Advertisements
Advertisements
Question
In case of hcp structure, how are spheres in first, second and third layers arranged?
Advertisements
Solution
- Hexagonal close-packed structure is obtained by stacking two dimensional hexagonal close-packed layers.
- So, the spheres in the first layer are arranged to form two dimensional hexagonal close packing.
- The spheres of the second layer are placed in the depressions of the first layer. If the first layer is labelled as ‘A’ layer, the second layer is labelled as ‘B’ layer because the two layers are aligned differently.
- The spheres of the third layer are aligned with the spheres of the first layer. The resulting pattern of the layers will be ‘ABAB....’. This arrangement results in a hexagonal close-packed (hcp) structure.
APPEARS IN
RELATED QUESTIONS
Answer the following in one or two sentences.
Mention two properties that are common to both hcp and ccp lattices.
Answer the following in brief.
Calculate the packing efficiency of metal crystal that has simple cubic structure.
Answer the following in brief.
Cesium chloride crystallizes in a cubic unit cell with Cl– ions at the corners and a Cs+ ion in the center of the cube. How many CsCl molecules are there in the unit cell?
Aluminium crystallizes 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?
In ionic crystalline solid atoms of element Y form hcp lattice. The atoms of element X occupy one-third of tetrahedral voids. What is the formula of the compound?
A compound of X and Y crystallizes in ccp structure in which the X atoms occupy the lattice points at the corners of cube and Y atoms occupy the centres of each of the cube faces. The formula of this compound is ____________.
The total volume occupied by particles m simple cubic unit cell is ____________.
The number of particles in 1 g of a metallic crystal is equal to ____________.
The vacant space in simple cubic lattice is ____________.
The coordination number of each sphere in simple cubic lattice is ____________.
Which of the following contains the highest number of atoms?
The percentage of vacant space of bcc unit cell is ____________.
Which among the following crystal structures the edge length of unit cell is equal to twice the radius of one atom?
Atoms of elements A and B crystallize in hep lattice to form a molecule. Element A occupies 2/3 of tetrahedral voids, the formula of molecule is ______.
Copper crystallises with fee unit cell. If the radius of copper atom is 127.8 pm, calculate the density of copper? (At. mass: Cu = 63.55 g mol-1)
What is the percentage of void space in bcc type of in unit cell?
An element crystallizes 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?
Silver crystallizes in face centred cubic structure, if radius of silver atom is 144.5 pm. What is the edge length of unit cell?
Gold crystallizes in face centred cubic structure. If atomic mass of gold is 197 g mol-1, the mass of unit cell of gold is ______.
AB is an ionic solid. If the ratio of ionic radius of A+ and B- is 0.52, what is the coordination number of B- ?
The relation between the radius of the sphere and the edge length in the body-centred cubic lattice is given by the formula ______.
A compound made of elements C and D crystallizes in a fee structure. Atoms of C are present at the corners of the cube. Atoms of D are at the centres of the faces of the cube. What is the formula of the compound?
The packing efficiency of bcc is ______.
Find the edge length of bcc unit cell if radius of metal atom is 126 pm.
