It is said that covalent bonds are directional, while ionic bonds are not. Why? Is it because of the orientation/directional properties of the overlapping orbitals?
The meaning of covalent bonds being directional is that atoms bonded covalently prefer specific orientations in space relative to one another. As a result, molecules in which atoms are bonded covalently have definite shapes.
The reason for this directionality is that covalent bonds are formed by sharing electrons between atoms, or, in other words, as you said, by overlapping the atomic orbitals of participant atoms. And usually only few patterns of overlap are possible, consequently, only few spatial arrangements of atoms are possible.
Ionic bonds are different: there is no electron sharing (or atomic orbital overlaps) and the number of anions surrounding a cation is limited by the charges of the ions, their sizes, and the efficiency of the lattice packing.
Very well put. Another explanation is that as covalent bonds are made by 'sharing' of electron, the electron will 'spend' more time with the element which is more electronegative. e.g in HCl, H has the electronegativity of 2.1 while Cl has 3, so the 'pull' of Cl on the shared electron is greater than H, hence the direction. Hence covalent bonds show directionality because of the shape of their electron wavefunction. Its the probability of finding an electron in a certain direction which is in turn effected by the partial charges. Even Ionic bonds show directionality (because there is no 'true' ionic' bond) but its very slight.
In covalent bond mutually sharing present between more or less electronegative element. Eg; if we consider two elements A and B.electronegative of A is more than B.then electron density more on A and less on B. As a result B easily lose electron means that their is direction of losing electron and it's direction depends upon electronegative of element hence covalent bond is directional bond