I do not understand ionic bond is non directional but covalent bond is directional ?? Please explain me easy ways. Thank you.
I will make the attempt.......
Our basic notion of ionic bonding stems from the transfer of electrons to form positive and negative ions. Each positive ion, each cation, is electrostatically bound to EVERY anion, each negative ion in the structure. Now of course, every cation electrostatically repels every other cation as well, but if you sum the attractive and repulsive forces of electrostatic interaction up across the structure (which can certainly be done quantitatively!), a net attractive force results. This is why ionic solids form crystalline, non-molecular structures.
On the other hand, our idea of covalent bonding stems from the sharing of electrons BETWEEN nuclei. The two electrons that form a bonding orbital form an electronic cloud, a region of high electron density, to which the positively charged nuclear cores are attracted, and a net attractive force results. If the nuclei get too close, internuclear repulsion occurs; if the nuclei get too far apart, they are no longer attracted to the overlapping electron cloud, The equilibrium distance, the sweet spot if you like, where interaction is maximized, is the equilibrium covalent bond length.
Unlike the ionic bond, the covalent is strongly directional, as it relies on the overlap of electron density BETWEEN nuclei, and it allows the closest internuclear approach.