Question

Define the term valency.

Answer 1

• The valency of an element is the measure of its combining capacity with other atoms in forming chemical compounds or molecules.
• It can also be defined as the number of electrons gained or lost by an atom of an element in order to achieve stability by completing its outermost shell or octet.
• For example, The compound NaCl is composed of one atom of Sodium (Na) and one atom of Chlorine (Cl). The electronic configuration of Na is 2, 8, 1. While, the electronic configuration of Cl is 2, 8, and 7. From the electronic configuration of these two atoms, it is clear that it is not easy for the Cl atom to give 7 electrons to Na. So, Cl gets one electron from Na and Na loses or gives one electron to Cl as it was the easiest way for it to achieve stability or to complete its octet. So, in this case, the valency of both Sodium and Chlorine is 1.