IONIC CRYSTAL LATTIC,oppositely, face centered cube, regular geometrical shape, electrostatic force of attraction, face centred cubic crystal , chloride, formula of sodium chloride

 IONIC CRYSTAL LATTICE:

             Arrangement of oppositely charged ions in a regular geometrical shape in which oppositely charged ions are held by electrostatic force of attraction having maximum number of contacts between oppositely charged ions and without pushing ions with same charges is called ionic crystal lattice. For example: sodium chloride has a face central cubic lattice. In this shape each face has a particle at its centre.

In the face centred cubic crystal lattice both Na⁺ and cl^- ions have six oppositely charged ions as their nearest neighbors. The structure shows 6:6 coordination and formula of sodium chloride is Nale. On the other hand cesium chloride has a body centred cube. In this arrangement each cube has a particle at the centre of the cube. Since the Cs⁺ ion is large than the Na⁺ ion, thus large number of Cl^- ions can surround Cs⁺ ion.

Each Cs+ ion has eight oppositely charged ions as nearest neighbors. The structure shows 8:8 Co-ordination, hence the empirical formula of cesium chloride is Cscl.

 FORMAITON OF IONIC BOND:

             Ionic bond is formed due to complete transference of electrons from metallic element to non-metallic element. For example. In case of sodium chloride, sodium atom loses one electron to form a uni positive ion. On the other hand chlorine atoms gains one electron to form a negatively charged ion.

             ₁₁Na = 15², 25², 2p⁶, 35¹

            Na+ = 15², 25², 2p⁶

 Similarly

            ₁₇cl = 15², 25², 2p⁶, 35², 3p⁵

            Cl- = ^152, 25², 2p⁶, 35², 3p⁶

             Na                               Na¹⁺ + e^-

            (2,3,1)                         (2,8)

 

            Cl+e^-                            Cl^θ

                                                (2,8,8)

                       As a result oppositely charged ions attract each other and arrange them self in a stable 3D crystal lattice. The ionic compounds have high melting and boiling points because in ionic crystal lattice oppositely charged ions are held by strong electrostatic attractive forces.