Answer
(a) Ionic crystals: They are composed of charged species, which are held together by electrostatic forces of attraction. Anions and cations are generally quite different in size.
Eg: $CsCl, ZnS, CaF_{2}$
(b) Covalent crystals: Atoms in covalent crystals are held together in an extensive three-dimensional network entirely of covalent bonds.
Eg: Diamond, Graphite
(c) Molecular crystals: The lattice points in molecular crystals are occupied by molecules, and the attractive forces between them are Vander waals forces and/or hydrogen bonding.
Eg: $S_{8}, I_{2}, P_{4}$
(d) Metallic crystals: Lattice points in metallic crystals are occupied by an atom of the same metal, and the bonding electrons are delocalized over the entire crystal.
Eg: Na, Mg, Fe, Cu
Work Step by Step
(a) Ionic crystals: They are composed of charged species, which are held together by electrostatic forces of attraction. Anions and cations are generally quite different in size.
Eg: $CsCl, ZnS, CaF_{2}$
(b) Covalent crystals: Atoms in covalent crystals are held together in an extensive three-dimensional network entirely of covalent bonds.
Eg: Diamond, Graphite
(c) Molecular crystals: The lattice points in molecular crystals are occupied by molecules, and the attractive forces between them are Vander waals forces and/or hydrogen bonding.
Eg: $S_{8}, I_{2}, P_{4}$
(d) Metallic crystals: Lattice points in metallic crystals are occupied by an atom of the same metal, and the bonding electrons are delocalized over the entire crystal.
Eg: Na, Mg, Fe, Cu
