Advertisements
Advertisements
Question
With the help of a labelled diagram show that there are four octahedral voids per unit cell in a cubic close packed structure.
Advertisements
Solution
In ccp, each cube consists of eight cubic components, number of atoms per unit cell in ccp is
Where Nc = No. of atoms at corner
Nf = No. of atoms at face centre
= Nc × Nf × contribution
= `8 xx 1/8 + 6 xx 1/2` = 4
Position of octahedral voids = Edge centre and body centre
Number of actahedral voids per unit cell in cubic close packing = `N_e xx 1/4 + N_b xx 1`
= `12 xx 1/4 + 1 xx 1` = 4
⇒ Number of octahedral voids = 4.
APPEARS IN
RELATED QUESTIONS
A compound forms hexagonal close-packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?
Ferric oxide crystallises in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.
Aluminium crystallises in a cubic close-packed structure. Its metallic radius is 125 pm.
- What is the length of the side of the unit cell?
- How many unit cells are there in 1.00 cm3 of aluminium?
The coordination number of AB having rock salt geometry is ____________.
Hexagonal close packed arrangement of ions is described as ____________.
What is the coordination number in a square close packed structure in two dimensions?
Which of the following statement is not true about the hexagonal close packing?
How can you best describe the elongated octahedral structure of blue vitriol, CuSO4.5H2O?
In the SF4 molecule, there are:
The octane number of Iso-octane is
The crystal system of a compound with unit cell dimensions a = 0.387, b = 0.387 and c = 0.504 nm and α = β = 90° and ϒ = 120° is
Total no. of voids in 0.5 mole of a compound forming hexagonal closed packed structure are:-
Co-ordination number of sodium ion Na+ in Nacl is:-
The number of tetrahedral and octahedral voids in a CCP array of 100 atoms are respectively:
The right options for the number of tetrahedral and octahedral voids in the hexagonal primitive unit cells is ______.
Ionic radii of cation A+ and anion B- are 102 and 181 pm respectively. These ions are allowed to crystallize into an ionic solid. This crystal has cubic close packing for B-. A+ is present in all octahedral voids. The edge length of the unit cell of the crystal AB is ______ pm. (Nearest integer)
The empirical formula for a compound with a cubic close packed arrangement of anions and with cations occupying all the octahedral sites in AxB. The value of x is ______. (Integer answer)
The density of a pure substance 'X' whose atoms pack in cubic close pack arrangement is 1 g/cc. If all tetrahedral voids are occupied by 'Y' atoms. The value of '3a' is ______ g/cc, if the density of resulting solid is 'a' g/cc.
[Given: Atomic mass (X) = 30 g/mol, (Y) = 20 g/mol]
