# What's the oxidation number of Sulfur?

The oxidation number of ANY element is $0$.
As the element, sulfur has neither been reduced nor oxidized; it still possesses 6 valence electron. Of course, in sulfates, $S {O}_{4}^{2 -}$, and sulfites, $S {O}_{3}^{2 -}$, the sulfur atom assumes formal oxidation states of $V I +$, and $I V +$; in sulfides $- I I$. What are the 2 oxidation states (or the average oxidation states if you like) of sulfur in ${S}_{2} {O}_{3}^{2 -}$, thiosulfate ion?