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
The coordination number of atoms in bcc crystal lattice is ______.
Choose the most correct answer.
A compound forms hcp structure. Number of octahedral and tetrahedral voids in 0.5 mole of substance is respectively _______.
Answer the following in one or two sentences.
Sketch a tetrahedral void.
Answer the following in brief.
How are the spheres arranged in first layer of simple cubic close-packed structures? How are the successive layers of spheres placed above this layer?
How are tetrahedral and octahedral voids formed?
The number of octahedral voids formed in 0.5 mol of a compound forming hcp structure?
In hexagonal close packed (hep) structure, ____________ layer and ____________ layer have horizontal and vertical alignment.
A metal crystallizes in bcc lattice with edge length 4.48 Å. The radius of the metal atom is ___________ Å.
An element crystallises in a bee lattice with cell edge of 500 pm. The density of the element is 7.5 g cm-3. How many atoms are present in 300 g of metal?
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)
The coordination number of each sphere in bcc lattice is ____________.
In two dimensional AAAA type packing, the coordination number of each sphere is ____________.
The coordination number of Rh in the complex [Rh(NH3)3(SCN)3] is ____________.
Which of the following is CORRECT for the two dimensional arrangement of spheres given below?
The atoms of element 'Y' form hexagonal close packing and the atoms of element X occupies `3/4` th portion of the number of tetrahedral voids. The formula of the compound formed by X and Y is ____________.
What is the coordination number of cation in ionic compound if the type of hole occupied by cation is octahedral?
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 among the following metals crystallise as a simple cube?
What is the coordination number of atoms in bcc crystal lattice?
Predict the type of cubic lattice of a solid element having edge length of 400 pm and density is 6.25 g/ml.
(Atomic mass of element = 60)
Calculate the total number of tetrahedral and octahedral voids formed in 0.6 mol of a compound if it forms hcp structure.
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.
