Question

Explain : The basis of similarities and differences between metallic and ionic crystals.

Answer 1

The constituent particles of both metallic and ionic crystals are held by strong electrostatic force of attraction. In metals there is strong force of attraction between the mobile electron and positively change ions. In ionic crystals there are strong force of attraction between anion and cation. As both types of crystals have strong force of attraction so there melting and boiling points are high. Metal have free mobile electron so they conduct electricity in all there phase while ionic compound conduct electricity at molten or aqueous state only.  

(ii)

The constituent particles of ionic compound are held by strong electrostatic force of attraction. In ionic crystals there are strong force of attraction between oppositely changed anions and cations. As  the electrostatic force of attraction is very strong so that the charged ions are held in fixed positions and they cannot move easily . This is the reason of ionic crystals to be hard and brittle.

Answer 2

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★ Basis of similarities :

(i) Both ionic and metallic crystals have electrostatic forces of attraction. In ionic crystals, these are between the oppositely charged ions while in metals, these are between the valence electrons and kernels.

(ii) Both metallic and ionic compounds have high melting point.

(iii) In both cases, the bond is non-directional.

★ Basis of differences :

(i) In ionic crystals, the ions are not free to move and therefore, they do not conduct electricity in the solid state. They conduct electricity only in the molten state or in their aqueous state. However, in metals the valence electrons are free to move and hence they conducts electricity in the solid state.

(ii) Ionic bond in ionic crystals is strong due to electrostatic forces of attraction. However, metallic bond may be weak or strong depending upon the number of valence electrons and the size of the kernels.