Hydrogen ion
= Hydrogen ion
{title2=$\mathrm H^+$}
{wiki}
In <acid-base chemistry>, <hydrogen ion> usually refers to positively charged hydrogen, represented by $\mathrm H^+$. In <water>, this notation describes solvated species, commonly represented by <hydronium>, rather than an isolated bare <proton>. The <hydrogen ion> <thermodynamic activity> defines <pH>.