* Protons: The number of protons defines the element. An element with 31 protons is gallium (Ga).

* Neutrons: The number of neutrons determines the isotope. This ion has 39 neutrons, which is more than the most common isotope of gallium (which has 39 neutrons). This means it's a heavier isotope of gallium.

* Electrons: The difference between protons and electrons tells us the charge of the ion.

* 31 protons - 28 electrons = +3 charge

Therefore, the chemical symbol for this ion is Ga³⁺.