parts (This question is worth 30 marks)
(a) State what is meant by superexchange and predict the type of
superexchange expected across a linear 180° and a 90° M–O–M
linkage. Include in your answer a sketch of the relevant superexchange
pathway and the expected sign of the exchange constant, Jex.
[6 marks]
(b) For the following compounds state the expected magnetic ordering and
identify the superexchange pathways:
(i) VO with the NaCl type structure.
[3 marks]
(ii) LaCrO3 with the perovskite structure. In addition, would you expect
it to have a higher or lower ordering temperature than LaFeO3
[3 marks]
(iii) The hypothetical ordered perovskite La2CrIIIFeIIIO6.
[3 marks]
(c) The doped manganite perovskite La0.65Sr0.35MnO3 orders
ferromagnetically and is metallic below a Curie temperature of
TC = 360 K.
(i) Discuss, with diagrams, the magnetic exchange interaction that
leads to these behaviours in doped manganite perovskites.
[5 marks]
(ii) Predict the value of the saturated magnetic moment in the
ferromagnetic phase of La0.65Sr0.35MnO3, and the value of its high temperature effective moment.
[4 marks]
(iii) Briefly explain why we can use neutron diffraction to observe
magnetic order in inorganic solids and describe how the low temperature powder neutron diffraction patterns of SrMnO3 and
La0.65Sr0.35MnO3 might differ.
[6 marks]
PAPER CODE CHEM313 page 10 of 11 CONTINUED
APPENDIX
Useful Constants
Gas constant: R = 8.314 J K 1 mol 1
Boltzmann constant: kB = 1.381 ′ 10 23 J K 1
Avogadro constant: NA = 6.022 ′ 1023 mol 1
Electron rest mass: me = 9.109 ′ 10 31 kg
Atomic mass constant: amu = 1.661 ′ 10 27 kg
Elementary charge: e = 1.602 ′ 10 19 C
Speed of light in vacuo: c = 2.998 ′ 108 m s 1
Planck constant: h = 6.626 ′ 10 34 J s
Pressure: 1 atm = 101325 Pa
PAPER CODE CHEM313 page 11 of 11 END
1 18
1 2
H He
Hydrogen Helium
1.008 2 13 14 15 16 17 4.00
3 4 5 6 7 8 9 10
Li Be B
C
N
O
F Ne
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
6.94 9.01 10.81 12.01 14.01 16.00 19.00 20.18
11 12 13 14 15 16 17 18
Na Mg Al Si P
S Cl Ar
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
22.99 24.31 3
4
5
6
7
8
9 10 11 12 26.98 28.09 30.97 32.06 35.45 39.95
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
39.10 40.08 44.96 47.90 50.94 52.01 54.94 55.85 58.93 58.69 63.54 65.37 69.72 72.59 74.92 78.96 79.91 83.80
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
85.47 87.62 88.91 91.22 92.91 95.94 98.91 101.07 102.91 106.4 107.87 112.40 114.82 118.71 121.75 127.60 126.90 131.30
55 56 57 58-71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Cesium Barium Lanthanum Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon
132.91 137.34 138.91 178.49 180.95 183.85 186.2 190.2 192.2 195.08 196.97 200.59 204.37 207.19 208.98 210 210 222
87 88 89 90-103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118
Fr Ra Ac Rf Uub Db Sg Bh Hs Mt Ds Rg Uuq Uuh Uuo
Francium Radium Actinium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadium Roentgenium Ununbium Ununquadrium Ununhexium Ununoctium
223 226.03 227.03 261 262 263 264 277 268 271 272
58 59 60 61 62 63 64 65 66 67 68 69 70 71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium
140.12 140.91 144.24 146.92 150.35 151.96 157.25 158.92 162.50 164.93 167.26 168.93 173.04 174.97
90 91 92 93 94 95 96 97 98 99 100 101 102 103
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium
232.04 231.04 238.03 237.05 239.05 241.06 244.07 249.08 252.08 252.09 257.10 258.10 259 262
The Periodic Table of the Elements