Answer
Verified
402.6k+ views
Hint :We know that metals are made up of atoms. The strength of the metals depends upon the arrangement of their atoms. For the formation of the strongest metallic bonds, metals are packed as closely as possible. Several packing arrangements are possible and hcp is one of them.
Complete step by step solution:
In hcp or hexagonal closed packed arrangement of atoms, the unit cell is made up of three layers of atoms. The Top layers and the bottom layers contain six atoms at the corner of a hexagon and one atom at centre of the hexagon. The middle layer contains three atoms. The middle layer nestled between the atoms of top and bottom layers, hence it is called closed packed structure.
HEXAGONAL CLOSED PACKED STRUCTURE
Cell of hcp lattice consists of seven atoms at the top of the plane and seven atoms at the bottom plane forming a regular hexagon around a central atom. In between these planes there are three atoms which can be seen in the above diagram of hcp arrangement. There is $26\% $ void space in the unit cell of hcp and the rest of the space is efficiently occupied. HCP arrangement has coordination number $12$ and contains six atoms per unit cell.
Hence in the given problem option B is the correct answer that is $12$.
Note : The coordination number can be defined as the number of atoms touching a particular atom in a unit cell. We know that there are six corner atoms in both top and bottom layers and three atoms are within the volume of the lattice .Since each corner atom is common to all unit cells in the hcp ,the contribution of each atom is $1/6$ , the contribution of base centred atom is $1/2$ and three atoms are within the volume . So atoms per unit cell is six and coordination number is twelve.
Complete step by step solution:
In hcp or hexagonal closed packed arrangement of atoms, the unit cell is made up of three layers of atoms. The Top layers and the bottom layers contain six atoms at the corner of a hexagon and one atom at centre of the hexagon. The middle layer contains three atoms. The middle layer nestled between the atoms of top and bottom layers, hence it is called closed packed structure.
HEXAGONAL CLOSED PACKED STRUCTURE
Cell of hcp lattice consists of seven atoms at the top of the plane and seven atoms at the bottom plane forming a regular hexagon around a central atom. In between these planes there are three atoms which can be seen in the above diagram of hcp arrangement. There is $26\% $ void space in the unit cell of hcp and the rest of the space is efficiently occupied. HCP arrangement has coordination number $12$ and contains six atoms per unit cell.
Hence in the given problem option B is the correct answer that is $12$.
Note : The coordination number can be defined as the number of atoms touching a particular atom in a unit cell. We know that there are six corner atoms in both top and bottom layers and three atoms are within the volume of the lattice .Since each corner atom is common to all unit cells in the hcp ,the contribution of each atom is $1/6$ , the contribution of base centred atom is $1/2$ and three atoms are within the volume . So atoms per unit cell is six and coordination number is twelve.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Difference Between Plant Cell and Animal Cell
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
What organs are located on the left side of your body class 11 biology CBSE
Write an application to the principal requesting five class 10 english CBSE
What is the type of food and mode of feeding of the class 11 biology CBSE
Name 10 Living and Non living things class 9 biology CBSE