To avoid the implication of the naked "solvated proton" in solution, acidic aqueous solutions are sometimes considered to contain a less unlikely fictitious species, termed the "hydronium ion" (H3O+). However, even in this case, such solvated hydrogen cations are more realistically conceived as being organized into clusters that form species closer to H9O+4. Other oxonium ions are found when water is in acidic solution with other solvents.
Using the atomic number of an element, you can determine the number of what found in the nucleus?
proton