Final answer:
The ion symbol for an atom with 35 protons and 36 electrons is Cl^-1.
Step-by-step explanation:
The ion symbol for an atom with 35 protons and 36 electrons can be determined by looking at the charge of the ion. Since electrons carry a negative charge and protons carry a positive charge, the number of electrons and protons determine the overall charge of the atom. In this case, there is one more electron than proton, so the ion has a charge of -1. The symbol for this ion can be represented as Cl-1.