Why is the +5 oxidation state of bismuth rare and unstable?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A labeled periodic table element box for bismuth shows atomic number 83, symbol Bi, atomic weight 208.9804, electron configuration, and properties including solid state, rhombohedral crystal structure, and weakly acidic oxides. — bismuth Properties of bismuth.

The +5 oxidation state of bismuth is considered rare and unstable primarily because of the element's electronegativity and the behavior of its valence electrons.

Bismuth has a somewhat lower electronegativity compared to other elements in the nitrogen group. Furthermore, its lone pair of electrons is evidently quite inert, which hinders the element's ability to achieve and maintain the +5 oxidation state.1