Explain why ionic bonds are non-directional, while covalent bonds are directional?

Hint: Directionality of the bond depends upon arrangement of the bonds inside that molecule. It can be determined by looking at the lattice structure of the compound also, but we will try to explain it theoretically here.

Complete step by step solution:
Covalent bonds are defined as the bonds formed due to sharing of electrons or we can say that they bond through overlapping of atomic orbitals of participant atoms. A covalent bond prefers specific orientations in space relative to one another which results in molecules having definite shapes. And, usually there are only few patterns of overlap and spatial arrangements possible.
For example, sigma($\sigma$) bonds can be formed by any one of the following types of combinations of atomic orbitals.
s-s overlapping: Overlap of two half-filled s-orbitals along the internuclear axis.
s-p overlapping: Overlap between half-filled s-orbitals of one atom and half-filled p-orbitals of another atom.
p–p overlapping: Overlap between half-filled p-orbitals of the two approaching atoms

Hence, they form bonds in a particular direction. Therefore, covalent bonds are directional in nature.

On the other hand, ionic bonds are different, there is no electron sharing. Ionic bonds are formed when there is a transfer of electrons from one atom to another. Since, a positive ion is attracted by a negation ion or vice versa. Due to this reason, force of attraction occurs from both of the sides. Hence, ionic bonds are non-directional in nature.

Note: We can also explain it as, in covalent bond formation, the charge distribution is axial between the reaction partners ($\sigma$ bond) or lateral between the partners ($\pi$ bond), the bonding is directional. On the contrary, the electric force fields associated with the ions are non–directional. So, it's non-directional in nature.