The maximum covalency for representative elements is equal to (excluding period and ion formation) :

The maximum covalency for representative elements is equal to the actual cumber of s and p-electrons in the outermost shell.

For elements without a d orbital, the maximum covalency is equal to the sum of the number of unpaired electrons in the s- and p-orbitals in the valence shell. 

The valence property known as covalency in a chemical molecule is characterized by the sharing of electrons.