Explain
(i) The basis of similarities and differences between metallic and ionic crystals.
(ii) Ionic solids are hard and brittle.
Explain
(i) The basis of similarities and differences between metallic and ionic crystals.
(ii) Ionic solids are hard and brittle.
Similarities
(a) Ionic and metallic crystals both have electrostatic force of attraction. In ionic crystals, this force is between oppositely charged ions whereas, in metals, this force is in between the valence electrons and the kernels.
(b) In both cases, the bond is non - directional
Differences
(a) In ionic crystals, ions are not free to move. So, they don't conduct electricity in solid-state. They are conductors only in molten state or aqueous solution. In metals, valence electrons can move. Hence, they can conduct electricity in solid-state.
(b) Ionic bonds are strong whereas metallic bonds may be weak or strong.
(ii) Ionic crystals are hard because there are strong electrostatic forces of attraction among the oppositely charged ions. They are brittle because the ionic bond is non-directional.
Similarities
(a) Ionic and metallic crystals both have electrostatic force of attraction. In ionic crystals, this force is between oppositely charged ions whereas, in metals, this force is in between the valence electrons and the kernels.
(b) In both cases, the bond is non - directional
Differences
(a) In ionic crystals, ions are not free to move. So, they don't conduct electricity in solid-state. They are conductors only in molten state or aqueous solution. In metals, valence electrons can move. Hence, they can conduct electricity in solid-state.
(b) Ionic bonds are strong whereas metallic bonds may be weak or strong.
(ii) Ionic crystals are hard because there are strong electrostatic forces of attraction among the oppositely charged ions. They are brittle because the ionic bond is non-directional.
