Question

The thermal conductivity of silver and copper is high because they have following binding:
A.Metallic
B.Ionic
C.Covalent
D.Vander waal

Answer 1

Hint: Thermal conduction is mainly due to migration of free electrons when temperature is raised. Since copper and silver are transition metals; and metals have a large number of free electrons, they are good conductors of heat and electricity.

Complete step by step answer:
-Metals are good conductors of heat and electricity. They have high electrical conductivity, high thermal conductivity and high density. They have some characteristic properties such as malleability and ductility, tendency to deform under stress without cleaving into sheets and wires. They are shiny and lustrous in terms of optical properties. Metallic sheets are few micrometres in thickness and appear opaque.
-Metals have higher densities than most non-metals but still we notice wide variations in their densities. Such as lithium is the least dense solid element and osmium being the densest. We also know that alkali and alkaline earth metals are light metals due to their low density, hardness and melting point.
-Metals have metallic bonding in them. So, the strength of metallic bonds for different metals reaches a maximum around the centre of the transition metals series because they have a large number of delocalized electrons in a tight binding type of metallic bonds. Therefore, silver and copper have high thermal conductivity as they lie in transition metal series and exhibit metallic properties.
-Thermal conductivity is the ability of the material to transport heat from one point to another without movement of the whole material.Metals have a large number of free electrons and due to their electronic conduction, heat can be conducted as well. The free electrons move freely throughout the solid and transfer the thermal energy because they possess metallic bonding.
-Especially for transition metals, they can involve the 3d as well as 4s electrons in delocalisation. The more electrons you involve, the stronger the attractions will be and so is the metallic bonding. This causes the effective nuclear charge on the cation to increase and thus decrease the size of cation. That is why, we say that the thermal conductivity of silver and copper is high because they have metallic bonding.

Hence, the correct option is (A).

Note:
The strength of metallic bonds depends upon the number of delocalized electrons, charge on metal cation and size of the cation as well. Metallic bonds are strong and require large amounts of energy to break them. This reason remains the same for the fact that metals have high melting and boiling points.