Structures of Simple Inorganic Solids
Dr S.J. Heyes
Problem Set from the 1st Year Inorganic Chemistry
Michaelmas Term 1999 / Hilary Term 2000
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- Draw a perspective sketch of a unit cell of
the cubic close-packed structure, consisting of spheres of only
- Indicate the orientation of the close-packed
layers in your diagram. What is the stacking sequence of
- Calculate the percentage of the total volume
which is occupied by spheres.
- Describe other crystal structures that can be
formed by the packing of equal spheres.
- Show by means of a sketch the positions of
octahedral and tetrahedral holes in a cubic close-packed
- Give examples of binary compounds which
exhibit structures where some or all of these octahedral and/or
tetrahedral holes are filled by another element.
Compare and contrast the structures of
the following pairs of solids. Include descriptions of the
structures and particularly discuss the reasons for their
(a) NaCl & CsCl.
(b) NiO & NiAs.
(d) ZnS (Zinc Blende) &
(e) C (Diamond) & C
- Differentiate clearly between the terms
lattice and crystal
- What structures might you expect the following
compounds to adopt. Give your reasons.
- Identify the formula units,
AnBm, and the structure type in each
- Give an example of another compound that
adopts each structure.
- State the coordination about A and B in each
- Explain how the "Radius Ratio Rules" may be
used to rationalize or predict the structures of simple ionic
- At room temperature and atmospheric pressure
all the alkali metal halides adopt the rock salt (NaCl) structure
except cesium compounds CsCl, CsBr and CsI. Comment on this in the
light of the following ionic radii:
- What changes would you expect on increase in
- The NiAs structure is shown in plan view
- Identify the coordination numbers and
geometries of Ni and As and show the coordination environment of
each on a plan diagram.
- If the structure is regarded as constructed of
NiAsx polyhedra, describe how
these polyhedra are linked together.
- The delafossite structure of
CuFeO2 is shown in the plan view
- Draw a perspective sketch of the unit cell
roughly to scale (remember that c = 6a) and show the
positions of the O and Cu ions. Hence identify the arrangement of
O ions around Cu ions.
- Using the same approach as for NiAs, identify
the arrangement of O ions around the Fe ion at (0,0,1/2). Show the
coordination of O around Fe on a plan diagram.
- With the aid of a plan diagram, demonstrate
that each O ion is surrounded by one Cu ion and three Fe ions in a
roughly tetrahedral arrangement.
- Describe how the
OCuFe3 tetrahedra are linked
together in the delafossite structure.
Solids Page Lecture1
Lecture 2 Lecture
3 Lecture 4 Problems
S.J. Heyes, Oxford, 1996-2000