What is the relationship between the electronic configuration of an element and its valency?

Explanation

a. The valency of element is determined by the number of electrons present in the outermost shell of its atoms, that is, the valence electrons.
b. From the electronic configuration of an element, the number of valence electrons can be determined.
c. For elements having 1 to 4 valence electrons, valency equals the number of valence electrons.
d. For elements having 5 to 8 valence electrons, valency equals [8 - (number of valence electrons)].