What is the Difference Between Valency and Oxidation State?

Valency and oxidation state are two different concepts related to the interactions of atoms in chemical compounds. The main differences between them are:

1. Definition: Valency refers to the number of electrons an atom can lose, gain, or share to become stable, while oxidation state refers to the number of electrons an atom has gained or lost in a particular compound.
2. Nature: Valency is the maximum number of electrons an atom can lose, gain, or share, and it has no sign. In contrast, the oxidation number is the hypothetical charge of an atom in a molecule or ion, and it is a measure of its apparent capacity to gain or lose electrons within that species.
3. Application: Valency is applicable to any chemical element, while the term oxidation number is mainly applied regarding coordination complexes.
4. Determination: Valency is determined by the number of valence electrons in a neutral atom, while oxidation number is determined by the oxidation state due to electronegativity.

For example, nitrogen has a valency of 3, as it has three valence electrons in its outermost shell. However, it can have oxidation numbers ranging from -3 to +5, depending on the compound it forms. In a compound like NH3, nitrogen has a valency of 3, but its oxidation number is -3.

Comparative Table: Valency vs Oxidation State

The main difference between valency and oxidation state lies in their definition and application. Here is a table highlighting the key differences between the two concepts:

Valency describes an atom's combining capacity and is related to the number of electrons in its outermost shell. On the other hand, oxidation state is a measure of an atom's apparent capacity to gain or lose electrons within a molecule or ion, and it can have both positive and negative signs.