Dr. Vikram Panchal
WORKSHEET-1 SEM-3 [JEE / NEET]
Radius ratio
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Silver metal crystallizes in a cubic closest packed arrangement with the edge of
the unit cell having a length a=407pm. What is the radius of silver atom?
The length of the unit cell of a bcc lattice metal is 352pm. Calculate radius of the
atom of the metal.
Sodium metal crystallises in body-centred cubic lattice with cell edge 4.29Ao .
What is the radius of sodium atom?
CsCl crystallises in a cubic lattice that has a Cl- at each corner and Cs+ at the
centre of the unit cell. If rCs+ is 1.69Ao and rCl- is 1.81Ao. what is the value of edge
length (a) of the cube?
Aluminium crystallises in a cubic closed packed structure. Its metallic radius is
125pm. (1) what is the length of the side of the unit cell?
(2) How many unit cells are there in 1cm3 of aluminium?
Copper metal has a face centred cubic structure with the unit-cell length equal to
0.361nm. picturing copper ions in contact along the face diagonal, what is the
apparent radius of a copper ion?
A metal crystallises in a simple cubic unit cell. The length of the edge of the unit
cell, a, is 6.22Ao. find the radius of each atom of the metal.
The radius of copper atom is 128pm. If it crystallises in a face centred cubic
lattice (fcc). What will be the length of the edge of the unit cell?
Gold has a close-packed structure which can be viewed as spheres occupying
0.74 of the volume. If the density of gold is 19.3g/cc, calculate the apparent
radius of gold in the solid. (Au=197amu).
Ionic radii of cations & anions and Defects
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Sem-3
Predict the structure of MgO crystal and the co-ordination no. of the cation in which the
radii of the cation and anion are 65pm and 140pm respectively.
An ionic solid AB has NaCl structure. If radius is A+ is 100pm, what will be expected
radius of anion?
A solid A+B- has NaCl type close packed structure. If the anion has the radius of 250pm,
what should be the radius of cation? Can a cation ‘c’ having radius of 180pm be slipped
into the tetrahedral site of the crystal A+B- ?
The composition of a sample of wustite is Fe0.93O1.00. What % of the iron is present in the
form of Fe(III)?
Analysis shows that a metal oxide has the empirical formula M0.96 O1.00. Calculate the % of
M+2 and M+3 ions in the sample.
If NaCl is dopped with 10-3 mol% of SrCl2, Calculate the concentration of cation vacancies.
Ferric oxide crystallises in a hexagonal close packed array of oxide ion with two out of
every three octahedral holes occupied by ferric ions. Derive the formula of ferric oxide.
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