Question

Explain the difference between the valence electrons and the covalency of an element.

Answer 1

Think about any element present in the periodic table. Recollect the term used for the outermost shell present in that element. In chemical bonding, we have three types of bonds namely, ionic, covalent and coordinate bonds. Think about how these bonding occurs.

Complete step by step solution:
- Valence electrons are the total number of electrons present in the outermost shell of an element.
-For example, in nitrogen, the electronic configuration is ${}^{7}N=1{{s}^{2}}2{{s}^{2}}2{{p}^{3}}$. Therefore, nitrogen has five valence electrons.
-Covalency is the number of electrons that can be shared by an element to form covalent bonds to give rise to covalent compounds. Basically, the number of shared electrons is known as covalency.
-For example, in ammonia, $N{{H}_{3}}$, nitrogen shares three electrons with three electrons of three hydrogen atoms to give rise to three covalent bonds. So, covalency of nitrogen is three.
-Valency of an element is the number of electrons that can be donated or need to be gained in order to achieve the nearest noble gas configuration. So, for nitrogen three electrons are required to attain nearest noble gas configuration. So, the valency of nitrogen is three.

Note: Generally, covalency is equal to valency for neutral molecules. Remember valence electrons are the number of electrons present in the outermost shell of an element and valency is the number of electrons required to be gained or lost to obtain noble gas configuration.