Question

What type of crystal structure is of silver metal?
(A) Fcc
(B) Simple cubic
(C) Bcc
(D) Metallic

Answer 1

Hint: The structure of metal solid is made up of metal ions arranged in a closely packed manner. The crystal structure of silver metal consists of a total four atoms in a unit cell i.e., eight eighth of atoms at corners and halves of atoms at six faces (cube has eight corners and six faces). Central atom has a coordination number of $12$.

Complete Step by step answer:
Silver metal has a crystal structure of face centered cubic (fcc) lattice with bulk coordination number $12$ where only $5{s^1}$ electron is delocalised, similar to copper and gold.
Ag electronic configuration: $[Kr]4{d^{10}}5{s^1}$

- As we know that, fcc has a packing sequence of ABCABC, such that rows of atoms in C layer are arranged in such a manner that they do not overlap atoms in either A or B layer, it is the closest possible packing of spheres leaving about only one fourth of total space available.
- Fcc has a cubic structure with an atom on each face and corner of the cube. It has coordination number $12$ (total no of nearest neighbouring central atom is having in the surrounding). Fcc is also known as cubic close packing(ccp).
- Silver is an extremely soft, ductile and malleable metal. Low hardness and high ductility of silver metal is due to the fact that unlike other metals with incomplete d-shells, it has metallic bonds with low covalent character and are relatively weak.
Therefore, we can conclude that silver metal has FCC type crystal structure.

Hence the Correct option is option A.

Note: Metals that have fcc structure are gold, copper, iridium, lead, nickel, aluminum, platinum and silver. Always remember, the noble metals (copper, silver, gold) crystallise in fcc structure at room temperature. At some specific conditions, silver can also show HCP (hexagonal close packing) structure.