Question

Explain

(i) Thebasis of similarities and differences between metallic and ioniccrystals.

(ii) Ionicsolids are hard and brittle.

Answer 1

1-Both ionic and metallic crystals have electrostatic forces of attraction.→→ In ionic crystals these are between oppositely charged ions.In metals these are among the valence electrons and the kernels.→→ Both have high melting point.Differences :→→ Ionic bond is strong due to electrostatic forces of attraction whereas metallic bond may be weak or strong depending upon the number of valence electrons and the size of kernels→→ In ionic bond,ions are not free to move.Hence,they cannot conduct electricity in solid state.They can do so only in molten state or in aqueous solution.
2-hey are hard because of strong electrostatic forces between atoms. They are brittle because of low mobility of defects called dislocations present in ionic solids
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