<Li> Zundel cation: H O (named for Georg Zundel) </Li> <Li> Eigen cation: H O (or H O 3H O) (named for Manfred Eigen) </Li> <P> Zundel cations and Eigen cations play an important role in proton diffusion according to the Grotthuss mechanism . </P> <P> In connection with acids, "hydrogen ions" typically refers to hydrons . </P>

Why can hydrogen form both positive and negative ions