The oxidation number of boron (B) can vary depending on its chemical environment. In most of its compounds, boron typically exhibits an oxidation state of +3.
Boron has three valence electrons, which it can lose to form stable compounds. For instance, in boron trifluoride (BF3), boron donates its three electrons to form bonds with three fluorine atoms, thus exhibiting a +3 oxidation state.
However, in some cases, boron can have oxidation states of -3, such as in boron hydride (BH3), where it shares its electrons with hydrogen atoms in a way that indicates a lower oxidation state.
In summary, while the most common oxidation state of boron is +3, it can also be found in lower or higher states depending on the specific compounds and reactions involved.