The Total solution for NCERT class 6-12
Explain
(i) The basis of similarities and differences between metallicand ionic crystals.
(ii) Ionic solids are hard and brittle.
(i) The basis of similarities between metallic and ionic crystals isthat both these crystal types are held by the electrostatic force ofattraction. In metallic crystals, the electrostatic force acts between thepositive ions and the electrons. In ionic crystals, it acts between theoppositely-charged ions. Hence, both have high melting points.
The basis of differences between metallic andionic crystals is that in metallic crystals, the electrons are free to move andso, metallic crystals can conduct electricity. However, in ionic crystals, theions are not free to move. As a result, they cannot conduct electricity.However, in molten state or in aqueous solution, they do conduct electricity.