Advertisements
Advertisements
Question
Third layer of spheres is added to second layer so as to form hcp or ccp structure. What is the difference between the addition of third layer to form these hexagonal close-packed structures?
Advertisements
Solution
- The first one-dimensional row of a hexagonal closed-packed (hcp) structure has depressions between neighbouring atoms.
- When a second row is organised so that spheres fit in the depressions, a staggered pattern results. If row 1 is A, row 2 is B.
- When the third row is staggered and in contact with the second row, an A-type layout is created.
- Similarly, the spheres in the fourth row can be organised as a B-layer. This results in the layers being given to the ABAB type. This produces a hexagonal close packing (hcp) structure.
APPEARS IN
RELATED QUESTIONS
Choose the most correct answer.
In crystal lattice formed by bcc unit cell, the void volume is _______.
The coordination number of atoms in bcc crystal lattice is ______.
Answer the following in one or two sentences.
Sketch a tetrahedral void.
An octahedral void is surrounded by ________.
The number of tetrahedral voids are formed if the number of atoms in a crystal is N/2.
A metal crystallizes in bcc lattice with edge length 4.48 Å. The radius of the metal atom is ___________ Å.
A metallic element crystallises in simple cubic lattice. If edge length of the unit cell is 3Å, with density 8 g/cc, what is the number of unit cells in 100 g of the metal?
(Molar mass of metal = 108 g/mol)
A compound has fcc structure. If density of unit cell is 3.4 g cm−3, what is the edge length of unit cell?
(Molar mass = 98.99)
In ABCABC type arrangement of spheres, the coordination number of any sphere is __________.
Which of the following has hcp crystal structure?
What is the coordination number of cation in ionic compound if the type of hole occupied by cation is cubic?
A metallic element crystallizes in simple cubic lattice. If edge length of the unit cell is 3Å, with density 8 g/cc, what is the number of unit cells in 108 g of the metal?
(Molar mass of metal = 100 g/mol)
Aluminium crystallises in a cubic close-packed structure with a unit cell edge length of 353.6 pm. What is the radius of Al atom? How many unit cells are there in 1.00 cm3 of Al?
Percentages of free space in cubic close-packed structure and in the body-centered packed structure are respectively ______.
Which metal crystallises in a simple cubic structure?
Which among the following metals crystallise as a simple cube?
What is the coordination number of atoms in bcc crystal lattice?
The number of octahedral sites per sphere in ccp structure is ______.
How much vacant space is present in hep crystal lattice?
Find the total number of tetrahedral and octahedral voids formed in 1 mole of a compound forming hcp structure.
If the length of the body diagonal of a FCC unit cell is xÅ, the distance between two octahedral voids in the cell in Å is ______.
Calculate the volume occupied by a particle in a simple cubic unit cell if the volume of the unit cell is 5.5 × 10−22 cm3.
What is the minimum number of spheres required to develop an octahedral void?
