Explain : (a)The basis of similarities and differences between metallic and ionic crystals. (b)Ionic crystals are hard and brittle.

Explain : (a)The basis of similarities and differences between metalli

1.	Explain : (a)The basis of similarities and differences between metallic and ionic crystals. (b)Ionic crystals are hard and brittle.
Answer» Solution :(a) Similarities . (i) Both ionic and metallic crystals have electrostatic forces forces of attraction. In ionic crystalstheseare between the oppositely charged ions. In metals, these are among the VALENCE electrons and the kernels. That is why both have high melting point. (ii) In both CASES, the bond is non-directional. Difference . (i) In ionic crystals , the ions are not free to move. HENCE,they cannot conduct electricity TEH soild state.They can do so only in the molten state or in aqueous solution. In metals, the valence electrons are free to flow. Hence, they can conduct electricity in the solidstate. (ii)Ionic bond is strong due to electrostatic forces of attraction. Metallic bond may be weak or strongdepending upon the number of valence electrons and the size of the kernels. (b)Ionic crystals arte hard becausethere are strongelectrostatic forces of attraction among the oppositelycharged ions. they are brittle because ionic bond is non-directional.