text: what atom has a certain element that has 11 protons and 12 neutrons? what is its isotopic notation the only identifier of an element is the number of protons.   any atom with only 1 proton is hydrogen,  8 protons is oxygen,  etc.  the element with 11 protons is sodium (na).   the different numbers of neutrons identify the isotope.  the notation is a superscript prior to the item showing the total weight.  in this case, 23na.  the link below also shows all of the known isotopes (and how they're written).